CONCEPT September 2006

Transcription

1 CONCEPT September 2006 Development and application of the integrated model MITERRA-EUROPE

2 Commissioned by.., (eventueel) programme number and programme name. 2 Alterra-Concept 15 november task 1.doc

3 CONCEPT September 2006 Development and application of the integrated model MITERRA-EUROPE Contents of the report of task 1 of the service contract integrated measures in agriculture to reduce ammonia emissions Velthof, G.L. (ed.) Alterra-Concept 15 november task 1.doc Alterra, Wageningen, 2006

4 ABSTRACT Author(s), Title; subtitle. Wageningen, Alterra, Alterra-Concept 15 november task 1.doc. 164 blz.;... figs.;.. tables.;.. refs. Keywords: ISSN Alterra P.O. Box 47; 6700 AA Wageningen; The Netherlands Phone: ; fax: ; info.alterra@wur.nl No part of this publication may be reproduced or published in any form or by any means, or stored in a database or retrieval system without the written permission of Alterra. Alterra assumes no liability for any losses resulting from the use of the research results or recommendations in this report. 4 Alterra-Concept 15 november task 1.doc [Alterra-Concept 15 november task 1.doc/maand/2006]

5 CONCEPT September 2006 Contents Abstract... 7 Extended summary Introduction 9 2 Description of MITERRA EUROPE Method of calculation and input data Introduction Emissions of ammonia, nitrous oxide, and methane s NOX emissions Changes in soil organic nitrogen Nitrate leaching Phosphorus balance Measures Ammonia emission Nitrogen leaching Introduction Measures to decrease nitrate leaching in NVZ Qualitative estimation of the costs Phosphorus leaching Temporal and spatial scales Scenarios Reference year Measures taken after full implementation of the Nitrate Directive Measures taken after implementation of the Water Framework Directive (WFD) Description of the three RAINS scenarios 34 3 Results and Discussion Reference year Maps Effects of ammonia measures on emissions of ammonia, nitrate, nitrous oxide, methane and NOX Maps Effect of measures in comparison to Effect of nitrate measures on emissions of ammonia, nitrate, nitrous oxide, methane and NOX Maps Effect of measures in comparison to Results of scenarios Year Full implementation of Nitrate Directive 53

6 3.4.3 Water Framework Directive RAINS Baseline scenario RAINS National scenario RAINS NEC scenario Discussion 53 References...54 Annex 1. Nitrate measures affecting ammonia emission (input for RAINS scenarios)...55 Annex 2. Detailed information on input data...63 Annex 3. Calculation of leaching in MITERRA-EUROPE...64 Annex 4. Desk study of surface runoff from application of fertilisers and organic manure to soils...85 Annex 5. Desk study on bufferstrips Annex 6.Technical description of MITERRA-EUROPE Annex 7. Detailed results Annex 8. Summary for each country of measures, emission factors, and possible differences with CAPRI and/or RAINS/GAINS Annex 9. Measures in the Nitrate Directive Annex 10. Implementation of measures of the action programmes of the Nitrate Directvie and the Codes of Good Agricultural Practice in the different member states Alterra-Concept 15 november task 1.doc

7 CONCEPT September 2006 Abstract Extended summary Alterra-Concept 15 november task 1.doc 7

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9 CONCEPT September Introduction European Commission, Directorate-General Environment has contracted Alterra, Wageningen UR for the Service contract: integrated measures in agriculture to reduce ammonia emissions. The general objective of the service contract is to have defined the most appropriate integrated and consistent actions to reduce various environmental impacts (notably water, air, climate change) from agriculture. Specifically, the objective is to have developed and applied a methodology allowing to assess and quantify the costs and the effects of various policies and measures aiming at reducing the impact of agriculture on water air pollution and climate change. Both ancillary benefits and trade offs of measures have to be identified. The impacts and feasibility of the most promising measures have to be analysed in depth. The service contract describes the following five tasks: 1. Develop an integrated approach. 2. Analysis of International and European instruments 3. In depth assessment of the most promising measures 4. Impact assessment of a possible modification of the IPCC directive 5. Stakeholder consultation, presentations, workshops. In this report, the integrated approach of task 1 is described. A model (MITERRA- EUROPE) is developed in order to: i) assess the effects of the implementation of the ammonia abatement techniques on emissions of NO 3, NH 3, N 2 O, and CH 4, and on the phosphorus balance; ii) assess the effects of the implementation of measures to decrease nitrate leaching on emissions of NO 3, NH 3, N 2 O, and CH 4, and on the phosphorus balance. MITERRA-EUROPE is a simple model consisting of input module with activity data and emission factors, a set of (packages of) measures to mitigate NH 3 emission and NO 3 leaching, a calculation module, and an output module (presenting results in tables). The data-base of MITERRA-EUROPE is on NUTS 2 level and includes data of N inputs, N outputs, N surplus, land use, soil type, topography, livestock numbers etc., and emission factors for NH 3, N 2 O, NO X and CH 4, and N leaching factors. In MITERRA-EUROPE, also emissions of NO X from agricultural sources (housing and soils) are included. Phosphorus is an important nutrient causing eutrophication of surface waters and, thus, is important for both the Nitrate Directive and the Water Framework Directive. Therefore, in MITERRA-EUROPE also a phosphorus balance on NUTS- 2 level is included, by which it is possible to calculate the effects of measures on phosphorus surplus in agriculture. Alterra-Concept 15 november task 1.doc 9

10 Effects of NH 3 and NO 3 measures on the emissions of the greenhouse gases N 2 O and CH 4 are included. This facilitates the identification of integrated measures to reduce emissions of NH 3, NOx, and greenhouse gases to the atmosphere and the leaching of nitrogen and phosphorus to ground and surface waters. The effectiveness of abatement options for NH 3 emission and implementation of the measures and Codes of Good Agricultural Practice and Action Programs of the Nitrate Directive can be calculated on a regional scale (NUTS 2 level). In Chapter 2 descriptions are given of the ammonia measures and nitrate measures that are included in MITERRA-EUROPE. The starting point for MITERRA-EUROPE are the existing models CAPRI, MITERRA and INITIATOR, supplemented with existing data bases, soil data and expertise about emission processes, with the RAINS/GAINS model as reference. This MITERRA-Europe is a simple model programmed in the language GAMS. The advantage of using GAMS is that the model can be directly coupled to the data base of CAPRI (which is modelled in GAMS) and the equations for calculating nitrate leaching can be easily transferred to CAPRI and used for the in-depth assessments in task 3. In chapter 2 a description of MITERRA-EUROPE is given, in chapter 3 the results for the year 2000 and after implementation of measures are presented and discussed (including three scenarios of implementation of the Nitrate Directive and three RAINS scenarios). In chapter 4 the major conclusions are presented. In the Annexes detailed description of the model, the results of desk studies and detailed results of the calculations are presented. 10 Alterra-Concept 15 november task 1.doc

11 CONCEPT September Description of MITERRA EUROPE 2.1 Activity data A detailed descriptions of the model and activity data are found in Annex 6. In Miterra-Europe the animal categories from RAINS are used and the number of animals are derived from CAPRI. RAINS calculates on NUTS0-level and the number of animals of CAPRI are given on NUTS2-level. The animals from CAPRI are aggregated to animal categories used in RAINS. Data on housing systems and grazing period are derived from RAINS (on NUTS0- level). The nitrogen excretion per animal head is derived from RAINS. The application rates of manure are recalculated from CAPRI (the excretion of RAINS is used and the distribution of the manure of the crops is based on CAPRI). Both the area of the different crops and the crop specific mineral fertilizer application rates in 2000 are derived from CAPRI. The amount of crop residues are calculated using TIER-1 method of the IPCC. The estimation of N fixation is based on the TIER-1 method of the IPCC of The nitrogen fixing crops are pulses and soya are the same as those from CAPRI. The area of histosols is used for calculation of the N 2 O emission using IPCCmethodology. All data on soil types and properties and meteorology are derived from CAPRI- DYNASPAT. 2.2 Method of calculation and input data Introduction In figure. a schematic presentation of MITERRA-EUROPE is given. The following calculations are carried out (on different scales (see paragraph 2.3): o Total excretion = number of animal x excretion per animal, for the different types of animals o Part of the N is excreted during grazing and part of the N is excreted in housing and stored in manure storage o Gaseous N losses (NH3, N2, N2, NOX) from housing and storage are calculated using emission factors o Leaching from manure storage is calculated with leaching fractions Alterra-Concept 15 november task 1.doc 11

12 o Some manure may be treated of exported (and not used in agriculture) o Gaseous N losses (NH3, N2, N2, NOX) from the different N sources of soils (manure, grazing, fertilizer, atmospheric deposition, biological N fixation are calculated using emission factors) o Surface runoff from the different N sources of soils is calculated with surface runoff fractions o The nett N mineralization of soil organic matter is calculated, i.e. mineralization minus accumulation. o The N removal via crop yield is calculated. o The N surplus of the soil is calculated from the total N input, the N removal via crops, and gaseous N losses an d surface runoff from the different N sources of soils (manure, grazing, fertilizer, atmospheric deposition, biological N fixation). o The N surplus is divided in leaching below the rooting zone and denitrification using leaching fractions (leaching fraction = 1 denitrification fraction). The required activity data are derived from the database of CAPRI at NUTS-2 level. Data are available of farm statistics, N inputs and outputs, number of livestock and farm buildings. In MITERRA-EUROPE the 25 member countries of the EU are included, plus Bulgaria, Romania, and Croatia. Turkey is not included, because the required activity data and emission factors are not available yet. 12 Alterra-Concept 15 november task 1.doc

13 CONCEPT September 2006 Figure. Schematic presentation of MITERRA-EUROPE. In grey the used sources of information are presented. Service contract means that the data/calculation is obtained in the current project. In Annexes 3 and 4 detailed descriptions of MITERRA-EUROPE is presented Emissions of ammonia, nitrous oxide, and methane The emission factors for NH 3, N 2 O and CH 4 are derived from the RAINS/GAINS model, so as to maintain consistency in the environmental assessments. These national emission factors are used on NUTS-2 level. No specific NUTS-2 emission factors are derived for NH 3, N 2 O and CH 4, unless available information and data will allow us to do so NOX emissions NOX emissions are calculated using emission factors of RAINS/GAINS. For emission factors that are not included in RAINS/GAINS, it assumed the NOX emission factor is equal to that of N2O. NOx and N2O are produced during the same processes (nitrification and denitrification) and studies indicate that emission factors for N2O and NOX are mostly similar. Alterra-Concept 15 november task 1.doc 13

14 2.2.4 Changes in soil organic nitrogen Changes in soil organic nitrogen contents of the soil also affect the nitrogen surplus. In MITERRA-EUROPE changes in organic nitrogen contents of the soil are based on soil properties and nitrogen inputs. One of the measures within the Nitrate Directive demands for balanced nitrogen fertilizer application, in which the nitrogen demand of a crop is tuned to the amount of plant-available nitrogen. This includes the input of nitrogen via fertilizer and manure, but also the nitrogen mineralized from soil organic matter. The results of the calculated mineralization in MITERRA- EUROPE are also used for assessing the effect of implementation of the measure of balanced fertilization. In Annex 3 a description is give of the MITERRA-methodology to calculate the leaching of nitrate from agricultural sources, which also includes the methodology of calculating mineralization and accumulation of N. Briefly, mineralization and accumulaton are calculated using data on temperature, land-use, organic C content, nitrogen surplus Nitrate leaching The Nitrate Directive aims at decreasing the nitrate leaching from agricultural sources to ground and surface waters. This includes the leaching of nitrate from fertilizer and manure applied to land. Special attention in the Codes of Good Agricultural Practice of the Nitrate Directive is paid to prevent/decrease the nitrogen leaching from stored manure and manure and fertilizers applied to sloping soils. Therefore, a module is included in MITERRA-EUROPE to estimate leaching from stored manure and from sloping soils (via runoff). The following leaching pathways in soils are considered in MITERRA-EUROPE: Runoff Leaching below rooting depth, dived into o Leaching to larger surface water via subsurface flow o Leaching to groundwater + small surface waters In Annex 3 a description is give of the MITERRA-methodology to calculate the leaching of nitrate from agricultural sources, i.e. i) leaching below rooting zone, ii) leaching from surface-runoff, and iii) leaching from stored manure. This Annex also contains the results of the desk studies on leaching. Below a brief description of the three leaching pathways is given. i) N leaching and surface run-off from stored manure. Manure that is stored in the open air without a concrete floor is susceptible to leaching and runoff to groundwater and surface water. In the Nitrate Directive, special attention is paid to decrease the risk on N leaching from stored manure. In MITERRA-EUROPE a method is included that estimates leaching from stored manure, using data on manure storage type in the different countries. Table shows the.estimates of the leaching fractions for stored manures are 14 Alterra-Concept 15 november task 1.doc

15 CONCEPT September 2006 Table 3. Leaching fractions for stored manure. Type of manure system Concrete floor Cover Leaching fraction, % of stored N Liquid/slurry no no 10 yes 5 yes no 0 yes 0 Solid no no 5 yes 2 yes no 2 yes 0 ii) surface runoff The risk on surface runoff of applied fertilizer and manure is especially high for sloping soils, although some runoff may also occur during wet conditions in flat areas. Surface runoff is calculated on basis of slope, rainfall and crop parameters. The fate of the N that has been leached via runoff is not included in MITERRA- EUROPE. In the figure, the leaching fraction is presented for EU-15 (note that data for the other countries are not yet available. The required soil and environmental data are derived from the CAPRI-Dynaspat project. Alterra-Concept 15 november task 1.doc 15

16 Percentage of applied N Figure. Surface runoff fractions in EU-15s, % of the N applied via fertilizer and manure. iii) leaching below the rooting zone. The leaching of nitrogen below the rooting zone is calculated using data of the soil nitrogen surplus and some location specific factors (including soil type, organic matter content, weather conditions). Part of the nitrogen will leach to deeper groundwater, part to surface water, and part is denitrified. The leaching below rooting depth is dived as follows in leaching to larger surface waters and leaching to groundwater + small surface waters. It is assumed that the total leaching to the large surface waters via surface flow is equal to the leaching below surface water of an area of 500 meter width near the large surface waters in agricultural regions. Firstly, the length of borders of large surface waters in agricultural regions on NUTS II level is calculated and secondly, the total length of the border is multiplied with 500 m to obtain the area of leaching to larger surface waters. The percentage of the is area of the total area of agricultural soils on NUTS II level In the figure, the leaching fraction is presented for EU-15 (note that data for the other countries are not yet available. The required soil and environmental data are derived from the CAPRI-Dynaspat project). 16 Alterra-Concept 15 november task 1.doc

17 CONCEPT September 2006 Figure. Leaching fractions in EU-15s, % of the N applied via fertilizer and manure Phosphorus balance The phosphorus (P) surplus is calculated as follows: P surplus = P input manure + P input grazing + P input fertilizer P removal via crop, all in kg P2O5 per ha per year All input data are derived from CAPRI. 2.3 Measures Ammonia emission For each of the major sources of ammonia emissions (livestock farming, fertilizer use, and chemical industry), RAINS considers a number of emission control options. Ammonia emissions from livestock manures occur at four stages, i.e., (i) in the stable, (ii) during storage of manure, (iii) following its application and (iv) during the grazing period. At each stage, emissions can be controlled by applying various techniques. The major abatement categories for agriculture considered in RAINS are Alterra-Concept 15 november task 1.doc 17

18 Low Nitrogen Fodder (dietary changes), e.g., multi-phase feeding for pigs and poultry, use of synthetic amino acids (pigs and poultry), and the replacement of grass and grass silage by maize for dairy cattle; Stable Adaption by improved design and construction of the floor (applicable for cattle, pigs and poultry), flushing the floor, climate control (for pigs and poultry), or wet and dry manure systems for poultry; Covered Manure Storage (low efficiency options with floating foils or polystyrene, and high efficiency options using tension caps, concrete, corrugated iron or polyester); Biofiltration (air purification), i.e., by treatment of ventilated air, applicable mostly for pigs and poultry, using biological scrubbers to convert the ammonia into nitrate or biological beds where ammonia is absorbed by organic matter; Low Ammonia Application of Manure, distinguishing high efficiency (immediate incorporation, deep and shallow injection of manure) and medium to low efficiency techniques, including slit injection, trailing shoe, slurry dilution, band spreading, sprinkling (spray boom system). urea substitution, substitution of urea with ammonium nitrate incineration of poultry manure In MITERRA-EUROPE, the ammonia measures (and parameters) of RAINS (as listed above) are included. The removal efficiencies for ammonia from RAINS on a country level (tables 5.1 in Klimont & Brink, 2004) are used on NUTS II level. No refinement of the removal efficiencies on NUTS 2 level made. This means that it is assumed that the effect of measures, expressed as removal efficiency, is the same in all NUTS 2 regions within a country. If there is a difference in removal efficiency between regions in a country, the amount of manure nitrogen that is applied to the soil also differs (more ammonia emission, less applied nitrogen). This may also affect the calculated leaching. However, deviations of the real removal efficiency compared to the national removal efficiency will only have minor effects on leaching. The removal efficiencies for N2O and CH4 are presented in table xxxx (table 5.3 in Klimont & Brink, 2004). The measures identified in the UNECE Expert Group on NH3 abatement are divided in the four major agricultural NH3 sources housing, grazing, manure storage, land spreading of manures. The measures are the same as those in RAINS/GAINS, but also include specifications and modifications. In MITERRA-EUROPE, the ammonia measures (and parameters) of RAINS/GAINS (as listed above) 18 Alterra-Concept 15 november task 1.doc

19 CONCEPT September 2006 Table. The removal efficiencies for ammonia from RAINS on a country level (table 5.1 in Klimont & Brink, 2004) Alterra-Concept 15 november task 1.doc 19

20 2.3.2 Nitrogen leaching Introduction Within the Nitrate Directive two types of strategies to decrease nitrate pollution can be disntinguished: i) code or codes of good agricultural practice for the whole country with the aim of providing for all waters a general level of protection against pollution. These codes of good agricultural practice have to be implemented by farmers on a voluntary basis (including provision of training and information for farmers). See Annex 9 or description of Codes of Good Agricultural Practice. ii) action programmes in respect of designated vulnerable zones, including the measures of Annex III of the directive (see Annex 9 of this report) and the measures for the Codes of Good Agricultural Practice (see Annex 9). For most measures only outlines are given (see Annex 9) and the countries can fulfill these measures in different ways. In MITERRA-EUROPE a list of measures to decrease nitrate leaching is set up. It is assumed that packages of measures are implemented to decrease nitrate leaching and to fulfill to the constraints of the Nitrate Directive. The degree of implementation of the different measures will vary between countries and the NUTS II regions. For all countries, the degree of implementation of the measures which are assumed to be necessary for full implementation of the Nitrate Directive in Nitrate Vulnerable Zone (NVZ). This is estimation of implementation of measures is based on the evaluation of the action programmes for the Nitrate Directive (period ; 20 Alterra-Concept 15 november task 1.doc

21 CONCEPT September 2006 Alterra from service contract 2005/409860/MAR/B1) and assumptions for full implementation of the Nitrate Directive. The following measures to decrease nitrate leaching in NVZ are included in MITERRA-EUROPE; 1. balanced N fertilizer application based on soil analysis, expected N mineralisation, weather conditions, and crop demand 2. maximum manure N application standard of 170 kg N per ha (except where a derogation applies). In certain areas the number of animals must be decreased. 3. no fertilizer and manure application in winter and wet periods 4. limitation to fertilizer application on steeply sloping grounds 5. manure storage with minimum risk on runoff and seepage 6. appropiate fertilizer and manure application techniques, including split application of nitrogen 7. preventation of leaching to water courses, e.g. via bufferstrips 8. growing winter crops For implementation of the Water Framework Directive (WFD) it is assumed that the above mentioned measured for the NVZ are implemented for the whole area. Moreover, in MITERRA-EUROPE two measures to decrease the risk on phosphorus leaching to surface water are included. These type of measures are required for the Water Framework Directive: 9. Equilibrium of P fertilization (P input = P output) 10. Mining of P (P input < P output) In MITERRA-EUROPE, the effect of single measures can be calculated and the effect of packages of measures. For full implementation of Nitrate Directive and WFD packages of measures are selected. However, it must be noted that it is not possible to include all specific and detailed measures from the action programmes (in total there are more that 50 action programmes) of the countries for the Nitrate Directive. Therefore, a more general approach is chosen, based on implementation of the above-mentioned measures in NVZ or countries. For this, the results of the Nitrate Action programmes of the different member states are used (Annex 10) The extent of implementation of part of the measures depends on specific data of countries and NUTS II regions (such as nitrogen and phosphorus surplus, presence of open manure storages etc.) Measures to decrease nitrate leaching in NVZ Balanced N fertilizer application The amount of N fertilizer applied and manure applied is tuned to the crop N demand, accounting for atmospheric deposition, mineralization, and biological N fixation. The following calculations are made: Alterra-Concept 15 november task 1.doc 21

22 I. The N demand of the crop is calculated: IA. It is assumed that the crop yield (and N removed via harvested product) in 2000 is optimal for the certain region. Thus, with balanced N fertilizer application, the yield of 2000 must be achieved. The data of yields in 2000 are derived from CAPRI and are based on Eurostat. IB. The N uptake in the non-harvested crop parts (roots and crop residues) is estimated for each crop (using crop types of CAPRI). The data are derived from CAPRI or from the ratio between harvested product and non-harvested parts. IC. From IA and IB the total N uptake by crops in each NUTS II region and NVZ is calculated. ID. To achieve the optimal yield, more N must be present in the soil than the total amount of N taken up by the plants. Part of this extra N is derived from mineralization of soil organic matter and part must be applied via manure and fertilizer It is assumed that this over-fertilization (F of ) amounts depends on the crop: 5% of the the total N uptake of the crop for grassland and cereals 25% of the total N uptake of the crop for vegetables, fruits and other perennials 15% of the total N for all other crops Thus, the total N demand of the crop = F of * [(N in harvested products) + (N in non-harvested crop parts)] II. The total amount of plant-available N is calculated IIA. Sources of plant-available N are: Manure (= excretion in stable gaseous losses in stable). Excretion during grazing (= excretion during grazing). Fertilizer (= fertilizer applied). Biological N fixation Atmospheric N deposition Nett N mineralization The N of these sources is not always available for plant uptake (part is rapidly lost as ammonia and part is present as organic N, which become slowly available by mineralization and part leaches via surface runofff). To estimate the amount of plantavailable N a fertilizer N equivalency is introduced. The fertilizer equivalency of fertilizer containing only nitrate and that is applied under conditions without surface runoff is by definition set at 100%. The most common fertilizers containing both nitrate and ammonium and have a somewhat less fertilizer equivalency, because some ammonia volatilization occurs 22 Alterra-Concept 15 november task 1.doc

23 CONCEPT September 2006 N source Fertilizer N equivalency Calculation Fertilizer: fq fert 100 NH 3 -loss from fertilizer surface runoff ferilizer, % Manure N: fq man Organic N: 50% Inorganic N: NH 3 -loss from manure (in % of the inorganic part) surface runoff manure, % Excretion during grazing: fq ex Biological N deposition: fq biol Atmospheric N deposition: fq atm Nett mineralization: fq nmin 10% of total N excreted during grazing 100 of total fixed N 50 % of total deposited N 75% from the N mineralisation from peat soils Assumption: all manures contain of 50% organic N ( In the calculations it is assumed that the N mineralization from manure N in the second year and later is equal to the manure N that is immobilized in soil organic matter. IIB. The total amount of plant-available N = fertilizer * fq fert + manure N * fq man + excretion during grazing * fq ex + biological N deposition * fq boil + atmospheric N deposition * fq atm + nett mineralization * fq nmin III. Balanced N fertilization IIIA. For a balanced N fertilization: the total supply of plant-available N is equal to the total N demand of the crop. If the amount of plant-available N is smaller than the N demand of the crop, the crop yield may decline in time (depends on then extent of the N mineralization), but the risk on N leaching decreases. For the Nitrate Directive, a N supply that is less than the N demand is acceptable. Thus, on NUTS II level and NVZ level: the total amount of plant-available N the total N demand of the crop. IIIB. If the amount of plant-available N is higher than the crop demand, less N must be applied in order to achieve balanced N fertilizer application. The first step is to decrease the N fertilizer input. However, most farmers always will apply some fertilizer and they will not only apply manure (e.g. because they do not have the equipement, manure is not easily available, they are afraid of seeds of weed in manure etc.). The following manure acceptance factor are assumed: For fodder production (including grassland) the minimum application rate fertilizer N amounts to 0% of the fertilizer application in 2000, i.e. it is possible that these crops are only fertilized with manure.. Alterra-Concept 15 november task 1.doc 23

24 For all other crops: the minimum application rate fertilizer N amounts to 50% of the fertilizer application in 2000 If a balance N fertilization is still not achieved after a reduction of N fertilizer, the application rate of manure N is reduced. The excess manure is treated and removed from agriculture. Summarizing: The total N demand of the crop is calculated (ID) The total amount of plant-available N is calculated (IIB) On NUTS II or NVZ level: the total amount of plant-available N the total N demand of the crop. If the total amount of plant-available N > total N demand of the crop, the amount of fertilizer N is reduced with a crop dependent factor. If a balance N fertilization is still not achieved after a reduction of fertilizer application, the application rate of manure N is reduced. The excess manure is treated and removed from agriculture. Maximum manure N application rate The total amount of manure N (including excretion during grazing) may not exceed 170 kg N/ha or the value for derogation (e.g 250 kg N per ha for grassland in the Netherlands and 230 for Denmark). The following approach is chosen: For situations without a derogation: i) The total amount of soil-applied manure and N excreted during grazing is calculated per NUTS II region. ii) The average manure application rate in kg N per ha agricultural land is calculated per NVZ. iii) If the average amount exceeds 170 kg N per ha, manure is transported to other NUTS II regions in the specific country (=evenly distributed over the other NUTS II regions). iv) If there is an excess (i.e. if the average manure production in a country is higher than 170 kg N per ha), the remaining manure is treated and removed from agriculture. v) The change in manure application in a NVZ is counterbalanced with mineral N fertilizer, on basis of fertilizer equivalencies (see above). So the amount of plant-available N remains equal. Ideally, this measure is combined with the measure of balanced N fertilizer application. In situation with a derogation: 24 Alterra-Concept 15 november task 1.doc

25 CONCEPT September 2006 Because the derogation is country-specific, also calculations are country-specific. In 2006, two countries have a derogation: Denmark and the Netherlands. Possibly, the number of countries with a derogation increases. Denmark Denmark has a derogation for 230 kg N per ha manure N (including N excreted during grazing) for farms at which the area with crops with a high N demand is larger than 70 percent. These crops include grassland, fodderbeet, and grass as winter crop. The derogation only applies to about 5% of agricultural soils in Denmark and to about 6% of the total N in animal manures. The derogation is limited to existing grassland farmers and the milk quota will limit extensions to other areas. In MITERRA-EUROPE the following assumptions and calculations are made: the 5 percent of the agricultural area is evenly distributed over NUTS II regions the derogation of 230 kg N per ha applies only for grassland The Netherlands In the Netherlands farms with a least 70% grassland can apply for a derogation of 250 kg manure N per ha. The derogation only applies for manure from cattle. The remaining part is mainly silage maize. It is assumed that farms that apply for a derogation have on average 80% grassland and 20% maize. This would mean that if at all grasslands 250 kg N per ha is applied, also 250 kg N per ha can be applied at maize at an area of 0.20*total grassland area. However, the extensively managed farms will not apply for a derogation, so only on part of the grassland (and maize land) 250 kg N per ha is applied. At the remaining part, less than 170 kg N per ha is applied. There are now (in 2006) not yet figures about that the area that has applied for derogation. In the derogation request, it was expected that around 25,000 farms (from a total of 75,000 farms in the Netherlands), covering around 900,000 ha of agricultural area (from a total of 2,000,000 ha), will apply for a derogation. If it assumed that this is covered by 80% grassland and 20% maize land, the total area of grassland in the Netherlands to which 250 kg N per ha is applied is ha (72% of grassland area) and this means that at ha maize land (90% maize land area 250 kg N per ha is be applied. It assumed that application of derogation is equal for all soil types and NUTS II regions, so that at 72% of the grassland area and at 90% of the maize land area of NUTS II regions 250 kg manure N can be applied. The manure application rate in the other part of the agricultural area should be less or equal to 170 kg N per ha. The calculations (including distribution of excess manure over NUTS II regions) are the same as for the situation without derogation. Other countries Alterra-Concept 15 november task 1.doc 25

26 It is known in 2006, that also other countries think about a derogatie (e.g. Ireland, Germany, Belgium). For a prediction of a full implementation of the Nitrate Directive, assumptions must be made of derogation request. The following assumptions are made in MITERRA-EUROPE: only countries with NUTS II regions in which the average manure application (including N excreted during grazing) is higher than 170 kg N per ha apply for a derogation. It is assumed that a derogation is only given for grassland, because of its high N uptake capacity. It s assumed that a derogation is only given for the NUTS II regions in which manure application rate is higher than 170 kg N per ha. It is assumed that the derogation applies to only 50% of the grassland within the NUTS II regions in which manure application rate is higher than 170 kg N per ha. The total application rate of manure on grassland with derogation is 250 kg N per ha. No fertilizer and manure application in winter and wet periods Assumptions for manure the availability of manure N for crops (fertilizer equivalency) increases, so that the amount of required N fertilizer decreases the emission of NH 3 and CH 4 from stored manure increases Limitation to fertilizer application on steeply sloping grounds The measure is only applicable for the area within a NUTS II region or NVZ with a certain slope class: Steep slope: 50% reduction of N fertilizer and manure in comparison to application rate in 2000 in that area Intermediate: 25% reduction of N fertilizer and manure in comparison to application rate in 2000 in that area Slight 5% reduction of N fertilizer and manure in comparison to application rate in 2000 in that area No no reduction Manure storage with minimum risk on runoff and seepage After fully implementation of this measure it is assumed that: All liquid manure storages without concrete floor are converted into liquid storage with concrete floor 26 Alterra-Concept 15 november task 1.doc

27 CONCEPT September % of solid manure storages without concrete floor are converted into solid storage with concrete floor 50% of solid manure storages without cover are converted into solid storage with cover Type of manure system Concrete floor Cover Leaching fraction, % of stored N Liquid/slurry no no 20 yes 15 yes no 0 yes 0 Solid no no 10 yes 2 yes no 5 yes 0 Unmanaged no no 50 Appropiate fertilizer and manure application techniques, including split application of nitrogen This technique leads to a higher efficiency of applied nitrogen and a lower leaching below rooting zone. It assumed that after full implementation of this technique (all crops): The over-fertilisation factor decreases with 25% The leaching fraction below rooting zone decreases with 10% Bufferstrips near water courses Bufferstrips near water courses decrease leaching and surface runoff to the surface water. The effectivness of the bufferstrip depends on the slope of the soil, width of the bufferstrip, hydrology, crop type (in and outside the bufferstrip), soil type. There is not much information available on the effectiveness of bufferstrips. The following assumptions are made for a 100 meter bufferstrip. The bufferstrips are not fertilized with fertilizer and manure, but are not grazed and N fixation can occur. Reduction of runoff fraction: 50% Reduction of leaching to surface water 50% The rest is denitrified. It assumed that 10% of the extra denitrification is emitted as N2O. It s assumed that fallow and set-aside land are moved to the bufferstrip area, so that nett no change in the total agricultural land occurs. We only consider wet bufferstrips of 100 meter in riparian zones neat large surface waters in agricultural regions. Alterra-Concept 15 november task 1.doc 27

28 Table. Total area of surface waters and area of surface waters in agricultural regions and the length of the banks in EU countries. Area of surface water, ha Length of banks of surfacewater, km total agricultural total in agricultural region Austria Belgium Bulgaria Switzerland Cyprus * * * * Chech_Republic Germany Denmark Estonia Spain France Greece Croatia Hungary Ireland Italy Lithuania Luxembourg Latvia Malta * * * * Netherlands Poland Portugal Rumania Sweden Slovania Slovakia Turkey UK Alterra-Concept 15 november task 1.doc

29 CONCEPT September 2006 Figure. Map of Poland showing presence of surface water. Growing winter crops Growing winter crops will result in i) less nitrogen leaching below rooting zone, ii) less surface run-off, and iii) less requirement of fertilizer N in the following year. However, it is not possible to grow winter crops after all arable crops (because of late harvest times or other crop management aspects). The following assumptions are made: winter crops can be grown after 25% of the arable crops, winter crops reduce the fractions of nitrogen leaching from rooting zone with 25% winter crops reduce the surface runoff fractions with 25% in intensive NUTS II regions (i.e. with an average N surplus > 100 kg N per ha), the N fertilizer application can be reduced with 25 kg N per ha per year after growing winter crops In Central/East Europe and Scandinavian countries the figures are different, because of the cold conditions in winter Alterra-Concept 15 november task 1.doc 29

30 after 15% of the arable crops in a NUTS II region, winter crops can be grown winter crops reduce fraction nitrogen leaching from rooting zone with 10% winter crops reduce surface runoff fraction with 10% in intensive NUTS II regions (i.e. with an average N surplus > 100 kg N per ha), the N fertilizer application can be reduced with 10 kg N per ha per year after growing winter crops Combination of effects It is assumed that the effectiveness of measures decreases when more measures are taken that affect the same parameter (such as the leaching fraction). It is assumed that the effectiveness decreases in the order: 1, 0.5, 0.25, etc. Thus, if 4 measures are taken that each reduce the leaching fraction with 25%, the total effect is: 1*25% *25% *25% *25% = 1.61*25% = 40.25% Qualitative estimation of the costs In task 3 of the service contract an in depth analyses (including economic consequences) of promising packages of measures are carried out. In table an qualitatieve estimate is given of the costs of different nitrate measures. Table. Qualitative indication of costs of measures to decreases nitrate leaching Measure Costs maximum manure N application standard of Transport costs, costs for processing manure 170 kg N per ha (except where a derogation and/or costs for decreasing number of animals applies) balanced N fertilizer application based on soil Farmer has to buy less fertilizer; negative costs. analysis, expected N mineralisation, weather conditions, and crop demand no fertilizer and manure application in winter and wet periods Limitation to fertilizer application at steep slopes Manure storage with minimum risk on runoff and seepage appropiate fertilizer and manure application techniques bufferstrips near water courses growing winter crops Cost are high if the farmer has to built a new manure storage. In intensive areas farmers have to buy less N fertilizer. Less fertilizer use, but probably some decline in yield. Total cost are about neutral Cost for adaptations of manure storage (or building a new storage). In intensive areas farmers have to buy less N fertilizer. Cost for new techniques. Depends on how it is implemented. The costs are relatively low if set-aside or fallow land is spatially redistributed. If agricultural land is transformed into non-agricutural land, the costs can be high. Costs for seed and extra soil cultivation. In intensive areas farmers have to buy less N fertilizer. 30 Alterra-Concept 15 november task 1.doc

31 CONCEPT September Phosphorus leaching MITERRA-EUROPE does not calculate phosphorus leaching to surface-waters, because detailed data of the phosphorus status of the soil and a chemical soil model is required for this type of calculations. This is not achievable for this surface contract. However, it is well-known that the risk on phosphorus leaching is highest for agricultural systems with a phosphorus surplus, i.e. the input of phosphorus via fertilizer and manure to soil is higher than the removal of phosphorus via harvested crop. Two types of measures to reduce the risk on phosphorus leaching are included: i) in NUTS II regions with an average phosphorus surplus, the average phosphorus input to the soil is decreased at such an extent that input equals the output. Firstly, this is done by decreasing the phosphorus fertilizer input with 50%, but if this is not sufficient also the amount of manure that is applied in the regions is decreased (by increasing export of manure to other NUT II regions within the country). ii) in NUTS II regions with a high average phosphorus surplus the average phosphorus input to the soil is decreased at such an extent that input is smaller than the output. Firstly, this is done by decreasing the phosphorus fertilizer input, but if this is not sufficient also the amount of manure that is applied in the regions is decreased (by increasing export of manure). The idea behind this measure is that the soils in regions with a high phosphorus surplus, have a high phosphorus status (assuming that the input was also high in the past) and the phosphorus concentrations in these soils can only be considerably reduced when there is a negative phosphorus balance. The data on phosphorus fertilizer input and crop removal of phosphorus are derived from CAPRI. 2.4 Temporal and spatial scales The reference year of MITERRA-EUROPE is the year Measures that are implemented will start from the situation in 2000 (see also subtasks 1.2, 1.3 and 1.4). MITERRA-EUROPE calculates emissions on NUTS-2 level, the level of nitrate vulnerable zones, and country level. In terms of the crop allocation within (about 400) NUTS-2 regions, the CAPRI Dynaspat project offers the possibility to map the cropping pattern into (about 25000) so called Homogenous Spatial Mapping Units (HMSUs). Soil and climatological data at NUTS-2 level are derived from JRC and Alterra. Maps of Nitrate Vulnerable Zones (NVZ) are available at Alterra from service contract 2005/409860/MAR/B1). In the kick-off meeting, Dr. Cortellini of DG ENV.B1 has stated that these maps are also available for the current project. In figure the NVZ in Eu-15 are indicated. Alterra-Concept 15 november task 1.doc 31

32 Figure NVZ in EU-15. The RAINS/GAINS model calculates emissions on a national scale, using activity data and emission factors on a national scale. The deposition is calculated on a grid level using an atmospheric transport model and the RAINS/GAINS emission data on a national scale. The following approach is used to transfer the results on HMSUs, NUTS-2 level and NVZ zones in MITERRA-EUROPE to the country/grid level in RAINS/GAINS: an overlay of the maps of HMSUs (which aggregate to NUTS-2 regions) and NVZ is made, by which the percentage of the area of the HMSUs and NUTS-2 regions (and thereby the countries) covered by NVZ is known; measures of the action programmes of the Nitrate Directive are implemented in the NVZ and underlying HMSUs; the effect of the measures in NVZ on activity data (e.g use of N fertilizer, method of manure application) and emissions are calculated; the results for the NVZ are scaled up to HMSUs, NUTS-2 level and country level, using the percentages of area covered by NVZ; the results on the country level are transfered to RAINS/GAINS (e.g. implementation of the action programmes in NVZ of certain country results in a decrease of the N fertilizer use of certain percentage in that country); RAINS/GAINS calculate the NH 3 emissions on the country level and these results are used in the atmospheric model of RAINS/GAINS to calculate deposition on a grid level. 32 Alterra-Concept 15 november task 1.doc

33 CONCEPT September 2006 In MITERRA-EUROPE the 25 member countries of the EU are included, plus Bulgaria, Romania, and Croatia 2.5 Scenarios Reference year 2000 The calculations for the references year 2000 use activity data of CAPRI (based on Eurostat), the implementation of ammonia abatement techniques form RAINS and the implementation of measures reducing nitrate leaching from service contract 2005/409860/MAR/B1. The implementation of the different nitrate measures in 2000 are estimated from the action programmes of the member states (Annex 10) Measures taken after full implementation of the Nitrate Directive Assumptions are made for the different countries of the packages of measures that countries have to take in their NVZ s for full implementation of the Nitrate Directive (after consultation of European Commission) Measures taken after implementation of the Water Framework Directive (WFD) It is assumed that all measures that have to be taken to implement the Nitrate Directive in NVZ, have to be taken in the whole area for implementation of the WFD. Moreover, it is well-known that the risk on phosphorus leaching is highest for agricultural systems with a phosphorus surplus, i.e. the input of phosphorus via fertilizer and manure to soil is higher than the removal of phosphorus via harvested crop. Two types of measures to reduce the risk on phosphorus leaching are included: i) in NUTS II regions with an average phosphorus surplus, the average phosphorus input to the soil is decreased at such an extent that input equals the output. Firstly, this is done by decreasing the phosphorus fertilizer input with 50%, but if this is not sufficient also the amount of manure that is applied in the regions is decreased (by increasing export of manure to other NUT II regions within the country). ii) in NUTS II regions with a high average phosphorus surplus the average phosphorus input to the soil is decreased at such an extent that input is smaller than the output. Firstly, this is done by decreasing the phosphorus fertilizer input, but if this is not sufficient also the amount of manure that is applied in the regions is decreased (by increasing export of manure). The idea behind this measure is that the soils in regions with a high phosphorus surplus, have a high phosphorus status (assuming that the input was also high in the past) and the phosphorus concentrations in these soils can only be considerably reduced when there is a negative phosphorus balance. Alterra-Concept 15 november task 1.doc 33

34 2.5.4 Description of the three RAINS scenarios The following RAINS scenario s are assessed: o Baseline scenario ( ); is based on a defined economic development made by CAPRI-Eurocare-report 2003 (EEA outlook study). o National scenario, have different defined economic development (and therefore different animal numbers). o NEC scenario. NEC scenario: implementation of NEC directive 34 Alterra-Concept 15 november task 1.doc

35 CONCEPT September Results and Discussion All results presented in the chapter must be considered as preliminary results. 3.1 Effect on EU level In table the effects of full implementation of different ammonia and nirate measures on emissions on EU-15 or EU-25 are presented. This Table. Change (in %) in emission compared to situation in 2000, assuming that no measures were taken Measure NH 3 NO 3 N 2 O EU-25 EU-15 EU-25 Ammonia Biofiltration Low ammonia application - high Covered storage - high Stable adaptation Low nitrogen feed Incineration Urea substitution Package Nitrate Balanced fertilization Maximum manure application Limit on slopes Optimal storage Application techniques No winter application Winter crops Package Reference year Maps In this paragraph maps of calculations for the reference year 2000 are presented. All data are expressed in kg per ha agricultural land per NUTS region. Alterra-Concept 15 november task 1.doc 35

36 Figure. Average application rates of mineral N fertilizer and manure on agricultural soils in NUTS II regions in 2000 (kg per ha). 36 Alterra-Concept 15 november task 1.doc

37 CONCEPT September 2006 Figure. Average N surplus and NH3 emission in NUTS II regions in 2000 (kg per ha). Alterra-Concept 15 november task 1.doc 37

38 Figure. Average surface runoff and N leaching in NUTS II regions in 2000 (kg per ha). (only EU 15, because soil data were not yet available). 38 Alterra-Concept 15 november task 1.doc

39 CONCEPT September 2006 Figure. Average N leaching from manure storage and nitrous oxide emissions in NUTS II regions in 2000 (kg per ha). Alterra-Concept 15 november task 1.doc 39

40 Figure. Average methane emission and phosphorus surplus in NUTS II regions in 2000 (kg per ha). 40 Alterra-Concept 15 november task 1.doc

41 CONCEPT September Effects of ammonia measures on emissions of ammonia, nitrate, nitrous oxide, methane and NOX Maps In this paragraph maps of calculations after implementation of ammonia abatement techniques according to RAINS are presented. Alterra-Concept 15 november task 1.doc 41

42 Figure. Average ammonia emission and N surplus in NUTS II regions in 2000 after taking a package of ammonia abatement techniques according to the RAINS model (kg per ha). 42 Alterra-Concept 15 november task 1.doc

43 CONCEPT September 2006 Figure. Average nitrous oxide and methane in NUTS II regions in 2000 after taking a package of ammonia abatement techniques according to the RAINS model (kg per ha). Alterra-Concept 15 november task 1.doc 43

44 Figure. Average leaching from manure storage and surface runoff in NUTS II regions in 2000 after taking a package of ammonia abatement techniques according to the RAINS model (kg per ha). 44 Alterra-Concept 15 november task 1.doc

45 CONCEPT September 2006 Figure. Average N leaching below rooting zone in NUTS II regions in 2000 after taking a package of ammonia abatement techniques according to the RAINS model (kg per ha). Alterra-Concept 15 november task 1.doc 45

46 3.3.2 Effect of measures in comparison to 2000 In the following figures the effects of implementation of a package of ammonia abatement techniques are presented. On the x-axis the emission in each NUTS 2 region in 2000 is plotted against the emission after taking the measures (y-axis). Each dot in the figure is a NUTS 2 region. 46 Alterra-Concept 15 november task 1.doc

47 CONCEPT September NH3 emission, kg N/ha: all RAINS measures NH3 emission, kg N/ha: year N2O emission, kg N/ha: all RAINS measures N2O emission, kg N/ha: year 2000 Figure. Emission in year 2000 (x-axis) plotted against emission after implementation of package in ammonia abatement techniques (y-axis). The 1 : 1 line is indicated. The dots are NUTS II regions. Alterra-Concept 15 november task 1.doc 47

48 350 CH4 emission, kg/ha: all RAINS measures CH4 emission, kg/ha: year 2000 NO3 leaching, kg N/ha: all RAINS measures NO3 leaching, kg N/ha: year 2000 Figure. Emission in year 2000 (x-axis) plotted against emission after implementation of package in ammonia abatement techniques (y-axis). The 1 : 1 line is indicated. The dots are NUTS II regions. 48 Alterra-Concept 15 november task 1.doc

49 CONCEPT September Effect of nitrate measures on emissions of ammonia, nitrate, nitrous oxide, methane and NOX Maps Effect of measures in comparison to 2000 In the following figures the effects of implementation of balanced fertilization as measure to decrease nitrate leaching is presented. On the x-axis the result in each NUTS 2 region in 2000 is plotted against the result after taking the measures (y-axis). Each dot in the figure is a NUTS 2 region. 150 manure application rate, kg N/ha: balanced fertilization manure application rate, kg N/ha: year 2000 Alterra-Concept 15 november task 1.doc 49

50 150 nitrogen surplus, kg N/ha: balanced fertilization nitrogen surplus, kg N/ha: year N2O emission, kg N/ha: balanced fertilization N2O emission, kg N/ha: year 2000 Figure. N application in year 2000 (x-axis) plotted against application rate at balanced N fertilization (y-axis). The 1 : 1 line is indicated. The dots are NUTS II regions. 50 Alterra-Concept 15 november task 1.doc

51 CONCEPT September N leaching, kg N/ha: balanced fertilization N leaching, kg N/ha: year 2000 Figure Emission in year 2000 (x-axis) plotted against emission at balanced N fertilization (y-axis). The 1 : 1 line is indicated. The dots are NUTS II regions. Alterra-Concept 15 november task 1.doc 51

52 Change in %, in comparison to year 2000 RAINS measures low N feed biolfiltration covered storage incineration application all Average ammonia emission in NUTS 2 regions, kg N per ha Change in %, in comparison to year RAINS measures low N feed biolfiltration covered storage incineration application all Average nitrate leaching in NUTS 2 regions, kg N per ha Change in %, in comparison to year 2000 RAINS measures low N feed biolfiltration covered storage incineration application all Average nitrous emission in NUTS 2 regions, kg N per ha Figure. Effect of implementation of ammonia measures on ammonia emission (upper figure), nitrate leaching (middle figure),and nitrous oxide emission (lower figure), compared to the situation in which no measures were taken (activity data from 2000). 52 Alterra-Concept 15 november task 1.doc

53 CONCEPT September Results of scenarios Year Full implementation of Nitrate Directive Water Framework Directive RAINS Baseline scenario RAINS National scenario RAINS NEC scenario 3.6 Discussion Alterra-Concept 15 november task 1.doc 53

54 References 54 Alterra-Concept 15 november task 1.doc

55 Annex 1. Nitrate measures affecting ammonia emission (input for RAINS scenarios) Nitrate measures affecting ammonia emissions Gerard Velthof, Diti Oudendag & Oene Oenema, Alterra, Introduction In the framework of the revision of NEC directive, a new baseline scenario will be developed by IIASA in summer 2006 for calculations with RAINS. This new baseline will also include new agriculture projections integrating the measures taken by the Member States in order to meet the objectives of the Nitrate Directive. Alterra has made an assessment of the effects of measures that have to be taken to implement the Nitrate Directive on ammonia emission. This assessment is part of the Service Contract No /2005/422822/MAR/C1- Integrated measures in agriculture to reduce ammonia emissions. Measures in the Nitrate Directive Two types of strategies to decrease nitrate pollution of groundwater and surface waters can be distinguished within the Nitrate Directive: (i) (ii) codes of good agricultural practice for the whole country with the aim of providing for all waters a general level of protection against pollution. These codes of good agricultural practice have to be implemented by farmers on a voluntary basis (including provision of training and information for farmers). See Annex 9 for description of Codes of Good Agricultural Practice (i.e. the Annex II of the Nitrate Directive). action programmes in respect of designated vulnerable zones, including the measures of Annex III of the directive and the measures for the Codes of Good Agricultural Practice (see Annex 9). For most measures only outlines are given (see Annex 9) and the countries can fulfil these measures in different ways (Annex 10). The measures of the action programmes have to be taken in Nitrate Vulnerable Zone (NVZ). RAINS calculates ammonia emissions on a country level, because the targets of the NEC directive are set on a national level. This indicates that nitrate measures only significantly affect national ammonia emissions if countries have designated a significant percentage of their area as NVZ. Countries of the EU-15 which have designated their entire area as NVZ are Austria, Denmark, Germany, Finland, Ireland, Luxembourg, and the 55

56 Netherlands. Countries of the EU-15 with more than 25% of their area as NVZ are Belgium, United Kingdom, and France. It is suggested that for all other countries (i.e. with less than 25% of the area as NVZ), implementation of the Nitrate Directive does not significantly affect ammonia emission on a country level. Most measures required to meet the targets of the Nitrate Directive affect the management of fertilizer and manure. However, only part of the measures may have a significant impact on the ammonia emission and are important for the scenarios for the NEC Directive. It is expected that the measures dealing with following topics may have a direct effect on national ammonia emissions and it suggested including these measures in the RAINS baseline scenario: 1. closed periods and storage capacity 2. application standards of manure 3. In paragraph 5 a short description is given of other nitrate measures that may affect ammonia emission and greenhouse gas emission. It is probably not achievable to include these measures in the RAINS baseline scenario in a short time. Citation Annex II Nitrate Directive (see Annex 9) The measures shall include rules relating to: 1. periods when the land application of certain types of fertilizer is prohibited; 2. the capacity of storage vessels for livestock manure; this capacity must exceed that required for storage throughout the longest period during which land application in the vulnerable zone is prohibited, except where it can be demonstrated to the competent authority that any quantity of manure in excess of the actual storage capacity will be disposed of in a manner which will not cause harm to the environment; In Annex 10 data are given on the periods in which it is forbidden to apply manure to soils and of the required storage capacity of manure, according to the draft summary report of implementation of the Nitrate Directive in The following estimate is made to be used in the RAINS scenario: no manure is applied to the soil in a period of 5 months (15 September and 15 February) in all countries of EU 25. This means that the manure is stored for 5 months during autumn/winter. It depends on the current assumptions in RAINS of storage time of manure (and predictions for the future in the baseline scenario), whether this measure affects the baseline scenario. Application standards of manure 56

57 Citation Annex III Nitrate Directive (see Annex 9)..These measures will ensure that, for each farm or livestock unit, the amount of livestock manure applied to the land each year, including by the animals themselves, shall not exceed a specified amount per hectare. The specified amount per hectare be the amount of manure containing 170 kg N The Nitrate Directive limits the maximum application standard of manure to 170 kg N per ha. However, larger amounts of manure may be applied ( derogation ) if countries can justify higher application standards on basis of several criteria, such as a high nitrogen uptake by the crop (see Annex III of Nitrate Directive; Annex 9. At this moment, the Netherlands and Denmark have a derogation to use more manure on part of their grassland). Currently also AU has a derogation and most probably also Belgium (Wallonia), Ireland and Germany will have a derogation in the near future. This measure only slightly affects ammonia emissions in case the manure is transported from farms with an excess of manure (> 170 kg N per ha) to farms in which there is still space to use more manure (< 170 kg N per ha). Manure transport between farms will probably be the most common respons of farmers to this measure. The maximum application standard of 170 kg N per ha holds for individual farms, so that manure transport may even occur in regions with an average low manure application rate. However, in areas (or countries) with a high density of animals, the manure production may exceed 170 kg N per ha and there may be no space to transport manure to other farms in the region. The remaining solutions in these area are: i) treatment of manure (including burning) and removing the nitrogen from agriculture and/or ii) decreasing the number of animals, and especially those of land-less intensive farming systems, such as part of the pig and poultry farming systems. These measures affect ammonia emissions and may be included in the RAINS scenario. The current version of MITERRA-EUROPE was used to calculate the average application rates of manure to soil (including N excreted during grazing) in NUTS regions of EU-25. These calculations were based on CAPRI and RAINS data on animal numbers, nitrogen excretion per animal, gaseous nitrogen losses from housings and storage, and grazing days. In table 2 the NUTS II (for UK NUT I) regions are presented with average manure application rates of more than 100 kg N per ha. All other NUTS II regions in EU-25 have manure application rates of less than 100 kg N per ha. Table 2 indicates that both in the Netherlands and in Flanders it will be difficult to distribute the manure over farms, so that the application rates of all farms will be less than 170 kg N per ha. In these regions, treatment of manure may increase in the future. Treatment (or burning) and transport of pig manure is more expensive than of poultry manure. It is expected that the number of pigs will decrease much more than that of poultry in case the number of animals has to be decrease to fulfil the targets of the Nitrate Directive,. However, current projections of the number pigs in e.g the Netherlands are based on economics, so that these projections can not be used in scenarios as an effect of the Nitrate Directive (otherwise there may be an overlap with the CAPRI projections of developments in agriculture). It is suggested for the RAINS baseline scenario that for the Netherlands and Flanders part of the poultry manure is burnt and part of the pig manure is treated. Before estimates of these amounts are made, information is needed whether RAINS can indeed include these 57

58 developments in the scenarios. Moreover, it is assumed that the number of pigs and poultry do not change because of implementation of the Nitrate Directive. Thus it is assumed that reduction of the manure surplus can be solved by manure transport in combination with treatment and burning of manure. 58

59 Table 2. Average application rates of manure to soil (including N excreted during grazing) in NUTS regions of EU-25 in descending order. Only regions with average application rates of more than 100 kg N per ha are presented. Results of MITERRA EUROPE Country Region (NUTS I or II) Average soil application of manure, kg N per ha the Netherlands Noord-brabant 314 the Netherlands Gelderland 307 Belgium Prov. Antwerpen 304 the Netherlands Utrecht 302 the Netherlands Overijssel 293 Belgium Prov. West-vlaanderen 252 the Netherlands Friesland 249 Belgium Prov. Oost-vlaanderen 214 the Netherlands Limburg (nl) 203 Spain Cantabria 183 United Kingdom UKN0 178 Malta MT 167 United Kingdom UKK0 166 Belgium Prov. Limburg (b) 164 the Netherlands Zuid-holland 164 Greece Ipeiros 163 United Kingdom UKL0 162 United Kingdom UKD0 156 Belgium Prov. Luxembourg (b) 147 United Kingdom UKG0 145 the Netherlands Drenthe 145 Portugal Região Autónoma Dos Açores 142 the Netherlands Noord-holland 140 Belgium Prov. Liège 136 Italy Lombardia 134 Spain Principado De Asturias 133 United Kingdom UKE0 129 Portugal Região Autónoma Da Madeira 127 Ireland Southern And Eastern 124 Cyprus CY 120 the Netherlands Groningen 119 France Bretagne 117 Belgium Prov. Hainaut 112 Spain Galicia 109 Ireland Border, Midland And Western 109 Germany Schwaben 108 United Kingdom Tees Valley And Durham 106 Spain País Vasco 105 United Kingdom UKF0 104 Germany Münster 101 Belgium Prov. Namur 101 United Kingdom UKJ

60 Germany Weser-ems 101 Storage of manure A code or codes of good agricultural practice with the objective of reducing pollution by nitrates..the capacity and construction of storage vessels for livestock manures, including measures to prevent water pollution by run-off and seepage into the groundwater and surface water of liquids containing livestock manures and effluents from stored plant materials such as silage;. Member must change part of their manure storage systems in order to reduce nitrogen leaching (and seepage) from stored manure to ground and surface waters. However, according to the reports of implementation of the Nitrate Directive this measure did not have much attention till now. Most member states have implemented this measure already and do not report on it. It is assumed that after fully implementation of this measure: All liquid manure storages without concrete floor are converted into liquid storage with concrete floor 50% of solid manure storages without concrete floor are converted into solid storage with concrete floor 50% of solid manure storages without cover are converted into solid storage with cover All unmanaged manure systems are converted into managed systems. It is assumed to 50% of unmanaged systems is converted into solid manure systems with a cover and concrete floor and 50% into liquid manure systems with a cover and concrete floor Only the changes in cover will significantly affect ammonia emissions, but probably an increase of the number of covered storages is already predicted in the RAINS scenario. Changes in the presence of concrete floors affect ammonia emission much less than the presence of a cover. Therefore, it is suggested not to implement changes of the presence of concrete floors in the RAINS scenario. However, the presence of a concrete floor may an important measure to decrease leaching from stored manure. In MITERRA-EUROPE, estimates of covers of liquid and solid manures in the member states are derived from RAINS. Estimates of the presence of manure storage systems with concrete floors are derived from expert judgement. In table 2, estimates for several new member states are presented.. 60

61 Table 2. Estimates of the presence of a cover and concrete floor in manure storage systems in new member states (First draft). Type of Concrete Cover Presence of manure system in a country, % of all stored manure floor manure system Poland Czech Republic Slovakia Lithuania Latvia Estonia Liquid/slurry no no yes yes no yes Solid no no yes yes no yes Unmanaged no no Other measures Balanced nitrogen fertilization There are some possible indirect effects of nitrate measures on ammonia emission. The Nitrate Directive includes a measure of balanced nitrogen fertilization, i.e. the total input of plant-available nitrogen via fertilizer, manure, biological nitrogen fixation, mineralization, and atmospheric deposition must be tuned to the nitrogen demand of the crop. In intensively managed grasslands, lower nitrogen application rates decrease nitrogen contents of the grass, which results in a lower nitrogen excretion from cattle and a lower potential for ammonia emission from both stored cattle manure and from grazing. For RAINS this would mean that the nitrogen excretion of cattle would be lower after implementation of this measure. This depends on the current nitrogen input to grassland and the yields that can be obtained in the different countries (i.e. the nitrogen demand of grassland differs between countries). Moreover, there are some other developments, such as changes in milk production per cow and changes in ratio between grass and other fodder crops, that also affect the nitrogen excretion of cattle. The effect of lower nitrogen application rates on the nitrogen content of maize or other fodder crops is much smaller than that of grassland. In the Netherlands, nitrogen excretion of dairy cattle did not clearly change the last years, although the nitrogen application rate to grassland significantly decreased. This is probably due to an increase in milk production per cow. Because of the many uncertainties of the effects of balanced nitrogen fertilization on nitrogen excretion and ammonia emission, it is recommended no to include this measure in RAINS at this stage. This may be done later if a more clear picture is obtained of the implementation of this measure in the different countries, its effect on nitrogen content of grass, nitrogen excretion by cattle, and ammonia emission during grazing and manure storage. 61

62 Measures affecting nitrous oxide emission Most of the measures of the Nitrate Directive may affect the emission of nitrous oxide, especially those measures that reduce N fertilizer use. However, a complete and tested version of MITERRA-EUROPE is needed to accurately estimate the impact of full implementation of the Nitrate Directive on fertilizer use in EU countries. Such version is probably only available in the second half of August and too late to be used for the RAINS baseline scenario. The focus is only on measures affecting ammonia emission, because these are the important measures for the NEC directive. 62

63 Annex 2. Detailed information on input data 63

64 Annex 3. Calculation of leaching in MITERRA-EUROPE Gerard Velthof, Diti Oudendag, Oene Oenema,. Introduction MITERRA-EUROPE calculates NH 3, N 2 O, NO x, and CH 4 emissions to the atmosphere and N leaching to ground and surface water on a regional level (NUTS2) in Europe. The major aim of the MITERRA-EUROPE modelling tool is to assess the impact of ammonia policy (including NEC directive) on nitrogen leaching, and of nitrate policy (Nitrate Directive, Water Framework Directive) on ammonia emission. The Nitrate Directive aims at decreasing the nitrate leaching from agricultural sources to ground and surface waters. This includes the leaching of nitrate from fertilizer and manure applied to land. Special attention in the Codes of Good Agricultural Practice of the Nitrate Directive is paid to prevent/decrease the nitrogen leaching from stored manure and manure and fertilizers applied to sloping soils. Therefore, a module is included in MITERRA- EUROPE to estimate leaching from stored manure and from sloping soils (via runoff). The purpose of the notice is to briefly describe the three modules that assess the leaching of nitrate from agricultural sources, i.e. i) leaching below rooting zone, ii) leaching from surfacerunoff, and iii) leaching from stored manure : i) N leaching and surface run-off from stored manure. Manure that is stored in the open air without a concrete floor is susceptible to leaching and runoff to groundwater and surface water. In the Nitrate Directive, special attention is paid to decrease the risk on N leaching from stored manure. In MITERRA-EUROPE a method is included that estimates leaching from stored manure, using data on manure storage type in the different countries (paragraph ). ii) surface runoff The risk on surface runoff of applied fertilizer and manure is especially high for sloping soils, although some runoff may also occur during wet conditions in flat areas. Surface runoff is calculated on basis of slope, rainfall and crop parameters. The fate of the N that has been leached via runoff is not included in MITERRA-EUROPE. In paragraph., the method to calculate surface runoof is described in detail. iii) leaching below the rooting zone. The leaching of nitrogen below the rooting zone is calculated using data of the soil nitrogen surplus and some location specific factors (including soil type, organic matter content, weather conditions). The fate of the nitrogen that has been leaching below the rooting zone is not calculated with MITERRA-EUROPE. Part of the nitrogen will leach to deeper groundwater, part to surface water, and part is denitrified. In paragraph., the method to calculate leaching below the rooting zone is described in detail. 64

65 Overview of MITERRA-EUROPE In figure 1, MITERRA-EUROPE is schematically represented. It is indicated in this scheme that leaching from stored manure is calculated from the amount of nitrogen excreted by housed animals. The leaching fractions depend on manure storage systems. The surface runoff is calculated from the manure (including N excreted during grazing) and fertilizer applied to soil, after correction from NH 3 and N 2 O emissions. The nitrogen surplus is calculated from the inputs of nitrogen and the output via crop removal. The nitrogen surplus is an indicator for losses via leaching and denitrification to N 2. The leaching and denitrification is calculated from the nitrogen surplus and leaching or denitrification fractions. The fractions depend on soil properties, crop, and environmental conditions. Also other in models leaching or denitrification factors are used to estimate leaching of N to ground and surface waters (de Vries et al., 2003; Schröder et al., 2006& 2006; Van Drecht et al., 2003). In MITERRA-EURPOPE N 2 O emission are calculated using IPCC emission factors, so that the results are comparable to RAINS/GAINS. Changes in soil organic nitrogen contents of the soil also affect the nitrogen surplus. In MITERRA-EUROPE changes in organic nitrogen contents of the soil are based on soil properties and nitrogen inputs. One of the measures within the Nitrate Directive demands for balanced nitrogen fertilizer application, in which the nitrogen demand of a crop is tuned to the amount of plant-available nitrogen. This includes the input of nitrogen via fertilizer and manure, but also the nitrogen mineralized from soil organic matter. The results of the calculated mineralization in MITERRA-EUROPE are also used for assessing the effect of implementation of the measure of balanced fertilization. Homogenous Spatial Mapping Units The leaching fractions for MITERRA-EUROPE are calculated on the basis of crop, soil, and climatological using the Homogenous Spatial Mapping Units (HMSUs) developed in the CAPRI Dynaspat project. In this project, a statistical approach is developed to break down data of 30 crops in about 150 European administrative regions for EU15 (NUTS 2) to HSMUs, using spatial information of the land cover/land use map (CORINE), Cover Area Frame Statistical Survey (LUCAS), soil map, digital elevation map, and climate map (see 65

66 Figure 1. Overview of the nitrogen flows and calculation order of nitrogen emissions in MITERRA- EUROPE. Mineralization/accumulation in soil organic matter Introduction Results of long-term experiments clearly show that the soil organic N content in permanent grasslands increases in time, because of the high input of crop residues and manure and the absence of soil cultivation. The accumulation of organic matter starts soon after establishment of the grass, shows an asymptotic trend and may continue for more 30 to 100 years (Hoogerkamp, 1984; Jenkinson, 1988). The N content of the grassland soil increases approximately linearly in young grasslands (<10 years), ranging from 20 to 130 kg N ha -1 year -1 (Cuttle & Scholefield, 1995; Hassink, 1994; Hoogerkamp, 1984; Tyson et al., 1990; Whitehead et al., 1990). The rate of N accumulation in soil depends on soil N content (low soil N content > high soil N content), management (high N input > low N input; grazed > cut ), and age (young > old; figure 2) but the separate effects of these factors can not be quantified yet due to lack of experimental data (Velthof & Oenema, 2001). 66

67 1.2 total N content in the 0-5 cm layer, % old grassland young grassland: high organic matter young grassland: low organic matter Figure 2. Time course of total N content in the 0-5 cm layer of old grassland (no change) and young grasslands (increase in total N) with different organic matter contents on a heavy clay soil (Hoogerkamp, 1984). After conversion of grassland to arable land, N mineralization is enhanced and the organic N content will decrease in time until an equilibrium is reached. The time of this decrease in organic N content and the organic N at equilibrium situation strongly depends on the initial organic N content of the soil, nutrient management, soil type, weather conditions and crop type. In temporary grasslands in rotation with arable crops, a period with N accumulation during the grassland period is followed by a period of net mineralization during the arable cropping period. The total N content is on average between that of permanent grassland and permanent arable land. Long-term studies clearly show the effect of land use system (permanent grassland, permanent arable land and grass-arable land rotation) on soil organic matter, i.e. the soil organic matter content increases in the order permanent arable land < rotation of grassland and arable land, grassland (Vertes et al., 2004, e.g figure 3). 4 3 OC in soil (%) 2 1 grass grass arable grass grass arable arable arable

68 Figure 3. Effect of ploughing out grass and sowing grass on soil carbon content. Data from the Rothamsted Ley-arable experiments (Johnston, 1986). Peat soils contain large amounts of organic nitrogen. This organic nitrogen may be mineralized when peat soils are drained for agricultural use. The amount of nitrogen released from drained peat is dependent on the drainage and peat type (Heathwaite 1991; Schothorst, 1977). Assumptions and calculation method. For permanent grassland, it assumed that accumulation of nitrogen occurs or that the content of soil organic N does not change. For arable land, soil nitrogen content decreases or remains constant, depending on organic matter contents. Besides land use and organic matter content (e.g. figures 2 and 3), also the temperature and nitrogen input affect the accumulation of organic nitrogen in soil organic matter. Under warm conditions, soil bacteria are more active than under cold conditions. The mineralization rate of organic matter generally increases by a factor 2 if the temperature increases by 10 o C. Therefore, the organic matter contents in soils are mostly higher in cold areas than in warm areas. The nitrogen that accumulates in soils, is derived from fertilizer, manure and other sources. In systems with low inputs of nitrogen, only small amounts of nitrogen can accumulate in soil organic nitrogen. Therefore, the nitrogen accumulation in MITERRA-EUROPE is calculated as a percentage of the soil nitrogen surplus, depending on temperature, land use, and organic matter content. The accumulation fraction are estimated on basis of expert judgement (Table 1). The remaining fraction of the nitrogen surplus is either denitrified or leached below rooting depth. Table 1. Accumulation of nitrogen in soil organic matter. Accumulation is depending on temperature, land use and C content and calculated in MITERRA-EUROPE as percentage of the nitrogen surplus. Average annual temperature Land use Total C content in the 0-20 cm layer N-accumulation in % of the N surplus < 5 0 C Grassland < 2% % 20 > 5% 2 Other < 2% 10 > 2% Mineralization: see table C Grassland < 2% % 10 > 5% 1 Other < 2% 5 > 2% Mineralization: see table 2 > 15 0 C Grassland < 2% 10 68

69 Other 2-5% 5 > 5% 0 < 2% 2 > 2% Mineralization: see table 2 For all other soils (arable soil and other land use) it is assumed that net nitrogen mineralization may occur if soil organic matter content is higher than 2 percent. These are the soils that generally are cultivated. For this calculation, data on total C in the top soil (0-25 cm) is used. It is assumed that in soils with more than 10 percent organic (peaty soils) 100 kg N per ha per year is mineralized. This estimate is based on results of Hassink (1995), showing that more than 100 kg N per ha per year may be mineralized in drained peat soils in the Netherlands used for agriculture. It is assumed that in soils with low organic C contents (i.e. < 2% C in 0-25 cm layer), no nett mineralization occurs. For classes 2-5% total C and 5-10% total C, mineralization of 25 and 50 kg N per ha per year are assumed, for average annual temperature of 5 to 15 o C. For lower average temperatures, a lower mineralisation is assumed and for higher average temperature, a higher mineralization is assumed. In table 2 the mineralization in dependence on temperature and organic C contents are presented.. In the calculations with MITERRA-EUROPE, the net N mineralization is added to the soil N surplus. 69

70 Table 2. Nitrogen mineralization in non-grassland agricultural soils, in dependence of the content of total C in the 0-25 cm layer. Average annual Total C in 0-25 cm layer Nett mineralization, temperature kg N per ha per year < 5 0 C < 2% Accumulation: table % % 20 > 10% C < 2% Accumulation: table % % 50 > 10% 100 > 15 0 C < 2% Accumulation: table % % 100 > 10% 200 Leaching from stored manure Introduction Manure stored in the open air on soil (without a floor) is susceptible for leaching and surface run-off. In a study of Sommer and Dahl (1999) in Denmark nitrogen leaching losses were <0.4% of the initial N during composting (197 days) of deep litter from dairy cows housings in heaps. In a similar study, Sommer (2001) showed that most of the nitrogen loss during storage of solid deep litter from dairy cow houses was due to NH 3 volatilization. Leaching accounted for 2 to 3 percent of the initial N content. Only a little N was lost due to denitrification. A study of Dewes (1995) in Germany showed that 2.5 to 3.4 percent of initial amount of N in manure heaps leached to deeper soil layers during a period of 177 days. Ammonia losses were much higher (25-45 percent) in this study. Also a study of Eghball et al. (1997) in the USA pointed at low leaching losses during composting of cattle manure (i.e. total runoff of nitrate and ammonium < 0.5% of the initial N). These studies indicate that leaching during composting of manure in temporary manure heaps (storage time < 200 days) are low (i.e. < 4 percent of the initial N). High concentrations of nitrate (3000 mg N/litre), and ammonium (5000 mg/litre) were found in the unsaturated zone beneath a 20 year old turkey litter storage on chalk in the UK (Gooddy, 2002). Below the top 5 meters of the profile, concentrations declined dramatically. Measurements of soil water under a long-term unlined cattle slurry lagoon in the UK showed that constituents of slurry moved in 20 years up to more than 30 meters depth (Gooddy et al., 2002; Wither et al., 1998). Just below the storage, high ammonium concentrations were found (up to more than 750 mg per liter), but no nitrate could be detected. However, from about 8 m depth, nitrate concentration strongly increased (up to more than 750 mg per liter) and ammonium decreased. This suggest that the soil beneath the slurry storage is anaerobic, 70

71 whereas oxygen diffusion in deeper layers, creates aerobic conditions, stimulating nitrification (figure 4). Sutter et al. (2005) found high ammonium concentrations in the upper 3 meter of the soil below cattle and pig manure lagoons in USA. Nitrate concentrations were low, but results of deeper layers were not available. It is often assumed that the soil surface is sealed by slurry, which may decrease leaching losses. However, the results indicate that in long-term cattle and pig slurry lagoons, ammonium and nitrate concentrations in the soil solution can be very high. Culley and Phillips (1989) showed significant N leaching from long-term unlined (earthen) dairy manure storages in the USA. They indicated that total N recovery of unlined dairy manure storages was 43 percent. This means that 57% of the stored manure N was lost, probably both by ammonia volatilization, denitrification, and N leaching. Some rough estimates on bases of the paper of Ham and DeSutter (1999) suggest that about 5 percent of the stored ammonium in swine-waste lagoons in USA (Kansas) was lost via seepage. The results indicate that nitrogen concentration in the groundwater below permanent manure storages can reach high concentrations. Figure 4. Summary of physical and chemical processes beneath an unlined earth-banked slurry storage lagoon on the Upper Chalk at ADAS Bridgets (Gooddy et al., 1998). Calculation method For MITERRA-EUROPE, leaching fractions (i.e. percentage of stored N that is lost) for manure storage were estimated (table 3). These estimates were based on expert judgement, because there are only a few studies in literature in which leaching is expressed in percentage of the manure-n stored per year. Data on the distribution of the amounts of stored solid and liquid manures in countries are derived from RAINS. Also data on the percentage of covered manure storage in countries are derived from RAINS. Data for the presence of concrete floors in manure storages were estimated by Pietrzak. For the presence of concrete floors, the following assumptions are made: 71

72 o All countries: 90 percent of the storages have a concrete floor o Central and South Europe: 35% of solid manure storages have a concrete floor o North and West Europe: 50% % of solid manure have a concrete floorete floor Table 3. Leaching fractions for stored manure. Type of manure system Concrete floor Cover Leaching fraction, % of stored N Liquid/slurry no no 10 yes 5 yes no 0 yes 0 Solid no no 5 yes 2 yes no 2 yes 0 Surface run-off Introduction Schwaiger et al. ( ) carried out a desk study to quantatively assess the surface runoff of N from agricultural soils. The findings of this desk study are used to estimate leaching fractions for surface runoff in MITERRA-EUROPE. Surface runoff occurs when rainfall exceeds a soil's maximum saturation level. When the soil is saturated and the depression storage filled and rain continues to fall, the rainfall will immediately produce surface runoff. If the amount of water falling on the ground is greater than the infiltration rate of the surface, runoff or overland flow will occur. The rate of runoff flow depends on the ratio of rain intensity to the infiltration rate. If the infiltration rate is relatively low, such as when a soil is crusted or compacted, and the intensity is high, then the runoff rate will also be high. Runoff specifically refers to the water leaving an area of drainage and flowing across the land surface to points of lower elevation. Runoff involves the following events i) rainfall intensity exceeds the soil's infiltration rate and ii) a thin water layer forms that begins to move because of the influence of slope and gravity. Important factors controlling surface-runoff are the type, period and amount of N application, the slope of the soil, soil type and properties, weather conditions (precipitation, frost), and hydrology. In MITERRA-EUROPE, the leaching fraction for surface-runoff is expressed in percent of the N applied as fertilizer and manure. The major findings of Schwaiger et al. (2006) are Parameters for a high risk of nitrogen surface runoff are: o Weather conditions - heavy precipitation, snowmelt, storm o Soil conditions - soil with low infiltration rate 1 Elisabeth Schwaiger, Bettina Schwarzl & Gerhard Zethner (2006) Desk study of surface runoff from application of fertilisers and organic manure to soils. Umweltbundesamt, Austria 72

73 o N Fertilizer input - high amount of fertilizer o Kind of vegetation (growing season). Korsaeth & Wright (2000) experienced by comparing different land use methods that runoff can reach from kg N ha -1 year -1. Forage system had lower N runoff then arable systems. o Traditional (conventional) tillage. Dowdell et al. (1987) showed experimentally the effects of different tillage methods on clay soil. Soil tillage is the key management to avoid or perpetuate the runoff fraction not only the erosion particles. It is difficult to distinguish between N from leaching runoff and erosion. To separate the effects from different tillage methods data on tillage is needed. For Europe only estimations can be used to figure out the real situation. o Steep slope Beside the weather conditions the soil infiltration is of great importance preventing surface runoff. The soil infiltration depends on the soil texture (a sandy surface soil normally has a higher infiltration rate than a clayey surface soil), crust, compaction (an impervious layer close to the surface restricts the entry of water into the soil and tends to result in ponding on the surface), aggregation/structure, water content (the infiltration rate is generally higher when the soil is initially dry and decreases as the soil becomes wet), organic matter (organic matter increases the entry of water by protecting the soil aggregates from breaking down during the impact of raindrops) and pores (top soil air capacity). The surface runoff is also influence by the kind of field fruits (esp. at steep slopes ) and the soil management ( preference minimum tillage). There is no literature about nitrogen surface runoff from different kind of fertilizer application. In the literature we found no information about field trials on surface runoff and different kind of nitrogen fertilizer (manure, slurry, mineral fertilizer). The estimation of the nitrogen surface runoff from different fertilizer depends on several parameters. In general the assumption is that % of total nitrogen load in surface water is caused by surface runoff, the rest by leaching. If we assume that an adequate amount of fertilizer/manure is applied, the most important factors causing surface runoff are i) the amount of precipitation, ii) the slope and iii) the vegetation. Assumptions and calculation method Surface runoff fractions were estimated on basis of expert judgement. The surface-runoff fractions are expressed in percentage of the N applied via fertilizer and manure per year. The following factors were included in the estimate: o The slope o Precipitation o Soil type o Crop The N input is also included, because the surface runoff is calculated from the applied amounts of fertilizer and manure. 73

74 The suface runoff is calculated from a maximal surface runoff and a set of leaching factors. LF surface runoff = LF surface runoff, max * f lu * MIN (f p, f rc, f s ) In which o LF surface runoff = leaching fraction for runoff in % of the N applied via fertilizer and manure (including grazing) o LF surface runoff, max the maximum leaching fraction for different slope classes o f lu = reduction factor for land use or crop o f p = reduction factor for precipitation o f s = reduction factor for soil type o f rc = reduction factor for depth to rock The slope is an important factor controlling surface runoff. Moreover, in the Nitrate Directive measures are mentioned that specifically aim at reducing surface runoff from sloping soil. Therefore, in MITERRA-EUROPE slope is included as a factor affecting surface runoff. For four slope classes, a maximum surface runoff factors are set. Also in flat areas, surface runoff can occur during wet periods, and especially on heavy textured soils. The following slope classes and surface runoff factors are distinguished: o Level (dominant slope ranging from 0 to 8 %): LF surface runoff, max = 10 o Sloping (dominant slope ranging from 8 to 15 %): LF surface runoff, max = 20 o Moderately steep (dominant slope ranging from 15 to 25 %): LF surface runoff, max = 35 o Steep (dominant slope over 25 %): LF surface runoff, max = 50 It assumed that smallest surface runoff occurs in grasslands, because the grassland soil is covered the whole year by a crop. Moreover, soil tillage is an important factor that may enhance surface runoff. Permanent grassland soils are not tilled. It is assumed that surface runoff is four times lower in grassland than for other agricultural land use types: o For other land use: f lu = 1.00 o For grassland: f lu = 0.25 Surface runoff is dependent on rainfall. Largest runoff occur in periods with heavy rainfall in which soil are already wet. Thus, surface runoff occurs during events and this it is not possible to model such events in MITERRA-EUROPE which calculates losses on an annual basis. The precipitation surplus is chosen as an indicator of rainfall effect on surface runoff. It is assumed that surface runoff may also occur during wet conditions in dry regions (i.e. in regions with a low precipitation surplus). Reduction factors precipitation surplus: fp Precipitation surplus, mm fp >

75 < Soil type has a strong effect on surface runoff, i.e. risk on surface runoff increases when clay content of the soil increases. The following reduction factors f s are included: Very fine (clay > 60 %): f s = 1 Fine (35% < clay < 60%): f s = 0.90 Medium ( 18-35% clay): f s = 0.75 Coarse (18% < clay): 0.25 Peat: 0.25 The last factor that is included is the depth to rock, because surface runoff is highest in shallow soil. The surface runoff factors for depth to rock are: For a depth of less than 25 cm: frc = 1 For a depth of more than > 25 cm: frc = 0.8 Leaching below rooting zone Introduction The N surplus is the difference between the N input to soil via manures, fertilizer, atmospheric deposition, and biological fixation and the output via harvested crops. In MITERRA-EUROPE, the surplus is corrected for ammonia emission from manure and fertilizer, surface runoff, and mineralization or accumulation in soil organic matter. In MITERRA, the corrected N surplus is divided in denitrification and leaching using leaching or denitrification fraction: denitrification fraction (DF) + leaching fraction (LF) = 1). This is the leaching below the rooting zone or top soil (about the upper 1 meter of the soil profile) ; the fate of the nitrate below this layer is not accounted for in the model. This nitrate may be denitrified, leached to groundwater or leached to surface water. In order to derive denitrification or leaching fractions, insight is required in the processes controlling denitrification and leaching in soils and the ratio between these two losses. Factors controlling denitrification Denitrification is the microbial process in which nitrate is reduced to gaseous nitrogen compounds. The most important factors controlling denitrification are i) the presence of an energy source for the denitrifying bacteria, mostly available organic carbon, ii) anoxic conditions, and iii) the nitrate content in the soil. If any of these conditions is not fulfilled, denitrification is unlikely. Denitrification is a microbial process, and therefore trivial factors affecting biological processes, such as the temperature and ph, may also affect denitrification. Anoxic conditions. Denitrification is an anaerobic process. Factors that affect the oxygen concentration in the soil are the wetness of the soil and the biological oxygen consumption. The wetness of the soil is controlled by rainfall, irrigation, evaporation, transpiration, groundwater table, and water holding capacity of the soil. The biological oxygen consumption is affected by 75

76 microbial respiration of organic matter in the soil, such as crop residues and manure, and respiration of plant roots. In most agricultural top soils aerobic conditions will prevail, because farmers will try to keep the soils aerated in order to stimulate crop growth. In the top soil, O 2 abundantly occurs in general, thus does not allowing denitrification to proceed. Generally, denitrification rates in the top soil increase after rainfalls or irrigation and decrease again when the soil dries out. The chance on for anoxic conditions is higher in soils with low porosity (clayey and loamy soil) than in soils with a coarse soil structure, such as in sandy soils (Ruser et al., 2005). The O 2 -content is also affected by soil compaction, e.g. by tractors or grazing cattle. Soil compaction may enhance denitrification, especially in wet soils (Ruser et al., 2005). The presence of an energy source. Denitrifying bacteria generally use available organic carbon as energy source. In some soils (and especially the deeper anaerobic soil layers) other possible energy sources can be available, such as iron sulphide (pyrite). Organic C-sources are available in most agricultural top soils in the form of soil organic matter, decaying plant roots, crop residues, and manure. In permanent grasslands organic matter accumulates during ageing, whereas soil cultivation in arable land result in a strong degradation of organic matter and lower organic matter contents (figure 3). Potentials for denitrification are higher in grassland than in arable land (Munch and Velthof, 2006). A monitoring programme in the Netherlands indeed show that a larger part of the N surplus leaches in arable land than in grassland (see below and table 4). In arable soils, denitrification is higher when crop residues with easily available C are incorporated in the soil, such as leaves from sugar beet and vegetables, than when crop residues with stable organic C is incorporated, such as straw from wheat (Paul & Beauchamp, 1989b; Van Cleemput et al., 1990; McKenney et al., 1993; Velthof et al., 2002). Manures contain easily degradable C, such as volatile fatty acids, and application of manures to soils increases denitrification activity (Flessa et al, 2002; Paul and Beauchamp, 1989a; Velthof et al., 2005). The nitrate content in the soil There are many possible sources of nitrate in agricultural soils, including artificial fertilizers, manures, organic products, crop residues, atmospheric deposition, and biological N 2 - fixation. Nitrate can be directly applied to soils via artificial fertilizers. Application of ammonium containing fertilizers and manures may also increase the nitrate content of the soil by nitrification. Organic N can be mineralized into ammonium and, after nitrification, to nitrate in the soil. Thus, application of organic N via manures or crop residues may also increase the nitrate content in the soil. The nitrate content in agricultural soils strongly varies in time, because of the different sources and sinks of nitrate. Generally, highest nitrate contents in top soils are found just after application of nitrate fertilizer or manure application. In this period, risk on denitrification. Velthof et al, (1997) showed that denitrification losses from grassland during wet conditions were much higher after application of nitrate containing fertilizer than of manure and ammonium containing fertilizer. The nitrate content in the soil decreases in time after nitrogen application to soil, because of plant uptake, and thereby the risk on denitrification also decreases in time. Other factors Denitrification rates increase when the temperature increases. An increase in activity with a factor 2 when the temperature increases with 10 o C is common for biological processes. 76

77 Although denitrification strongly decreases with decreasing temperature, significant but low denitrification activity has been detected at temperature < 5 o C (e.g. Malhi et al., 1990). Denitrification activity increases with ph, with an optimum ph in the range of 7.0 to 8.0. Denitrification at ph 7 to 8 is about a factor 2 tot 3 higher than for ph less than 6 (Granli and Bøckman, 1994). Calculation method MITERRA-EUROPE calculates the fate of the N surplus on bases of soil and climatological conditions. The following approach is chosen to calculate leaching: Step 1. The maximum leaching fraction (LF soil type, max, in % of N surplus that leaches below rooting depth) is set per soil type, assuming that soil type is the major factor controlling the ratio between leaching and denitrification. Soil type (or texture) strongly affects oxygen concentration. Moreover, in peat soils high organic C contents and generally high groundwater tables created conditions favourable for denitrification. In general, denitrification losses will increase in the order: sandy soil < loamy soils < clay soils <peat soil (Barton et al., 1999; Koops et al., 1996; Van Beek et al., 2003). Step 2. The maximum leaching fraction is corrected for effects of land use (grassland versus arable land) using a reduction factor (f lu: ). Land use has a strong effect on available organic C contents in the soil and thereby on the ratio between leaching and denitrification. Step 3. The leaching fraction per combination of soil type and land use is corrected for different factors that affect denitrification and leaching in soil, i.e. Reduction factor for soil organic content content (fc), because denitrification potential increases with increasing organic C content. Part of this effect is already allowed for in land use, but differences in organic C content within arable sols and with grassland may also cause differences in denitrification. Reduction factor for precipitation surplus (fp). The precipitation surplus is in combination with soil texture an indicator for the wetness of the soil. However, precipitation in combination with soil texture is also an indicator for the risk on N leaching, i.e. the combination of a high precipitation surplus and a coarse textured soil create conditions with high succeptibility for leaching, but combination of a high precipitation surplus and a fine textured soil create conditions with high chance on denitrification. Reduction factor for temperature (ft). At the same conditions, denitrification will be lower and nitrate leaching higher in regions with low temperature than in regions with high temperature. Reduction factor for rooting depth (fr). The risk on N leaching below rooting zone increases when the rooting depth decreases. Studies clearly indicate that deeply rooting crops, can remove nitrate from the soil profile up to more than 1 meter (Kristensen & Thorup-Kristensen, 2004). In the model we only account for the factor that has the largest (estimated) effect on leaching, i.e. the minimum of the four reduction factors fp, fr, ft, and fc. 77

78 Thus, the leaching faction (LF, in % of the corrected N surplus) is calculated as: LF = LF soil type, max * flu * MIN (fp, fr, ft, fc). The corrected N surplus is defined as Total N input - total N output NH 3 emission soil N2O emission soil - surface runoff + nett N mineralization where total N input = N input via fertilizer, manure, grazing, atmospheric deposition, and biological N fixation total N output = N removed via harvested crop NH 3 emission soil = NH 3 emission from soil applied fertilizer, manure, and grazing N 2 O emission soil = N 2 O emission from soil applied fertilizer, manure, grazing, atmospheric deposition and biological N fixation surface runoff = surface runoff of fertilizer and manure nett N mineralization = mineralization accumulation of N Step 1 The maximal leaching fractions are derived from results of a national monitoring network in the Netherlands, in which both the nitrogen surplus and the nitrate concentration in the upper ground water for sandy soils and drainage and ditch water for clay and peat soils were determined. According to the measurements collected in the Monitoring Program 39% of the N surplus of grassland on sandy soils leaches to the groundwater (Schröder et al., 2005 & 2006; table 4). This is in agreement with results of Wachendorf et al. (2004) who found a leaching fraction of 30-40% on a similar soil type. Much higher leaching fractions are indicated by the Monitoring Program for arable land, up to 100 percent for dry sandy soils. These results suggest that in arable land on dry sandy soils, denitrification losses are negligible and that the total N surplus leaches below the rooting depth. The observed nitrate- N concentrations are lower, the higher the groundwater level. This reduction of concentration ranges from 0% on sandy soils with deep groundwater (mean highest groundwater table during winter (MHG) > 0.80 meter deep) to 57% on sandy soils with shallow groundwater (MHG < 0.40 meter deep). These figures are based on research carried out in the years on field level (Van der Meer, 1991) on farm level (Boumans et al., 1989; Breeuwsma et al., 1991), as well as on experiments with lysimeters (Steenvoorden, 1988). 78

79 Table 4. Net leaching fractions (kg N leached per kg soil N surplus; s.d. s based on yearly variation in brackets), as affected by land use and mean highest groundwater level (MHG) (Schröder et al., 2005& 2006 using data of the Dutch National monitoring programme). Soil type Net leaching Ratio leaching fraction, kg/kg fraction arable Arable land Grassland land/grassland Sand, MHG < 0.40 meter 0.50 (0.08) 0.18 (0.04) 0.36 Sand, 0.80 < MHG < 0.40 meter 0.75 (0.09) 0.28 (0.05) 0.37 Sand, MHG > 0.80 meter 1.06 (0.08) 0.39 (0.06) 0.37 Clay 0.31 (0.06) 0.11 (0.05) 0.35 Peat 0.04 (0.01) Average 0.36 These are leaching fractions based on the environmental conditions in the Netherlands. In the used modeling approach only reduction functions are used, which means that leaching fractions are equal or less than the maximum leaching fraction. For loam, sand, and peat maximum leaching fraction is less than 1. The question is whether there are conditions in other countries by which maximum leaching fraction of loam, peat, and clay are higher than those in the Netherlands or whether there conditions which are less favourable for denitrification than in the Netherlands. The following conditions may play a role: Temperature. The average annual temperature in the Netherlands is 9 o C. Denitrification is dependent on temperature and denitrification losses are smaller under cold conditions. Wetness. A relatively high precipitation surplus (>300 mm per year) and high groundwater levels create conditions favorouble for denitrification in clay and peat soils. It may be expected that under drier conditions, less N is denitrified and more N is leached. Soil organic C. Soil in the Netherlands are relatively rich in C, in comparison to soils elsewhere in Europe. Denitrification losses are smaller in soils with low soil organic C contents. Thus, leaching fractions are higher in soils with low C contents than in soils with high C contents. Concluding, there are several factors indicating that the maximum leaching fractions for loam, clay and peat soils can be higher than those experimentally found in the Netherlands. However, because it is well-known that denitrification is higher in clay and peat soils, it is assumed that maximum leaching fractions are smaller than 1. In MITERRA-EUROPE the following maximum leaching fractions are used: Maximum leaching fraction on sandy soil (LFsand, max) = 1 Maximum leaching fraction on loamy soil (LFloam, max) = 0.75 Maximum leaching fraction on clay soil (LFclay, max) = 0.50 Maximum leaching fraction on peat soil (LFpeat, max) =

80 Step 2 As indicated in table 4, the leaching fraction for grassland is on average 0.36 times the leaching fraction of arable land, for all soil types. Thus, the reduction factor for land use (f lu ) is: o For other land use: f lu = 1.00 o For grassland: f lu = 0.36 o Step 3 The reduction factor for the precipitation surplus (fp) is dependent on soil type. It is assumed that leaching on sandy and loamy soils is highest when precipitation surplus is highest. However, it is assumed that a high precipitation surplus on peat and clay results is anaerobic soil conditions and higher denitrification. For all soils, a small leaching fraction is assumed at low (or negative) precipitation surplus, because in dry regions with low precipitation surplus leaching may accur during heavy rainfall events. In table the reduction factors for precipitation used in MITERRA-EUROPE are presented. Reduction factor for precipitation surplus: fp Precipitation surplus, mm fp sand en loam fp peat en clay > < Soils with a very shallow rooting depth are more succeptible for leaching than soil with a deep rooting depth. In the Netherlands the average rooting depth is about 90 cm depth. The maximum leaching fraction is based on results from the Netherlands Obstacle to roots between 20 and 40 cm depth Rooting depth < 40 cm: fr = 1 Rooting depth > 60 cm: fr = 0.75 Denitrification increases with increasing temperature. In MITERRA-EUROPE, the following leaching fractions are used, assuming the denitrification at 15 o C is twice of that at 5 o C (a general effect of temperature on microbial activity): < 5 o C: ft = o C: ft = 0.75 > 15 o C: ft = 0.50 It is assumed that the denitrification decreases (and leaching fraction increases) when total C content of the soil decreases. The reduction factors for total C (ft) are: < 1% ft = 1 1-2% ft = % ft =

81 > 5% ft = 0.50 References Barton, L., McLay, C.D.A., Schipper, L.A. and Smith, C.T., Annual denitrification rates in agricultural and forest soils: a review. Australian Journal of Soil Research. 37: p Boumans, L.J.M., C.R. Meinardi & G.J.W. Krajenbrink, Nitraatgehalten en kwaliteit van het grondwater onder grasland in de zandgebieden. Rapport , RIVM, Bilthoven, 43 pp. Breeuwsma, A., J.P. Chardon, J.F. Kracht & W. de Vries, Pedotransfer functions for denitrification. In: Soil and groundwater research report II: Nitrate in soils. Directorate General Science, Research and Development, EUR 13501, Culley, JLB & Phillips, PA (1989) Retention and loss of nitrogen and solids from unlined earthen manure storages. Transactions-of-the-ASAE. 32: Cuttle, S.P. & D. Scholefield (1995) Management options to limit nitrate leaching from grassland. Journal of Contaminant Hydrology 20, De Sutter, T.M., G.M. Pierzynski, and J.M. Ham (2005) Movement of lagoon-liquor constituents below four animal-waste lagoons. Journal of Environmental Quality 34, Dewes,T (1995) Nitrogen losses from manure heaps. P In: Kristensen et al. (eds.) Nitrogen leaching in ecological agriculture. Proceedings of an International Workshop, Royal Veterinary and Agricultural University, Copenhagen, Denmark.; AB Academic Publishers,. Bicester, UK. Eghball,B, Power, JF, Gilley, JE and Doran JW (1997) Nutrient, carbon, and mass loss during composting of beef cattle feedlot manure. Journal of Environmental Quality 26,: Flessa H., Ruser, R., Schilling, R., Loftfield, N., Munch, J.C., Kaiser, E.A. and Beese F. (2002) N2O and CH4 fluxes in potato fields: automated measurement, management effects and temporal variation. Geoderma 105: Gooddy, DC (2002) Movement of leachate from beneath turkey litter sited over chalk in Southern England. Journal of Environmental Science and Health Part B. Pesticides, Food Contaminants, and Agricultural Wastes. 2002; 37(1): Gooddy, D. C., Withers, P.J. A., McDonald, H. G., and Chilton, P. J. (1998) Behaviour and impact of cow slurry beneath a storage lagoon: II. Chemical composition of chalk porewater after 18 years. Water, Air, Soil Pollut, 107:

82 Granli, T. and Bøckman, O.C., Nitrous oxide from agriculture. Norwegian Journal od Agricultural Sciences, Supplement 12, 128 pp. Ham, JM and DeSutte TM (1999) Seepage losses and nitrogen export from swine-waste lagoons: a water balance study. Journal of Environmental Quality. 28: Hassink, J. (1994) Effects of soil texture and grassland management on soil organic C and N and rates of C and N mineralization. Soil Biology and Biochemistry 26, Hassink, J Organic matter dynamics and N mineralization in grassland soils. Proefschrift Landbouwuniversiteit Wageningen, 250 p. Heathwaite A.L The effect of drainge on nutrient release from fen peat and its implications for surface water quality a laboratory simulation. Water, Air and Soil Pollution 49: Hoogerkamp, M. (1984) Changes in productivity of grassland with ageing. Doctoral thesis, Agricultural University Wageningen, 78 p. Jenkinson, D.S. (1988) Soil organic matter and its dynamics, p In: Wild, A. (ed.) Russels s Soil Conditions and Plant Growth. 11th edition, Longman, New York. Johnston, A.E., Soil organic matter, effects on soils and crops. Soil Use & Management 2: Korsaeth, A. & Eltun, R. (2000): Nitrogen mass balances in conventional, integrated and ecological cropping systems and the relationship between balance calculations and nitrogen runoff in an 8-year field experiment in Norway, Agriculture, Ecosystem & Environment Volume 79, Koops, JG, O Oenema & ML van Beusichem (1996) Denitrification in the top and sub soil of grassland on peat soils. Plant and Soil 184, Kristensen, HL & Thorup-Kristensen, K Root growth and nitrate uptake of three different catch crops in deep soil layers. Soil Science Society of America Journal, 68, Malhi, SS, WB Mc Gill, & M. Nyborg (1990) Nitrate losses in soils: effect of temperature, moisture and substrate concentration. Soil Biology and Biochemistry 22, McKenney, DJ, SW Wang, CF Drury & WI Findlay (1993) Denitrification and mineralization in soil amended with legume, grass, and corn residues. Soil Science Society American Journal 57: Munch, JM & GL. Velthof (2006) Paragraph 5b. denitrification and agriculture. In: H. Bothe, S.F. Ferguson & W.E. Newton (eds.) Biology of the Nitrogen Cycle. Elsevier (in press.) 82

83 Paul JW & Beauchamp EG 1989a Effect of carbon constituents in manure on denitrification in soil. Canadian Journal of Soil Science 69: Paul, JW & EG Beauchamp (1989b) Denitrification and fermentation in plant-residueamended soil. Biol Fert Soils 7: Ruser, R., Flessa, A., Russow, R., Schmidt, G., Buegger, F. and Munch, J.C. (2005) Emissions of N2O, N2 and CO2 from soil fertilized with nitrate: effect of compaction, soil moisture and rewetting. Soil Biology and Biochemistry (in press). Schothorst, C.J Subsidence of low moor peat soils in the western Netherlands. Geoderma 17: Sommer SG (2001) Effect of composting on nutrient loss and nitrogen availability of cattle deep litter. European Journal of Agronomy : Schröder, J.J., H.F.M. Aarts, J.C. van Middelkoop, M.H.A. de Haan, R.L.M. Schils, G.L. Velthof, B. Fraters & W.J. Willems, Limits to the use of manure and mineral fertilizer in grass and silage maize production, with special reference to the EU Nitrates Directive. Report 93, Plant Research International, Wageningen, 48 pp. Schröder J.J., H.F.M. Aarts, J.C. van Middelkoop, G.L. Velthof, B. Fraters & W.J. Willems (2006) Limits to the use of manure and mineral fertilizer in grass and silage maize production on sandy soils in The Netherlands. Submitted to European Journal of Agronomy. Sommer, SG and Dahl, P (1999) Nutrient and carbon balance during the composting of deep litter. Journal of Agricultural Engineering Research 74: Steenvoorden, J.H.A.M., Vermindering van stikstofverliezen naar grond- en oppervlaktewater. Nota 1849, ICW, Wageningen, 27 pp. Tyson, K.C., D.H. Roberts, C.R. Clement & E.A. Garwood (1990) Comparison of crop yields and soil conditions during 30 years under annual tillage or grazed pasture. Journal of Agricultural Science 115, Van Beek CL, Hummelink EWJ, Velthof GL & Oenema O (2003) Nitrogen losses through denitrification from an intensively managed grassland on peat soil. Biology and Fertility of Soils 39(4), in press. Van Cleemput, O, RM Malkanti, Y d Ydewalle & L Baert (1990) Denitrification influenced by incorporated harvest residues. Mitteilungen der Deutschen Bodenkundlichen Gesellschaft 60: Van der Meer, H.G., Stikstofbenutting en -verliezen van gras- en maïsland. Onderzoek inzake de mest- en ammoniakproblematiek in de veehouderij. Rapport nr. 10. DLO, Wageningen. 134 pp. 83

84 Van Drecht, G., A.F. Bouwman, J.M. Knoop, A.H.W. Beusen, and C.R. Meinardi (2003) Global modeling of the fate of nitrogen from point to nonpoint sources in soil, groundwater, and surface water. Global Biogeochemical cycles, 17, No.4, 115, Vries, W. de, J. Kros, O. Oenema and J. de Klein (2003) Uncertainties in the fate of nitrogen II: A quantitative uncertainties in major nitrogen fluxes in the Netherlands. Nutrient Cycling in Agroecosystems 66: , Velthof G.L., O. Oenema, R. Postma and M.L. van Beusichem (1997) Effects of type and amount of applied nitrogen fertilizer on nitrous oxide fluxes from intensively managed grassland.nutrient Cycling in Agroecosystems 46: Velthof, G.L. & O. Oenema (2001) Effects of ageing and cultivation of grassland on soil nitrogen. Report 399, Alterra, Wageningen, 55 p. Velthof, G.L., P.J. Kuikman & O. Oenema (2002) Nitrous oxide emission from soils amended with crop residues. Nutrient Cycling in Agroecosystems 62, Velthof, G.L., Nelemans, J.A., Oenema, O. & Kuikman, P.J. (2005) Gaseous N and carbon losses from pig manure derived from different diets. Journal of Environmental Quality 34, Vertes, F., Hatch, D.J., G.L. Velthof, Abiven, S, A. Hopkins, G. Springob (2004). Effects of grassland cultivation on N and C cycles and soil quality dynamics. Grassland Science in Europe Volume 9, Wachendorf, M., M. Büchter, H. Trott & F. Taube, Performance and environmental effects of forage production on sandy soils. II. Impact of defoliation system and nitrogen input on nitrate leaching losses. Grass and Forage Science 59, Whitehead, D.C., A.W. Bristow and D.R. Lockyer (1990). Organic matter and nitrogen in the unharvested fractions of grass swards in relation to the potential for nitrate leaching after ploughing. Plant and Soil 123: Withers, P.J. A., McDonald, H. G., Smith, K. A., and Chumbley, C. G. Behaviour and impact of cow slurry beneath a storage lagoon (1998): I. Groundwater contamination Water, Air, Soil Pollut., 107:

85 Annex 4. Desk study of surface runoff from application of fertilisers and organic manure to soils Elisabeth Schwaiger, Bettina Schwarzl, Gerhard Zethner Task - Aim of the study The issue of the study deals with question to what extend N is lost from agricultural areas in the surface water and semi natural areas via surface runoff into the surface water. Application of fertilizer and manures (including grazing) during wet condition to sloping soils can result in surface run-off to surface waters. Fertilizer include all mineral fertilizer and manure include all type of manures (solid manure, slurry, liquid manure, and urine and dung excreted during grazing). Important factors controlling surface-runoff are Type, period and amount of N application soil type and soil management weather conditions; precipitation, frost vegetation soil infiltration capacity (infiltration rate) Slope of the soil Miterra-Europe: In MITERRA-Europe the surface runoff of nitrogen applied to soil via fertiliser and manure has to be estimated, using data of slope, soil type and N application. In MITERRA-EUROPE, the leaching fraction for surface-runoff should be expressed in percent of the N applied as fertilizer and manure. This study is a literature review of surface runoff leaching fractions of N from mineral fertilizer, animal manure and slurry to surface waters as a function of soil type, slope and rainfall Definition - Surface runoff Surface runoff occurs when rainfall exceeds a soil's maximum saturation level. When the soil is saturated and the depression storage filled and rain continues to fall, the rainfall will immediately produce surface runoff. If the amount of water falling on the ground is greater than the infiltration rate of the surface, runoff or overland flow will occur. The rate of runoff flow depends on the 85

86 ratio of rain intensity to the infiltration rate. If the infiltration rate is relatively low, such as when a soil is crusted or compacted, and the intensity is high, then the runoff rate will also be high. Runoff specifically refers to the water leaving an area of drainage and flowing across the land surface to points of lower elevation. Runoff involves the following events: Rainfall intensity exceeds the soil's infiltration rate. A thin water layer forms that begins to move because of the influence of slope and gravity. On a global scale, runoff occurs because of the imbalance between evaporation and precipitation over the Earth's land and ocean surfaces. The distribution of runoff per continent shows some interesting patterns (see Table 1). Areas having the most runoff are those with high rates of precipitation and low rates of evaporation. Table 1 : Continental runoff values. (Lvovitch, M.L. 1972). Continent Runoff Per Unit Area (mm per yr.) Europe 300 Asia 286 Africa 139 North and Central America 265 South America 445 Australia, New Zealand and New Guinea 218 Antarctica and Greenland 164 Approach The following methods were used for the desk study: Literature study (scientific literature or reports, search on internet) Calculations of surface run off with models Colleagues, expert knowledge (risk assessment). Results from literature study Factors controlling surface-runoff Soil type soil management It is of no hard fact that the soil type has a strong influence. Maybe the influence expressed indirectly by the different kind of infiltration behaviour reduced permeability of soil increases the surface runoff. Schmid et al. (2001) found that extensive tillage like direct drilling or mulch drilling reduces soil erosion and surface run off (surface run off direct drilling: 3,2 l/m 2, mulch drilling: 12,2 l/m 2, conventional drilling: 21,2 l/m 2 ). Infiltration 86

87 Infiltration is the process by which water on the ground surface enters the soil. The rate of infiltration is affected by soil characteristics including ease of entry, storage capacity, and transmission rate through the soil. The soil texture and structure, vegetation types and cover, water content of the soil, soil temperature, and rainfall intensity all play a role in dictating infiltration rate and capacity. For example, coarse-grained sandy soils have large spaces between each grain and allow water to infiltrate quickly. Vegetation creates more porous soils by both protecting the soil from pounding rainfall, which can close natural gaps between soil particles, and loosening soil through root action. This is why forested areas have the highest infiltration rates of any vegetative types. For the rivers in Germany the surface runoff leaching was calculated for consolidated rock and unconsolidated rock according to hydro geological conditions (Werner & Wodsack, 1994). The percentage of surface runoff in unconsolidated areas is calculated as about 10 % of the total catchment runoff (= water quantity of surface runoff). This surface runoff is multiplied with a mean N-concentration of 0,32 mg N/l (=water quality of surface runoff). For areas with consolidated rock the mean concentration in rain is estimated as 2,45 mg N/l. In addition to that concentration the dissolved nitrogen from soil nitrogen content of the upper 3mm is assessed as 0,05% N of the total nitrogen content in soil per each erosive heavy rainfall. That is for the investigated districts in Germany about 0,027 kg N/ha (7 erosive heavy rainfalls assumed per year). For the former DDR a percentage of 3 % of regular applied nitrogen in manure is estimated to get lost via surface runoff. An average of 5,3% of the total diffuse N losses into surface waters is lost via surface runoff, 8,9 % in unconsolidated areas and 2,9 % in consolidated areas. In California rainfall simulation experiments were conducted on annual grassland and coastal sage scrub hillslopes to determine the quantities of C and N removed by surface runoff in sediment and solution. Undisturbed coastal sage scrub soils have very high infiltration capacities (> 140 mm h -1 ), preventing the generation of surface runoff. Trampling disturbance to the sage scrub plots dramatically reduced infiltration capacities, increasing the potential for surface runoff and associated nutrient loss. Infiltration capacities in the grassland plots (30-50 mm h -1 ) were lower than in the sage scrub plots. Loss rates of dissolved C and N in surface runoff from grasslands were 0.5 and mg m -2 s -1 respectively, with organic N accounting for more than 50% of the dissolved N. Trampling disturbance to the sage scrub plots dramatically reduced infiltration capacities, increasing the potential for surface runoff and associated nutrient loss. Infiltration capacities in the grassland plots (30-50 mm h -1 ) were lower than in the sage scrub plots. Loss rates of dissolved C and N in surface runoff from grasslands were 0.5 and mg m -2 s -1 respectively, with organic N accounting for more than 50% of the dissolved N. Total dissolved losses with simulated rainfall were higher than losses in simulations with just surface runoff, demonstrating the importance of raindrop impact in transferring solutes into the flow. Experimental data were incorporated into a numerical model of runoff and sediment transport to estimate hillslope-scale sediment-bound nutrient losses from grasslands. According to the model results, sediment-bound nutrient losses are 87

88 sensitive to the density of vegetation cover and rainfall intensity (Fierer & Gabet, 2002 ) Precipitation The amount of precipitation has a strong influence on the amount of water runoff and with this with the amount of nitrogen leached through runoff. Accountable are the effects of evapotranspiration that lower the runoff possibilities. In south Germany in a long term trial the effect of agricultural and non agricultural management practices on surface runoff and erosion at arable land (with a slope of >= 5 %) was observed. On the average the amount of surface runoff is about 3 % of the annual precipitation (the maximum is 10% at high rainfall intensity). It was also shown that, heavy rainfall (100 mm/26h) leads to a high surface runoff (50% of the water went to surface run off) but not evidently to high erosion. Erosion depends also on the kind of the field crops. The erosion on the potato field was 80 times higher than on winter barley. ( Vegetation Important factors of influence are the plant cover crops and average days without plant cover. Prasuhn et al. (2003) showed for the region Birs (Switzerland) with the model MODIFFUS the result that more then half of the amount of N-particulate input is lost via surface runoff leaching (see table 2). Table 2: Compilation of results of calculations with MODIFFUS: Surface runoff leaching and Erosion of different land use types (Prasuhn et al., 2003) Land use type t N year-1 N-Surface runoff leaching 23 Forest 0 N- leaching from agricultural land 21 Grassland 15 Permanent meadows 8 Meadows nearby housing 1 Alpine meadows 4 Orchards 0 Arable land 6 Vineyards 0 Horticulture 0 Unproductive areas 0 Road and streets 2 N-Particulate input (erosion and direct 33 input) Erosion arable land 5 Erosion vineyards 0 88

89 Erosion horticulture 0 Other erosion 19 Other direct input 9 EPA (2006) has shown the effects of different crop systems. About 10% of the N load to surface water is dissolved even by doing everything to avoid nitrogen surface leaching. Wu & Babcock (1997) calculated a runoff for 110 counties depending on the distribution of crop, irrigation system and the rotation practice from 0 to 12.1 kg N ha -1 with an average of 3.14 kg N ha -1. Heavy influence has the extension of corn cropping and irrigation usage. Korsaeth & Wright (2000) experienced by comparing different land use methods that runoff can reach from kg N ha -1 per year. Forage system had lower N runoff then arable systems. Mass balances fit best in the situation with mainly arable crops. Sources of N on the soil surface The content of nitrogen in soils nearby the soil surface has different input pathways. The soil itself contains a soil typical amount of nitrogen heavily influenced by climate, vegetation, clay content as well as fertilisation and soil tillage in cultivated soils. Incorporation of crop residues and biological nitrogen fixation make sure, that declining in nitrogen content will be limited. Most of the nitrogen content in soil is organically bund (mostly more than 95%) within humid substances, crop residues, biomass and dead organisms. Most of the inorganically bound nitrogen (available for plant nutrition) is available in form of nitrate (NO 3 - ) and only a small amount is available as ammonium (NH 4 + ) (Scheffer & Schachtschabel, 1992). Ammonia deposition via air and occult deposition has a mean importance in areas with high density of animal house keeping. Manure and slurry application on agricultural land leads to a high amount of nitrogen in soil, also leachable ammonia and nitrate. For fertilising crops and grassland also mineral fertilisers are used. In most cases the form of mineral nitrogen is half and half ammonia and nitrate. A special case is the use of urea it raises the content of ammonia in the soil. In general the overall effect of denitrification of nitrate to elementary nitrogen is depending on water content and compaction of the soil (anaerobic conditions) more or less high at the soil surface. That should lead to a moderate amount of nitrogen leaching. NH3 depositions on soil surface In regions with high density of animal husbandry the air deposition of NH 3 is very high. HAO et al. (2005) show mean values about 20 kg N ha -1 year -1 with a range of 5 to 84 kg N ha -1 year -1 with soil as basic substrate. The findings depend strongly on the upwind/downwind situation and the distance to the stables. Prasuhn & Mohni (2003) realise the sum of deposition (dry & wet, gaseous) about 5.0 to kg N ha-1 y-1 respectively. This fits with former calculations for Switzerland on open landscape, where 17.7 kg N ha -1 y -1 were found for deposition. 89

90 Deposition of ammonia on soil surface seems to be of high importance in areas with high density of livestock. For one year about 20 kg N ha -1 year -1 is a good estimation for that factor. Drilling of agricultural soil Autumn sowed crops reduce the danger to loose nitrogen through nitrate leaching. Dowdell et al. (1987) showed experimentally the effects of different tillage methods on clay soil. Drilling after ploughing versus direct drilling shows remarkable loss differences ranged from 3 to 75 kg N ha -1 year -1 and in average 34 kg N ha -1 year -1, via surface runoff 6 and 4 kg N ha -1 year -1. Soil tillage is the key management to avoid or perpetuate the runoff fraction not only the erosion particles. It is difficult to distinguish between N from leaching runoff and erosion. It helps a lot to decide between dissolved and particulate N. To separate the effects from different tillage methods data on tillage is needed. For Europe only estimations can be used to figure out the real situation. N load from slurry and manure No information about the different nitrogen surface runoff situation with manure or slurry use on agricultural land could be found. In our view no big difference can be estimated. N load from mineral fertilisers No further information by using mineral fertiliser on agricultural could be found. In our view such difference could be evident. Denitrification of N- in soil The denitrification of nitrogen molecules has most effects in the context of leaching through the soil horizon and has much lower effects on runoff leaching. Prasuhn & Spiess (2004) show some evident for such different effects depending on the type of soil. In table 4 it is shown which correction should be done when calculating the groundwater leaching fraction. Table 3: Denitrification factors (Prasuhn & Spiess, 2004): Denitrification factor Drained land Undrained land Soil type (FAL 1998) Peat, Peat land (Moor, Anmoor) M, N Calcic Flavisol, Dy. Flavisol (Fahlgley, Auboden) G, A Dy., Eu. Planosol (Pseudogley, Buntgley) I, W Gleyic Luvisol (Braunerde-Pseudogley, Braunerde-Gley) Y, V Regosol, Fluvisol, Rendzina, Calcic Luvisol (Kalkbraunerde), O, F, R, K O. Luvisol (Braunerde, Parabraunerde), 90

91 Cambisol (saure Braunerde) B, T, E N-surface runoff leaching fraction The dissolved nitrogen amounts in surface runoff are the result of the nitrogen amounts already dissolved in precipitation and of the leaching from soil nitrogen content. Prasuhn et al. (2004) calculate (model: MODIFFUS) a mean surface runoff concentration of nitrogen depending on the concentration in rain and for different landuse types. Table 4: N-Concentration of surface runoff, depending on N-concentration in rain and different land use types (Prasuhn et al., 2004) Land use categories Mean value (mg N/l) Vegetation free area Concentration in rain*1.1 Forest Concentration in rain*1.1 Unproductive vegetation Concentration in rain*1.1 Street & road offroad Concentration in rain*1.1 Alpine agricultural areas Concentration in rain*1.2 Extensive meadows and pastures Concentration in rain*1.2 Low intensive meadows 0.80 Permanent meadows 1.60 Pastures nearby housing 1.60 Orchards 1.60 Artificial meadows 1.60 Open arable land 1.60 Vineyards 1.60 Horticulture 1.60 For a specific catchment this concentration in rain will then be corrected by Nitrogen load (mg/l) * Precipitation factor * Manure factor * Grassland intensity factor * Arable land intensity factor = N-concentration (mg/l) Precipitation factor: Unfertilised areas (wood, extensive grassland alpine meadows unproductive areas streets and road vegetation free area) are only calculated as the rain concentration. The other areas are calculated with the region s typical concentration and weighted with 0.4. Manure factor The risk of nitrogen loss is strongly depending on increasing manure amount in the region - applied only on permanent meadows, pastures nearby housing, orchards and artificial meadows. Factors range from 0.7 to 1.3 respectively. Grassland intensity factor 91

92 Distinction between extensive and intensive used grassland per community was applied and weighted. Arable land intensity factor The potentially leaching of nitrogen from arable land is more often caused by erosion than in other land use. Artificial meadows are in this case the main focus. N-concentration The concentration ranges from 0.2 to 2.57 mg N/l respectively. The highest values arise in orchards and pastures nearby housing. The mean values of precipitation concentration was about 0.18 and 0.9 mg N/l respectively without the load of runoff leachate. Elevation factor, soil type, variable precipitation/evaporation was calculated in the model at a very early stage and it seems like it is a good estimation to come to a national wide result. Prasuhn (2003) shows also a development of the N-leaching through different paths between 1985, 1996 and 2001 in table 5. Table 5: Nitrogen loss by different ways of leaching and deposition 1985, 1996, 2001 in t year -1 Nitrogen loss (t y-1) Surface leaching Leaching 15,408 14,411 13,445 Drainage 2,628 2,464 2,229 Erosion Deposition Others Sum 19,219 17,902 16,610 The results show that for Switzerland the amount of surface runoff is much the same as for erosion. Prasuhn & Spiess (2004) have shown in some other areas surface runoff leaching of about 4.5 t N y -1 and for erosion about 13.5 t N y -1 respectively. Summarising the model results show that there is almost the same amount of N in erosion than in runoff leaching, if the landscape is varied. For the most European flat regions the amount of N in runoff is about 2 to 20 kg N ha 1 y -1. Based on a computer aided model Prasuhn and Braun (1994) made an estimation of surface runoff (and other water fluxes) in the Canton of Bern/Switzerland. By multiplication of water fluxes with the respective land-use specific and area specific matter concentrations, the different matter fluxes were then calculated. The results of the model calculation for the diffuse sources were compared to the values obtained for point sources. Surface runoff in Switzerland not only occurs from heavy rainfall but also from snow melt. 92

93 Beside precipitation and potential runoff (precipitation minus evapotranspiration) respectively, land cover, slope and soil conditions (infiltration) play an important role. For grassland as well as for arable land it was assumed that surface runoff occurs only at steep slopes. As only few literature is available it is suggested that the surface runoff of grassland is between 1,5-3,0 % from precipitation. In dependence on erosion it was assumed that on arable land on soft slopes the surface runoff is 1,5-3,0 % of precipitation (4% of potential flow resp.), on moderately steep slopes 2-4 % of precipitation (6% potential flow resp.) and on very steep slopes even more (3-5% of precipitation ~8% pot. flow). Snowmelt leads to a surface runoff of about 3 % of precipitation on unproductive vegetation. The following table shows the literature on surface runoff. The data are derived from long term field trials. Surface runoff % of precipitation Land use Region Literature source 1,5 Natural grassland Sempacher See/CH Braun et al ,5 Artificial Berner Braun &Leuenberger grassland Mittelland/CH ,0 Artificial Sempacher See Braun et al grassland 0,7 Fallow without vegetation cover (v.c) /CH Basler Tafeljura/CH Prasuhn ,1 Fallow without Basler Prasuhn 1991 v.c. Tafeljura/CH 1,9 Fallow without Möhlinger Feld Schaub 1989 v.c. /CH 2,5 Fallow without Napf/CH Rohrer 1985 v.c. 2,9 Fallow without Möhlinger Feld Schaub 1989 v.c. 3,7 Fallow without Napf /CH Rohrer 1985 v.c. 2,0 Arable land Berner Mittelland Braun &Leuenberger ,6 Arable land Mittelgebirge /Germany Preuss 1977 In Prasuhn and Mohni (2003) a model based calculation with GIS application was conducted in the Canton Bern. The parameters of the estimations were land use, potential flow (precipitation minus evapotranspiration), soil conditions and slope. It was assumed that: hills with less than 3% slope show no surface runoff. for grassland as well as for arable land the surface runoff is 7 % of the potential flow 93

94 for unproductive vegetation 4% of potential flow leads to surface runoff, In wood above 1200 m sea level the surface runoff is 2% of the potential flow. During avulsion nutrients are primarily bound to soil particles and secondarily to the soil surface. Thus Braun et al. (1991) found that the amount of soluble nutrients in surface runoff on arable land is less than on grassland. Summary of literature review: There is no literature about Nitrogen surface runoff from different kind of fertilizer application. In the literature we found no information about field trials on surface runoff and different kind of nitrogen fertilizer (manure, slurry, mineral fertilizer). There are few data about model results with an overall fertiliser input. Most of the models are calculating of N surface for catchments/regions. But these calculations do not consider the kind of applied manure or fertilizer and the different behaviour of manure, slurry, mineral fertilizer in surface runoff. Prasuhn indicates to correct the certain catchment with a manure correction factor referring to the standardised catchment. It seems to be a good approach to calculate N runoff through the single N concentration of precipitation and corrected with the land use factors shown by Prasuhn et al. In this light soil type and inclination have not such a direct influence as estimated. Another way to calculate the surface runoff is to multiply the water flux with the respective land use, slope and soil specific factors. The amount of N applied via fertilizer/manure (max. surface runoff) will then be adjusted by these specific factors. 94

95 Results from model review Surface runoff calculation in: NL- CAT The model chain NL-CAT (Nutrient Losses at catchment scale) (Schoumans et al.,2005) consists of the two important STONE components SWAP and ANIMO in combination with a surface water quantity and a surface water quality module. The SWAP module (Kroes and Van Dam, 2004) is used to generate hydrological input to the ANIMO module (Groenendijk et al., 2005) ANIMO simulates the nutrient cycle in soil and the nutrient leaching to groundwater and surface waters. Surface water discharges are simulated by the SURFACE WATER module (Smit et al., 2005). Finally, simulation of surface water quality processes and retention within a (large) catchment is performed by the NUSWALITE module (Siderius et al., 2005). To quantify the amounts of P (and optionally N) added to the surface water system via surface erosion, the NL-CAT model has been extended with a simple erosion module; P-USLE. This module is based on the modified and revised Universal Soil Loss Equations (USLE) and implemented in a GIS-environment (Walvoort, 2004). Figure 1 shows the interrelations between the various modules in NL-CAT. Discretisation module SWAP Hydrological module PUSLE Erosion ANIMO Soil and groundwater quality module SWQN Hydraulic module NuswaLite Surface water quality Model output Figure 1 Model components of the quantification tool NL-CAT 95

96 The waterflow towards adjacent fields and surface water elements caused by surface runoff (overland flow) depends on: - infiltration capacity of the upper soil layers - saturation degree of the soil. Prevailing rainfall and snow melt on a saturated soil can not be stored within the soil, but stay within a ponding layer and when the maximum ponding thickness is exceeded, surface runoff will occur - rainfall pattern - dynamics of snow melt - terrain roughness, as expressed in the maximum thickness of a ponding layer In general the nitrogen transport as a result of surface runoff is calculated: as the surface runoff waterflow multiplied with the liquid concentration of solvable nitrogen compounds. In NL CAT model a partitioning of the surface runoff is accounted for. It is assumed that some exchange between ponding water on top of the field and the top soil layer will take place. Therefore, the surface runoff as simulated by the hydrological module is partitioned into three fractions: fraction 1 has the nitrogen concentration of rainfall fraction 2 has the nitrogen concentration of the ponding water on top of the field fraction 3 has the nitrogen concentration of the first soil layer The sum of the portions equals the surface runoff load on the surface water These factors could be extracted from simulation results but are not reported until now. B) SCS Curve Number The SCS (Soil Conservation Service ) curve number method is a simple, widely used and efficient method for determining the amount of runoff from a rainfall in a particular area. Although the method is designed for a single storm event, it can be scaled to find average annual runoff values. It appears in such models as AGNPS, EPIC and SWAT. The requirements for this method are very low: rainfall amount and curve number. The curve number is based on the area's hydrologic soil group, land use, treatment and hydrologic condition: The general equation for the SCS curve number method is as follows: The initial equation (1) is based on trends observed in data from collected sites, therefore it is an emperical equation instead of a physically based equation. After further empirical evaulation of the trends in the data base, the initial abstractions, Ia, could be defined as a percentage of S (2). With this assumption, the equation (3) could be written in a more simplified form with only 3 variables. The parameter CN 96

97 is a transformation of S, and it is used to make interpolating, averaging, and weighting operations more linear (4). With the following chart, the amount of runoff can be found if the rainfall amount (in inches) and curve number is known.there are two advantages of using L-THIA over a manual method. One, the availablity of the data. L-THIA provides the rainfall data for any area in the United States. Two, L-THIA completes this caluculation for every rainfall event for thirty years and then reports the average annual runoff value. Curve number (CN) value used to estimate potential maximum soil retention (S). Values are tabulated in Chapter 9 of NEH-4 for various land covers and soil textures. These values were developed from annual flood rainfall-runoff data from the literature for a variety of watersheds generally less than one square mile in area (USDA- SCS, 1985). CN ( curve number) value varied depend on hydrological conditions, soil type, land use, vegetation, and crop pattern.. 97

98 Land Use Description on Input Screen Agricultural Commercial Description and Curve Numbers from TR-55 Cover Description Cover Type and Hydrologic Condition % Impervious Areas Curve Number for Hydrologic Soil Group A B C D Row Crops - Staight Rows + Crop Residue Cover- Good Condition (1) Urban Districts: Commerical and Business Forest Woods (2) - Good Condition Grass/Pasture High Density Residential Pasture, Grassland, or Range (3) - Good Condition Residential districts by average lot size: 1/8 acre or less Industrial Urban district: Industrial Low Density Residential Open Spaces Parking and Paved Spaces Residential 1/8 acre Residential 1/4 acre Residential 1/3 acre Residential 1/2 acre Residential 1 acre Residential 2 acres Residential districts by average lot size: 1/2 acre lot Open Space (lawns, parks, golf courses, cemeteries, etc.) (4) Fair Condition (grass cover 50% to 70%) Impervious areas: Paved parking lots, roofs, drivesways, etc. (excluding rightof-way) Residential districts by average lot size: 1/8 acre or less Residential districts by average lot size: 1/4 acre Residential districts by average lot size: 1/3 acre Residential districts by average lot size: 1/2 acre Residential districts by average lot size: 1 acre Residential districts by average lot size: 2 acre

99 Water/ Wetlands Color Key Basic Input Value Detailed Input Value Basic and Detailed Input Type Value Notes: (1) Hydraulic condition is based on combination factors that affect infiltration and runoff, including (a) density and canopy of vegetative areas, (b) amount of yearround cover, (c) amount of grass or close-seeded legumes, (d) percent of residue on the land surface (good>=20%), and (e) degree of surface roughness.(2) Good: Woods are protected form grazing, and litter and brush adequately cover the soil. (3) Good: >75% ground cover and lightly or only occasionally grazed. (4) CN's shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type. Nitrate may be transported with surface runoff, lateral flow or percolation. To calculate the amount of nitrate moved with the water, the concentration of nitrate in the mobile water is calculated. This concentration is then multiplied by the volume of water moving in each pathway to obtain the mass of nitrate lost from the soil layer. The concentration of nitrate in the mobile water fraction is calculated: where conc NO3, mobile is the concentration of nitrate in the mobile water for a given layer (kg N/mm H 2 O), NO3ly is the amount of nitrate in the layer (kg N/ha), w mobile is the amount of mobile water in the layer (mm H 2 O), is the fraction of porosity from which anions are excluded, and SAT ly is the saturated water content of the soil layer (mm H 2 O). The amount of mobile water in the layer is the amount of water lost by surface runoff, lateral flow or percolation: where w mobile is the amount of mobile water in the layer (mm H2O), Q surf is the surface runoff generated on a given day (mm H2O), Q lat,ly is the water discharged from the layer by lateral flow (mm H2O), and w perc,ly is the amount of water percolating to the underlying soil layer on a given day (mm H 2 O). Surface runoff is allowed to interact with and transport nutrients from the top 10 mm of soil. Nitrate removed in surface runoff is calculated: where NO3 surf is the nitrate removed in surface runoff (kg N/ha), β NO3 is the 99

100 nitrate percolation coefficient, conc NO3,mobile is the concentration of nitrate in the mobile water for the top 10 mm of soil (kg N/mm H 2 O), and Q surf is the surface runoff generated on a given day (mm H 2 O). The nitrate percolation coefficient allows the user to set the concentration of nitrate in surface runoff to a fraction of the concentration in percolate. C) MONERIS (MOdelling Nutrient Emissions in RIver Systems) The inputs of dissolved nutrients by surface runoff in MONERIS (Schreiber et al. 2003) were determined according to the scheme presented in the figure below. Because the function for the surface runoff used in MONERIS for the German river systems fails for areas with a mean annual precipitation less than 500 mm/a, a new function was developed. Investigations on the possibility of the separation of the total runoff into the main hydrological components were done within other studies on the nutrient emissions in the catchments of the river Spree and Main. The aim was to find approaches for the functional disaggregation of the runoff time series, which is independent on the application of deterministic hydrological models and based on a conceptual time series model. The input data for this model are only measured daily discharges. The model estimates the daily contribution of the baseflow, interflow and surface runoff alone by using the properties of the total runoff according to signal theory and the dynamic behaviour of the time series. 100