中国北方旱农地区农田水分动态变化特征

北方旱地区域农田水分特征的主要影响因子是自然降水和农田蒸散量。在区域尺度上，农田潜在蒸散量是半干旱偏旱区＞半湿润偏旱区＞半干旱区。半干旱偏旱区农田水分平均潜在亏缺量为517 mm，最大亏缺量为968 mm，最小亏缺量为162 mm。半干旱区旱地农田水分平均潜在亏缺、最大亏缺和最小亏缺量分别为274、688和－34 mm，半湿润偏旱区上述3个参数分别为157、469和－180 mm。由于降水的时空变化，不同类型地区农田土壤水分储存量也产生了区域分异，3种不同类型地区农田土壤水分在农作物不同发育期储存量的变化是半湿润偏旱区＞半干旱区＞半干旱偏旱区。旱地作物耗水主要来源于生育期间的有效降水和播种前的土壤蓄水。

Soil Moisture Dynamic Characteristics of Dryland Field in Northern China

The soil moisture characteristics of dry land field in Northern China are affected by precipitation and evaportranspiration. The field evaportranspiration in semiarid and arid zone is the largest, that in semi humidity arid zone the middle, and that in semiarid zone the smallest. The average water deficit amount is about 517 mm in dry semiarid zone, the maximum value 968 mm,the minimum value 162 mm; And in semiarid zone, the average value, the maximum value and the minimum value are 274, 688 and -34 mm, respectively; in semihumid arid zone, the 3 parameters are 157, 469 and -180 mm, respectively. Due to the temporal and spatial variation of precipitation, the deposited amount of soil water has their spatial, temporal variation too in 3 different zones, and their values in crop growth season are semihumid arid zone is the largest, that in semiarid zone the middle, and that in semiarid dry zone the smallest. The crop water use is from precipitation and soil water before sowing.