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Title: Modeling Nitrogen and Water Management Effects in a Wheat-Maize Double-Cropping System

Author
item FANG, Q - QINGDAO AG UNIVERSITY
item Ma, Liwang
item YU, QIANG - CHINESE ACADEMY OF SCIENC
item Malone, Robert - Rob
item SASEENDRAN, S - COLORADO STATE UNIVERSITY
item Ahuja, Lajpat

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2008
Publication Date: 11/1/2008
Citation: Fang, Q., Ma, L., Yu, Q., Malone, R.W., Saseendran, S.A., Ahuja, L.R. 2008. Modeling Nitrogen and Water Management Effects in a Wheat-Maize Double-Cropping System. Journal of Environmental Quality. 37:2232-2242.

Interpretive Summary: Water and nitrogen (N) inputs in agriculture have enhanced crop yields but their use in excess of crop demand is leading to surface and groundwater quality problems, and contributes to shortages of fresh water resources. In this study, the Root Zone Water Quality Model (RZWQM) was evaluated with data from four N treatments (0, 100, 200, and 300 kg N ha–1) in an irrigated wheat-maize double cropping system from 2000 to 2002, in the North China Plain (NCP). Simulated soil water, biomass and grain yield were better than simulated soil nitrate-N and plant N uptake. The model was then used to explore optimum levels of water and N for the system using long-term weather data and built-in automatic irrigation options. Simulations responded well to different N and water management strategies, and revealed that, at 200 kg N ha–1 N application rate, triggering irrigation at 45% of the field capacity and recharging to 70% field capacity in the 0-50 cm soil profile were adequate for obtaining acceptable yield levels in this double cropping system. Results also showed potential savings of about 50% of the current N rate in the region, which can reduce about 90% of the N leaching without compromising crop yields. Adopting deficit/limited irrigation management developed in the NCP recently, more N fertilizer could be saved by matching crop N and water demand with soil supplies and by considering the interactions between crop seasons. We concluded that the model is a very valuable tool to develop optimum N and water management strategies in wheat-maize cropping systems in the NCP.

Technical Abstract: Excessive nitrogen (N) and water use in agriculture causes environmental degradation and can potentially jeopardize the sustainability of the system. To quantify the impact of different agricultural practices on production and environment, field research under various soils and climates are necessary. Agricultural system models are also viable tools for integration of research results from one or more sites and extrapolation beyond the experimental climates and soils. In this study, the Root Zone Water Quality Model (RZWQM), with the CERES-Wheat (Triticum aestivum L.) and Maize (Zea mays L.) plant growth modules incorporated, was evaluated with data from four N treatments (0, 100, 200, and 300 kg N ha–1) in an irrigated wheat-maize double cropping system from 2000 to 2002, in the North China Plain (NCP). Simulated soil water, biomass and grain yield were better than simulated soil nitrate-N and plant N uptake. The model was then used to explore optimum levels of water and N for the system using long-term weather data and built-in automatic irrigation options. Simulations responded well to different N and water management strategies, and revealed that, at 200 kg N ha–1 N application rate, triggering irrigation at 45% of the field capacity and recharging to 70% field capacity in the 0-50 cm soil profile were adequate for obtaining acceptable yield levels in this intensified double cropping system. Results also showed potential savings of about 50% of the current N rate in the region, which can reduce about 90% of the N leaching without compromising crop yields. Adopting deficit/limited irrigation management developed in the NCP recently, more N fertilizer could be saved by matching crop N and water demand with soil supplies and by considering the interactions between crop seasons. We concluded that the model is a very valuable tool to develop optimum N and water management strategies in wheat-maize cropping systems in the NCP.