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Résumé :
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The use of computer models allows the simulation of different N management practices on a long-term basis and their related effects on water quality. The RZWQM (Root Zone Water Quality Model, Version 3.0) was used to simulate the long-term (1978-1992) impacts of N management practices (single N applications at 50, 100, 150, and 200 kg per ha, and single and split N applications at 150 and 200 kg per ha) on NO3-N losses with subsurface drain pools and crop yields under two tillage systems (moldboard plow (MB) and no till (NT)). Simulations conducted in this study were based an input parameters calibrated by Singh et al. (J. Environ. Qual., in press) for NO3-N transport to subsurface drains. However, calibration of some additional parameters was required in this study for long-term simulations. The long-term climatic data and soil properties data for these simulations were obtained from a water quality research site at Nashua, Iowa.The results of this study showed that increasing tares of N applications (50, 100, 150, and 200 kg per ha) resulted in increased NO3-N losses with subsurface drain flows and increased crop yields, However, increasing rates of NO3-N losses and crop yields were not linearly proportional with increasing rates of N applications.
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