陇东黄土旱塬不同降水年型作物土壤水分时空分异特征分析

Temporal and Spatial Differentiation of Soil Moisture in Some Crop Fields under Different Year Types of Precipitation in the Loess Tablelands of Eastern Gansu

基于陇东黄土旱塬区作物轮作复种系统田间试验土壤水分观测资料，对几种主要轮作及复种作物在干旱和丰雨两种典型降水年型的农田水分时空分异规律及土壤水分亏缺特征进行了分析．结果表明，在雨养农业条件下，降水年型是引起作物农田土壤水分时空分异的主要原因，土壤水分的垂直分异主要表现在作物用水层深度及强度上，无论干旱年还是丰雨年，均以冬小麦农田土壤用水层深度及强度最大，玉米次之，再依次为马铃薯和谷子；土壤水分的时间分异主要反映在作物生育期内土壤水分随生育进程的波动变化上，冬小麦无论干旱年还是丰雨年都存在明显的土壤水分亏缺，春播玉米和马铃薯仅在干旱年呈现一定的土壤水分亏缺。

In this paper the differential characteristics and deficit laws of soil moisture in some crop fields under different year types of precipitation in the Loess Tablelands of Eastern Gansu were examined on the basis of observations of soil moisture from a 3 year field experiment on the patterns of rotation systems with multiple cropping.The results demonstrated that year types of precipitation were the chief cause of temporal and spatial differentiation in crop field water. The spatial differentiation of soil moisture was largely reflected in the depth and intensity of water consumption by crops; winter wheat was the largest in the depth of water utilization, followed by corn, potato and pearl millet irrespective of dry or wet year. The temporal differentiation of soil moisture was mainly reflected in the variation of soil moisture over the phenostages of crops. The growth of the autumn sown wheat was affected significantly by soil water deficit during the period of early May and late June either in the dry or wet year,whereas drought stress was observed only in the dry year for the spring sown crops. As to the crops for multiple cropping no drougth stress was induced by the dry year.