Analysis of maize growth for different irrigation strategies in northeastern Spain

Water availability is the key factor determining maize yields in NE Spain. Irrigation is needed to obtain economic yields but it is costly and water s upply is sometimes insufficient. The aim of this research was to test a sim ple simulation model for evaluating different irrigation strategies, especi ally under water-limited conditions. The LINTUL model was adapted and param eterized using experimental data from the 1995 season. Most parameters were obtained from experiments, although some were taken from the literature. T his model is based on the concept of light use efficiency, incorporates a s oil water balance and simulates phenology, crop leaf area, biomass accumula tion and yield. It was tested on independent data from the 1995 and 1996 se asons under different irrigation treatments. The model predicted the flower ing date within +/-5 days of the observed values, Leaf area index was predi cted satisfactorily, except under extreme water-stress conditions, where it was overestimated. In general, soil moisture content and yield were accura tely predicted. In the 1996 experiment measured yields ranged from 6.4 to 1 3.6 t ha(-1) and simulated yields from 6.5 to 12.2 t ha(-1). These results show that the LINTUL model can be used as a tool for exploring the conseque nces on maize yields of different irrigation strategies in NE Spain. Analys is of the model identified a process that strongly affects yield loss due t o drought, but for which present understanding is still insufficient: the e ffects of drought on leaf senescence and canopy architecture. (C) 2000 Else vier Science B.V. All rights reserved.