The effect of land use and climate change on the water balance and nitrate leaching is examined for the agriculture on Zealand. It is done by simulations using the dynamic agroecosystems model Daisy set up for a number of representative soil types, recent and future climate data and land management scenarios reflecting the cultivated area on Zealand in the eastern part of Denmark. Future climate data is based on the IPCC A2 climate scenario representing the worst-case scenario. The estimated average global temperature change at 2090-2099 (relative to 1980-1999) for this scenario is 3.4°C with a likely range of 2.0 - 5.4 (IPCC 2001). It is found that evapotranspiration will increase while changes in percolation and drainage depend on soil type and land management. Average weighted nitrate leaching rates are increased by 24% if management practices are kept constant, whereas a status quo is found when management options are changed in form of sawing spring crops one month earlier and replacing some cereal production with maize. Average nitrate leaching per hectare vary between soil types in such a way that the soil with highest nitrate leaching have rates 36% higher than the average and soils with lowest nitrate leaching have rates 33% less than average. This relative difference between soil types is only slightly affected by the climate and land-use change as defined in the scenarios. However, Daisy is sensitive to inputs in the soil organic N pool and a better understanding of how this pool develops in a climate change situation is required if reliable predictions should be obtained together with an assessment of the effect of land management changes.

Keywords: Land use change, climate change, Daisy model, temperate region