Key benefits of compost use for the soil-plant system

Transcription

1 Workshop on Ecologically Sound Use of Biowaste in the EU Brussels, 31 May 1 June 2006 Key benefits of compost use for the soil-plant system Rainer Kluge State Agricultural Analytical and Research Institute Augustenberg Karlsruhe, Germany

2 Advantages of composts (Overview) Saving potentials Nutrients Value giving materials Phosphorus Potassium Magnesium Nitrogen Organic Matter Humusrepro Lime Fertilization Soil improvement

3 Sources Value giving materials and nutrients in composts Current test results on quality parameters of composts povided by Bundesgütegemeinschaft Kompost e.v., Germany

4 Value giving materials: organic matter (OC)/ humus annually balance input by compost/ requirement of soil Humus-C in t/ha 2,5 2,0 1,5 1,0 0,5 Input of compost 6-7 t/ha DM Input of compost 10 t/ha DM Medium humus requirement * High humus requirement ** to + Means 0,0 total reproducible optimum suboptimum Humus-C-input by compost Humus requirement of soil Crop rotation: * medium Maize/ W.Wheat/ W.Barley ** high Sugarbeet/ W.Wheat/ W.Barley

5 Value giving materials: organic matter (OM)/ humus annually balance input by compost/ requirement of soil Humus-C in t/ha 2,0 1,5 1,0 0,5 Input of compost 6-7 t/ha DM Input of compost 10 t/ha DM Medium humus requirement * High humus requirement ** About 50 % of OM input to + Means 0,0 reproducible optimum suboptimum Humus-C-input Humus requirement of soil Crop rotation: * medium Maize/ W.Wheat/ W.Barley ** high Sugarbeet/ W.Wheat/ W.Barley

6 Value giving materials: lime annually balance input by compost/ requirement of soil CaO in dt/ha 6,0 5,0 4,0 3,0 2,0 1,0 0,0 6-7 t/ha DM 10 t/ha DM lime requirement * Means Input light heavy by Compost Soils * Preservation liming

7 Nutrients annually balance input by compost/ removal by harvest Input of compost 6-7 t/ha DM Input of compost 10 t/ha DM Medium removal by harvest * High removal by harvest ** Means Nutrients in kg/ha to (-) - to + + N P 2 O 5 K 2 O MgO Crop rotation: * medium G.Maize/W.Wheat/W.Barley ** high S.Maize/W.Wheat/W.Barley Removal: without straw

8 Sources Value giving materials and nutrients in composts Current test results on quality parameters of composts povided by Bundesgütegemeinschaft Kompost e.v., Germany Effects on soil fertility and plant growth Results from long-term field studies in South-West-Germany, LUFA Augustenberg Results on compost use in the humus reproduction of soils, Reinhold und Partner, Germany

9 Experimental basis of the project Long-term field studies with compost on five typical locations Soils: predominantly medium to heavy Quality-assuranced composts France France France France 12 years Forchheim Weierbach 9 years Ellwangen Heidenheim Uniform experimental design Uniform crop rotation Maize/W.Wheat/W.Barley South-West West-Germany Stockach Switzerland

10 Long-term studies with compost in Baden-Württemberg Experimental basis of the project Location Region Soil type Content of clay % Type of compost Duration (a) Forchheim Rheinebene loamy sand 10 biowaste 12 Weierbach Kraichgau silty loam 27 garden mat. 12 Stockach Hegau silty clay loam 26 biowaste 12 Ellwangen Ostalb silty clay loam 29 biowaste 9 Heidenheim Ostalb silty loam 27 biowaste 9

11 Experimental design Nr. of Factors of experiment variant Compost application min. N fertilization annually in t/ha DM annually in % of Optimum 1 without without 2 without 50 3 without without Optimum range for plant production 7 10 without without Extreme range

12 Organic matter (OM) Effects of compost on humus content/ humus reproduction of soil Average input with compost rates of annually 6 7 t/ha DM: OM input = 2,5 3,0 t/ha DM Result of the project: Humus content of the soil after 8 resp. 11 years Practical consequences: Stabilization resp. slight increase of humus contents High performance of humus reproduction more than 50 % of the total C in compost consists of stable humus C forms Sustainable humus reproduction is ensured by these stable forms of humus Compost rate in t/ha DM ,2 0,6 % Humus content without compost = 2,5 % 0,0 0,5 1,0 1,5 Increase of humus content in %

13 Lime (CaO) Effects of compost on the ph value/ state of lime of the soil Average input with compost rates of annually 6 7 t/ha DM: Input of lime = 2,0 4,0 dt CaO/ha Result of the project: ph value of the soil after 8 resp. 11 years Practical consequences: Stabilization resp. slight increase of the ph values Compost rate in t/ha DM ,2 0,4 ph ph value without compost = 6,4 Lime input corresponds to preservation liming 0,0 0,2 0,4 0,6 0,8 Increase of ph value

14 Supply of nutrients Effects of compost on the soluble nutrient contents (P, K, Mg) of the soil Average input with compost rates of annually 6 7 t/ha DM: Nutrient supply in kg/ha P 2 O 5 = K 2 O = MgO = Result of the project: Nutrient contents of the soil after 8 resp. 11 years Practical consequences: High fertilizer effect of P und K - Contents remain at starting level resp. increase slightly - High fertilization efficiency, input basic supply - Full accounting in the fertilization balance both nutrients are limiting factors of compost application Smaller fertilizer effect of Mg Compost gift in t/ha DM starting level starting level P 2 K 5 2 O Contents Contents of of soluble soluble nutrients nutrients in in mg/100 mg/100 g

15 High input of total Nitrogen by compost correct charging in the fertilizer balance a) N utilization Result of the project: N utilization and N fertilization effect is very small, increases only gradually b) Effects on nitrate content of soil Charging in the N fertilizer balance (annually): Compost 20 % Plant nutrition Short-term (1 3 years) = 3 5 % 80 % Medium-term (5 10 years) Humus = 8 10 % reproduction Result of the project: Increase with regular application of compost: only about 5 10 kg/ha Conclusions: N mineralization takes place relatively slowly and thus can be controlled Strong organic N sorption prevents unexpected N mobilization events and leaching into the groundwater Precautions measures: Regular control of nitrate contents of soils Reduction of additional N fertilization by %

16 Physical and biological soil characteristics Soil improvement by use of compost (1) Improved parameters Effects on soil use Physics and water regime of soils Increased stability of soil crumbs more stable soil structure enhanced pressure resistance improved workability saving fuel consumption less erosion reduction of soil losses Faster warming up of soils Soil porosity Bulk density Increased water capacity and moisture infiltration growth promotion in spring improved aeration and drainage of soils buffers negative effects of weather extremes increased water storage reduces drying stress better permeability help to avoid stagnant water

17 Physical and biological soil characteristics Soil improvement by use of compost (2) Improved parameters Effects on soil use Soil biology Increased microbial biomass Increased enzyme activities increased biological activity activation of soil life better tilth of soil higher phytosanitary loadability decrease of pathogens in the soils closer C/N ratio in soils improved mineralization of the organic material increased N mineralization gradual enhancement of the soil fertility improved soil use soil conservation

18 Benefits of composts for plant cultivation conclusions (1) Composts = organic NPK fertilizers benefits = sum of all particular effects Main medium-term benefit Humus reproduction of soils Advantages of compost high portions of carbon, just right for reproduction build-up of humus soil improvement in general better use of soil, stabilization of crop yield increasing importance for maintenance/ enhancement of soil fertility Because: organic matter for the soil will become less available (!) negative humus balance - in commercial farms humus is often lacking - increasing sales of straw (to industries, for renewable energy production) - other resources are less suitable (i.e. liquid manure)

19 Benefits of composts for plant cultivation conclusions (2) Additional benefits Fertilization and liming = Saving potentials Input lime stabilization of ph value subtitutes preservation liming Input nutrients (P, K, Mg) high fertilization efficiency subtitutes basic supply Nitrogen only low fertilization efficiency It is a matter of economical and ecologic reason to use composts preferably in agriculture, because they optimal fulfil the requirements for a sustainable cycling Best Option reliable hygienic material to avoid problems with bad hygiene sustainable humus reproduction enhancement of the soil fertility broad nutrient effects saving of fertilizers (basic supply) minor and calculable risks environmentally safe use of composts