Abstract

Crop simulation models of different complexity have been developed for predicting the effects of soil, water and nutrients on growth and water productivity of different crops. These models are calibrated and validated for a given region using the data generated from field experiments. Therefore, AquaCrop model was calibrated and validated for grain maize (Single Cross 260) under varying irrigation and nitrogen levels. The experiment was conducted at the research farm of the agricultural college, Islamic Azad University, Shiraz during summer season 2011 and 2012. Irrigation treatments consisted of different levels of depletion of available soil water. The four levels of moisture depletions considered in the study were 20, 40, 60 and 80 percent. Nitrogen application levels were 150 (N₁), 200 (N₂), 250 (N₃) and 300 kg ha^–1. Root Mean Square error (RMSE), Prediction error (P_e), coefficient of determination (R²) and normalized root mean square error (RMSE_n) were used to test the model performance. The model was calibrated for simulating maize grain and biomass yield for all treatment levels with the prediction error 4 < P_e < 5 per cent, 0.64 < R² < 0.81 and 469 < RMSE < 786 t ha^–1. Upon validation, P_e between 10 and 6; R² between 0.65 and 0.76 and RMSE between 1062 and 1293 for grain and biomass yield, respectively. The highest and the lowest accuracy to predict yield and biomass under all nitrogen levels was obtained at I₁ (MAD: 20%) and I₄ (MAD: 80%) treatments, respectively. The results of the present study show that the AquaCrop model simulates aboveground biomass more accurately than grain yield. Also, model cannot provide satisfactory results under severe water stress conditions.

中文翻译：

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使用FAO AquaCrop模型模拟滴灌条件下玉米对土壤可用水分和氮素管理的消耗

摘要

已经开发了不同复杂程度的作物模拟模型，以预测土壤，水和养分对不同作物的生长和水分生产率的影响。这些模型使用现场实验生成的数据针对给定区域进行校准和验证。因此，在不同的灌溉水平和氮水平下，针对谷物玉米（Single Cross 260）对AquaCrop模型进行了校准和验证。该实验于2011年和2012年夏季在设拉子大学伊斯兰学院的农业学院的研究农场进行。灌溉处理包括不同程度的可用土壤水耗竭。研究中考虑的四个水分消耗水平分别为20％，40％，60％和80％。施氮量为150（N ₁），200（N ₂），250（N ₃）和300 kg ha ^–1。均方根误差（RMSE），预测误差（P _e），确定系数（R ²）和归一化均方误差（RMSE _n）用于测试模型性能。对该模型进行校准，以模拟所有处理水平下的玉米籽粒和生物量产量，预测误差为4 < P _e <5％，0.64 < R ² <0.81和469 <RMSE <786 t ha ^–1。验证后，P _e在10到6之间；R ²谷物和生物质产量分别在0.65和0.76之间，RMSE在1062和1293之间。在I ₁（MAD：20％）和I ₄（MAD：80％）处理下，分别获得在所有氮水平下预测产量和生物量的最高和最低准确度。本研究的结果表明，AquaCrop模型模拟地上生物量比谷物产量更准确。此外，在严重的水分胁迫条件下，模型无法提供令人满意的结果。