基于APSIM模型的宁夏半干旱区苜蓿灌溉模拟验证和应用

Validation and application of Lucerne irrigation simulation based on APSIM model in semiarid area of Ningxia

基于宁夏4个试验点的试验数据和同期气象资料,对APSIM模型进行了充分地校准和验证.结果表明,APSIM模型达到了较高的精度,各验证项模拟值和实测值均表现出良好的相关性,决定系数R2在0.6～1.0之间,D值在0.78～0.99之间.在此基础上,利用APSIM模型模拟了不同灌溉情况下不同灌溉量对苜蓿（Medicago sativa L）的干草产量、蒸发蒸腾量和水分利用效率的影响.认为灌溉是宁夏半干旱地区苜蓿增产的重要因素.200 mm的灌溉量是苜蓿干草产量由增加到减少的转折点.苜蓿不同生育阶段对水分的敏感度不同.分枝期和现蕾期最大灌水量为50 mm,超过50 mm会引起产量降低.蒸发蒸腾量（ET）与灌水量呈线性显著相关,决定系数R2达到0.826,P＜0.01.苜蓿水分利用效率与灌溉量不成正比,当灌溉量增加到100 mm时,水分利用效率达到最大、为54.2 kg/hm2＆#183;mm,随后逐渐降低.较大的灌溉量不利于苜蓿水分利用效率的提高.

APSIM model was carefully calibrated and validated by using measurement data and meteorological data over the same period at four sites in Ningxia. The results showed that there were good correlations between simulated values and measured values with determination coefficient R2 ranging from 0.82 to 1, and D value ranged from 0.78 to 0.99. Based on this, different irrigation amounts were used to simulate Lucerne dry matter production （GY）, evapotranspiration （ET） and water use efficiency （WUE）. The results showed that irrigation was the important factor of Lucerne production in semiarid area of Ningxia. 200 mm irrigation amount was the turning point of Lucerne dry matter production from increasing to reducing. Lucerne in different growing stage showed different sensitivity to water. The biggest irrigation amount was 50 mm in branching and budding stage, and production would decrease when irrigation amount more than 50 ram. Evapotranspiration （ET） linear significantly correlated to irrigation amount, and determination coefficient R2 reached 0.826 and P〈0.01. Water use efficiency could not invariably increase with the increasing irrigation amount, it would reach 54.2 kg/hm2·mm when irrigation increased to 100 mm, then reduced. While more irrigation amount went against the improving of water use efficiency.