Trade-off between wheat yield and drainage under current and climate change conditions in northeast Germany

In the temperate climate of northeast Germany, a trade-off exists between water use in agricultural crop production and groundwater recharge which is important for urban water supply, irrigation, forestry and peat protection. The APSIM-Nwheat model was used to analyze the impact of climate change scenarios on deep drainage (DD), the water loss below the maximum root zone as the main source of groundwater recharge, and wheat production for two main soil types. A linear and a nonlinear climate scenario were used in this study: The linear scenario for 2001-2050 was based on a simple linearly modified historical climate record from 1951 to 2000. The nonlinear scenario used the same 1951-2000 historical climate record but combined it nonlinearly with a Global Circulation Model climate scenario for 2001-2050. Simulation results showed different distributions of deep drainage and grain yield with the linear and nonlinear scenarios, but no difference in the 50-year averages. Hence, a linear manipulation of climate records can be as effective for climate change impact studies on deep drainage and grain yield as nonlinearly manipulated climate data, if long-term average changes are of main interest. The simulation results indicated that a trade-off between deep drainage and grain yields can be potentially controlled through N management. However, such control mechanism was more effective under current climate conditions than under future climate and on a better water-holding silt soil compared to a poorer water-holding loamy sand. It is suggested that areas with poor water-holding soils should be managed extensively for groundwater recharge harvesting while better water-holding soils should be used for high input grain production. Crown Copyright. (c) 2006 Published by Elsevier B.V. All rights reserved.