Evaluation of the CERES-Maize water and nitrogen balances under tile-drained conditions

The CERES-Maize model was developed to investigate how variations in enviro nmental conditions, management decisions, and genetics interact to affect c rop development and growth. A tile drainage subroutine was incorporated int o CERES-Maize to improve soil-water and nitrogen leaching under subsurface tile drainage conditions. The purpose of this work was to evaluate the soil -water, soil-nitrogen, tile drainage, and tile-nitrogen loss routines of CE RES-Maize for file-drained fields in Iowa. An analysis was conducted based on information collected from a study of 36 plots consisting of five manage ment systems during a 4-year period from 1993 to 1996; at Nashua, IA. The m odel was calibrated for each plot using data from 1994 and 1995, and valida ted using data from 1993 and 1996. Temporal soil-water contents and water f low from tile drains were calibrated to an average root mean square error ( RMSE) of 0.036 cm(3) cm(-3) and 2.62 cm, respectively, compared to measured values. validation trials gave an average RMSE for soil-water and tile dra inage of 0.046 cm(3) cm(-3) and 5.3 cm, respectively. Soil-nitrate and tile -nitrogen flows were calibrated, with an RMSE of 6.27 mu g NO3 g(-1) soil(- 1) and 3.21 kg N ha(-1) soil(-1), respectively. For the validation trials, the RMSE for soil-nitrate content and cumulative tile-nitrate flow was 6.82 mu g NO3 g(-1) soil(-1) and 8.8 kg N ha(-1), respectively. These results i ndicate that the new tile drainage algorithms describe water and nitrate mo vement reasonably well, which will improve the performance of CERES-Maize f or artificially drained fields. (C) 2000 Elsevier Science Ltd. All rights r eserved.