Effects of climate change on nitrate leaching

Abstract

Nitrate leaching has significant influence on groundwater quality. Climate and land-use change will affect its intensity and spatial distribution. This chapter concentrates on climate effects and Chap additionally deals with effects of land-use change. Coupled simulations with the DANUBIA simulation system (plant growth, balances of carbon, nitrogen, water, energy) were performed for four districts in the Upper Danube catchment for the years 1996-2005 and 2011-2060. Meteorological drivers were generated using a statistical weather generator and trends from a regional climate model. Land-use and cultivation practice (timing, fertilisation) were kept constant. Slightly increasing nitrate concentrations in the leachate were simulated during the scenario periods. District mean nitrate concentrations vary between 10 and 44 mg la. Highest local concentrations were found for intensively used cropsites on organic soils. Maximum concentrations occur in years where reduced percolation more than compensated for the generally declining nitrate loads. This agrees with a reduction of the soils mineral nitrogen content in the end of the growing season. However, some results for individual crops deviate from these general findings. Especially grassland shows an increase in nitrate loads due to a slightly decreased vegetation uptake, increasing the availability for leaching. This indicates the need to adjust the fertilisation scheme under climate change conditions. The results show that climate changes alone will not lead to serious changes in nitrate leaching.