Modelling N and water movement in wheat-corn double cropping systems with RZWQM

Abstract

Simulation of water and nutrient processes can enhance intensive agriculture in China to help feed about one-fifth of the world s population in a sustainable manner. In this study, we calibrated and tested the RZWQM model to assess its potential as a nitrogen (N) management tool in a double-cropping system comprised of winter wheat (Triticum aestivum L.) and corn (Zea mays L.) at Luancheng, North China Plain. Data used for model testing included crop growth, soil water, and soil-crop N of field trials conducted from 2001 to 2003 in four split doses (200 to 800 kg N ha-1). In general, biomass, plant N uptake, and residual soil N predictions showed greater departures from measurements than total profile (0-180 cm) soil water and grain yield. Soil profile water contents were predicted within ±2% and biomass prediction errors were between -2.9% and 2.1%. Grain yield was consistently underpredicted, but only by 5% to 7%. Other prediction errors ranged from -0.8% to 5.7% for Crop N uptake, 0.3% to 6.0% for grain N uptake, and -13.6% to 28.7% for residual soil N. The calibrated model predicted an average yearly loss of about 43% of applied N to the environment.