Modeling nitrogen and water management effects in a wheat-maize double-cropping system

Area of Science:

• Agricultural Science
• Environmental Science
• Agronomy

Background:

• Excessive nitrogen (N) and water use in agriculture leads to environmental degradation and threatens system sustainability.
• Intensified double cropping systems, like wheat-maize, are common in regions such as the North China Plain (NCP).

Purpose of the Study:

• To evaluate the Root Zone Water Quality Model (RZWQM) with CERES plant growth modules for simulating crop production, soil water dynamics, and nitrogen (N) leaching.
• To determine optimal N application and irrigation strategies for a wheat-maize double cropping system in the NCP.

Main Methods:

• A field study was conducted from 2000-2002, applying four N treatments (0, 100, 200, 300 kg N ha⁻¹ per crop) under controlled soil moisture (70 ± 15% field capacity).
• The RZWQM-CERES model was used to simulate crop production, soil water content, biomass, grain yield, soil nitrate-N, and plant N uptake.
• Long-term simulations utilized historical weather data to assess N application rates and irrigation strategies.

Main Results:

• The model showed better simulation accuracy for soil water content, biomass, and grain yield (NRMSE 0.11–0.15) compared to soil NO₃⁻-N and plant N uptake (NRMSE 0.19–0.43).
• Simulations indicated that an N application rate of 200 kg N ha⁻¹ per crop, with auto-irrigation to 60% field capacity, is adequate for acceptable yields.
• Reducing N application from 300 to 200 kg N ha⁻¹ per crop could decrease N leaching by approximately 60% without compromising yields.

Conclusions:

• The RZWQM-CERES model effectively simulates key variables in intensive wheat-maize cropping systems.
• Optimizing N fertilizer and irrigation management is crucial for sustainable agriculture, reducing environmental pollution.
• A reduction of over 30% in current N application rates is feasible, leading to substantial environmental benefits.