Flanders in the European Union

Transcription

1 Using residual nitrogen measurements in nutrientmanagement policies: the case of Flanders Kevin Grauwels -> Jeroen Buysse Challenges in fertilization and manure management Vic, 17 December 2014 Flanders in the European Union 1

2 Intensive agriculture on a small surface Competition for land Pressure on environment N and P excess Evolutionof surfacewater qualityin Flanders Average nitrate concentrations in surface waters mg NO3-/l MAP monitoring network 2

3 Evolutionof groundwaterqualityin Flanders Evolution in average nitrate concentrations in groundwater weighted average nitrate concentrations (mg NO3-/l) Monitoring campaign Nitrate residue measurements: the instrument Measuring residual nitrate in agricultural soils To a depth of 90 cm Sample taken between 1 October and 15 November =estimation of amount of nitrate possibly leaching to ground and surface water Instrument used since

4 Nitrate residue: a tool rather than a goal Goal is improving water quality Nitrate residue to create awareness Nitrate in the soil during autumn will possibly leach during winter Monitoring Water quality in MAP monitoring stations Too far away for the farmers Results do often not appeal to an individual farmer Nitrate residue Very direct and confronting Appealing to a farmers professional pride: evaluating farmers fertilization practices Evaluation of farmers fertilization practices Amount of residual nitrate in the soil evaluated against thresholds 4 different threshold values define which measures have to be taken by the farmer 1 st threshold value Increased risk of nitrate leaching in case of exceedance Set at a level to protect water quality 2 nd, 3 rd & 4 th threshold value Increments above 1 st threshold value Differentiation of threshold values Crop Soil Focus area 4

5 1 st threshold value 2 nd threshold value 3 rd threshold value 4 th threshold value No measures Measures Group 1 Measures Group 2 Measures Group 3 Measures Group 4 Overview of the current 1 st thresholds Crop Focus area Non-focus areas Sand Other Clay Sand Other Clay Grassland Maize Beets Other arable crops Horticulture & potatoes

6 Measures in case of exceedance Imposed when 1 st threshold is exceeded The type and severity of the measures depend on the extent to which the first nitrate residue threshold value is exceeded Accompanying measures Generating change in behaviour of farmers Forcing towards efficient fertilization Measures in case of exceedance Soil sampling and professional fertilisation advice Get to know your soil before you apply fertiliser Fertilisation plan Consider in advance where and when you should apply fertiliser in function of crop need instead of manure availability Make a timely planning for processing excess manure production Auto-control of nitrate residue: soil sampling and analysis by accredited laboratories but farmer has to pay Catch crops Decreased fertilisation standards above 3rd and 4th threshold value 6

7 Evolution in number of parcels sampled Number of parcels Sampling distribution represents crop distribution in Flanders agriculture 1% 1% 1% 2% 9% 4% 5% 33% 44% Grassland Maize Beets Cereals Potatoes Vegetables Fruits Ornamental horticulture Other crops 7

8 Evolution in nitrate residue measurements Nitrateresiduein kg NO 3 - -N/ha Average Median Weighted average 04 October Evolution in mean nitrate residue per crop type Grassland Maize Beets Cereals Potatoes Vegetables Fruits Ornamental horticulture Other crops 8

9 D Haeneet al, 2014: linking fertilization to nitrate residue Peer reviewed publication on environmental performance of fertilization standards for 5 main fodder and arable crops in Flanders Grassland, maize, winter wheat, sugar beets and potatoes Metadata-analysis of fertilization trials in Flanders Linking Fertilization application rates Crop yield Residual mineral nitrogen Turning point in fertilization Decrease of nitrogen efficiency Increase of residual nitrate and N- losses Process factor: linking residual nitrate to water quality Leaching of nitrate = caused by net precipitation surplus Flanders: mean net precipitation surplus = 300 mm During transport from soil to water body nitrogen transformation processes Denitrification Differences in concentration between the bottom of the soil profile and the water Process factor (denitrification factor) Average for Flanders = 2,1 9

10 Conclusions Instrument closest to the water quality Great awareness raising value Confronting farmers with individual fertilization practices Improvement through imposing measures in stead of fines Some disadvantages Soil samples = large variability Influenced by weather Threshold difficult to reach in certain crops (potatoes, vegetables, ornamental horticulture) 10