Monday, November 5, 2007
37-9

Modeling Nitrogen Use Efficiency of Maize Cropping Systems in Pakistan.

Tasneem Khaliq1, Ashfaq Ahmad2, Abid Hussain2, and Gerrit Hoogenboom1. (1) Dep. of Biol. and Agric. Eng, University of Georgia, 1109 Experiment Street, Griffin, GA 30223, (2) Agro-climatology Lab. Department of Agronomy, University of Agriculture, Faisalabad, Pakistan

Mechanistic crop growth models can be excellent tools for evaluation of alternative crop management practices. These models provide an inexpensive and time saving option to determine the requirements for optimizing yield and maximizing net returns for a range of management practices. The goal of this study was to evaluate the potential of the Cropping System Model (CSM)-CERES-Maize to simulate maize yield at different nitrogen levels under varying soil and environmental conditions of central Punjab, Pakistan. This region is characterized as a semiarid region and has extremely high average temperatures; annual average rainfall is 277.6 mm. The model was calibrated and evaluated with field data collected during 2004 and 2005 for three maize hybrids (Bemasal-202, Monsanto-919 and Pioneer 31-R-88) and five nitrogen levels (150, 200, 250, 300 and 350 kg ha‑1) under irrigated conditions of Faisalabad, Sargodha and Sahiwal districts. The results showed that the CSM-CERES-Maize model can be used reliably for prediction of phenology, growth and yield of maize under semiarid conditions, as the average simulation error for grain yield was 9.3 % for 2004 and 8% for 2005. To determine the optimum nitrogen level and suitable maize hybrid, the model was run with 14 nitrogen treatments ranging from 25 to 350 kg N ha-1 and 30 years of historical weather data .The results of both biophysical and economic analysis showed that a minimum of 300 kg N ha-1 is the optimum nitrogen level for all locations. Overall, the variety Pioneer-31-R-88 grown with 300 kg N ha-1 was economically the dominant strategy for the Faisalabad and Sahiwal locations, while the variety Bemasal-202 was economically the best for Sargodha location and the same nitrogen level. This study showed that the CSM-CERES–Maize can be a useful tool for determining the maximum efficiency of cropping systems under semiarid climatic conditions.

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