CERES model application for increasing preparedness to climate variability in agricultural planning-risk analyses

Thirty-year frequency analyses of seasonal nitrogen (N)-leaching, proved that ten of wheat and only one of maize vegetation seasons were susceptible to significant (10-45 kg N/ha/year) ground water pollution on Chromic Luvisol. Simulated precise irrigation scenario did not influence drainage in vegetation period. Another risky situations occurred under maize in the wettest fallow state after extremely dry vegetation (in one more of the studied years) when up to 18-33 kg N/ha/year might be leached. Earlier wheat sowing (on the 1st instead on the 15th of October) and nitrogen fertiliser split application timed as close as possible to the period of maximum crop N-uptake reduced nitrogen available for leaching under both crops. Drainage-controlling irrigation scheduling decreased maize drainage in fallow state by 30-40% in half of the years and caused 10-12% yield losses in average and dry seasons on Chromic Luvisol.