Effects of agro-economic decisions on nitrate leaching

Abstract

Nitrate leaching has significant influence on groundwater quality. Climate and land-use change will affect its future intensity and spatial distribution. This chapter concentrates on effects resulting from changes in land-use due to agro-economic decisions, and Chap deals with the effects of climate change. Coupled simulations with the DANUBIA simulation system (plant growth, balances of carbon, nitrogen, water, energy, agro-economy) were performed for four districts in the Upper Danube catchment for the years 2011-2060. The agro-economic model which simulates land-use change based upon economic decision was run using two scenarios: (1) continuation of the status quo and (2) discontinuation of premium payments after 2013. Meteorological drivers and cultivation (timing, fertilisation) were kept constant. Results for the years 2049-2058 were compared to a model run with constant land-use Row crop and spring cereal area increases. The area of forage and miscellaneous crops decreases. The extent of winter cereals increases in districts dominated by arable land but decreases in grassland-dominated districts. Despite the land-use changes, spatial patterns of nitrate leaching changed little. Critical nitrate concentrations (>75 mg l�’1) were calculated particularly in regions with intensive agriculture on organic soils. The direction of changes in nitrate concentration and nitrate load are usually identical. Changes of nitrate leaching of max ±4 % occur in the grassland-dominated districts, while for the districts dominated by arable land, one shows an increase (<4 %) and the other a decrease (<9 %). Compared to the effect of climate change, the investigated agro-economic scenarios exert only small effects on nitrate leaching.