在低定额灌溉条件下 ,农田土壤水分常处在水分胁迫条件下 ,对水分胁迫下农田土壤水分蒸散模型进行了研究 ,在水分胁迫下实际蒸散量 (ET)与潜在蒸散量 (ETm)之间关系为 :ET =KW·ETm·KW,与根层土壤有效水含量具有直线相关性 .模型中考虑根系分布的影响 ,能明显提高模型精度 ,为低定额灌溉确定农田实际耗水量提供科学依据 ,并提高农田土壤水分利用率 Under the low irrigation condition, the soil moisture of farmland always under the condition of water stress, the model of soil water evapotranspiration under water stress was studied. Under the condition of water stress, the actual evapotranspiration (ET) and potential evapotranspiration (ETm) The relationship is: ET = KW · ETm · KW, which has a linear correlation with the effective water content in the root soil.The model can significantly improve the accuracy of the model by considering the effect of root distribution, and provide a scientific basis for determining the actual water consumption of farmland in low- And improve farmland soil water use efficiency