Adaptation, calibration, and validation of the agro-ecological zone model for Urochloa humidicola pastures

ABSTRACT The agro-ecological zone model (AZM-FAO) is used to describe agricultural scenarios and the impact of climate risk on crops and, when adapted, can be used to simulate the yield of forage species under adverse conditions. The study aimed to test the performance of the AZM-FAO model to simulate the yield of Urochloa humidicola grass in Mato Grosso. The model was adapted for two locations with different soil and climate conditions, with data from two experiments (E1 and E2). The morphophysiological variables of the pastures, the physical-hydric variables of the soil, and the meteorological data of the experimental period were analyzed. The model calibration was based on changes in the yield response coefficient to water (Ky) and the minimization of deviations between simulated and observed data. The model presented a satisfactory performance for the two analyzed locations. In experiment E1, the RMSE was 29.86% (acceptable), and the c index was 0.86 (optimal) in the calibration phase, maintaining the same results in the validation. In E2, there was an improvement in the performance of the model, with RMSE and c index going from 30.74% (poor) and 0.84 (very good) in the calibration to 17.50% (good) and 0.92 (very good) in the validation step, respectively. The AZM-FAO model adapted for Urochloa humidicola grass can be used with good accuracy to simulate the forage yield of this forage in the southern region of Mato Grosso.

摘要：农业生态区模型（agro-ecological zone model，AZM-FAO）可用于描述农业情景以及气候风险对作物的影响；经适配改造后，还可用于模拟逆境条件下牧草物种的产量。本研究旨在验证AZM-FAO模型在马托格罗索州模拟湿生臂形草（Urochloa humidicola）产量的性能。本研究针对两处土壤与气候条件存在差异的站点对模型进行了适配，所用数据来自两项试验（E1与E2）。研究分析了牧草地的形态生理变量、土壤的物理水文变量以及试验周期内的气象数据。模型校准以水分产量响应系数（Ky）的调整以及模拟值与观测值间偏差的最小化为基础。模型在两处分析站点均表现出良好的性能。在试验E1的校准阶段，均方根误差（Root Mean Square Error，RMSE）为29.86%（可接受水平），一致性指数（concordance index，c index）为0.86（最优水平），且验证阶段的结果保持一致。在试验E2中，模型性能得到了提升：校准阶段的均方根误差与一致性指数分别为30.74%（较差）和0.84（优秀），而在验证阶段分别优化至17.50%（良好）与0.92（优秀）。经适配改造后的湿生臂形草专用AZM-FAO模型，可在马托格罗索州南部地区以较高精度模拟该牧草的产量。