Optimizing Nitrogen Fertilization to Enhance Productivity and Profitability of Upland Rice Using CSM-CERES-Rice

Area of Science:

• Agronomy
• Crop Modeling
• Soil Science

Background:

• Nitrogen (N) deficiency limits rice productivity, while imbalanced N application causes economic and agronomic losses.
• Process-based crop models can optimize N management for upland rice, improving production efficiency and profitability.

Purpose of the Study:

• To evaluate the CSM-CERES-Rice model's ability to determine optimal N fertilization rates for upland rice across different sowing dates.
• To identify the economic optimum N fertilization rate (EONFR) specific to each sowing window.

Main Methods:

• Calibrated and validated the CSM-CERES-Rice model using field experimental data from two growing seasons.
• Simulated rice responses to various N fertilization rates (N30–N90) and extended simulations up to N240.
• Determined EONFR for three sowing windows (SD1, SD2, SD3) based on profitability and N utilization.

Main Results:

• CSM-CERES-Rice demonstrated good performance in calibration and validation, with high d-index and low nRMSE values for key parameters.
• Upland rice yield showed responsiveness to N fertilization up to 180 kg N ha−1, with a plateau observed.
• Identified EONFRs of 140, 170, and 130 kg N ha−1 for SD1, SD2, and SD3, respectively.

Conclusions:

• The CSM-CERES-Rice model is a reliable decision support tool for optimizing N management in upland rice.
• Tailoring N fertilization rates to specific sowing windows is more effective than uniform application for maximizing productivity and profitability.