PJB-2024-180
Simulation of Water-Nitrogen Movement and Nitrogen Utilization Rate in Black Soil Maize Fields Using the WHCNS Model
Xin Sun
Abstract
Straw returning is essential for soil conservation and mitigating wind erosion in semiarid regions bearing black soil areas. Quantitative studies on soil water–nitrogen dynamics and crop growth processes under complete straw returning are fundamental for establishing a rational farmland management system. We employed the soil water heat carbon nitrogen simulator (WHCNS) to simulate soil profile water-nitrogen distribution and crop yields under different fertilization treatments, namely CK (no fertilization), T1 (compound fertilizer), T2 (compound fertilizer + straw returning), and T3 (humic acid fertilizer + straw returning). We calibrated and evaluated the performance of the WHCNS model by using soil water content, nitrate nitrogen content, aboveground dry matter mass, and yield data collected from the Meilisi Daur District experimental farm in Qiqihar, Heilongjiang Province, in 2022. We also simulated the effects of different fertilization methods on spring maize field evapotranspiration, crop yield, and water-nitrogen use efficiency. The results indicate that the hydraulic parameters Qs and n significantly impacted the soil water content in the parameter sensitivity analysis. In contrast, SLAmax had the largest impact on soil nitrate nitrogen content among crop parameters, and Ts was the most influential factor on crop yield. The relative root mean square errors of simulated and observed soil water storage, nitrate nitrogen content, and aboveground dry matter mass were all lower than 32%. Consistency indices for the 0–60 cm and 60–100 cm soil layers were greater than or equal to 0.68 and 0.30, respectively. Finally, the Nash coefficients were within reasonable ranges. The evapotranspiration rate under the straw returning treatment (T2) was 6.33% lower than without straw returning (T1). T2 exhibited the highest water-nitrogen use efficiency among all treatments, and compared with T1 and T3, water-nitrogen use efficiency increased by 10.27%, 7.78%, 26.71%, and 48.15%, respectively. These findings suggest that straw returning can effectively reduce evapotranspiration and improve resource utilization efficiency. Overall, the calibrated WHCNS model can reliably simulate the dynamics of soil water–nitrogen movement and crop growth under straw returning in the semiarid regions of northeastern China.
Keywords: Soil, WHCNS model, evapotranspiration, water use efficiency, nitrogen use efficiency
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