太行山山前平原主要农作物蒸散量估算方法比较

利用中国科学院栾城农业生态系统试验站1996、1997年气象数据,采用参考作物法和α比值法求得小麦、玉米蒸散量,并与同期大型称重式蒸渗仪监测的小麦、玉米蒸散量进行了比较。结果表明,2种方法估算小麦需水量误差较小。在估算玉米需水量时,丰水年α比值法结果偏低,枯水年参考作物法估算结果偏高。为准确估算作物需水量,建议在确定作物系数时应该尽量采用长系列观测数据分别确定不同年型的作物系数或耗水特征系数,或者采用误差较小的估算方法。

Comparing Two Methods for Calculating Major Crop Evapotranspiration in the Pediment of Mt. Taihang

Based on meteorological data in 1996 and 1997 from Luancheng Experimental Station (LES), one of the major agricultural ecosystem station of Chinese Academy of Sciences, evapotranspirations (ET) of two major crops, winter wheat and maize, were calculated using reference crop method and α ratio method. The actual crop ET measurements from a large-scale weighting lysimeter in LES were used to evaluate the results of both calculations. The evaluation showed that both methods provided good ET estimation for winter wheat of 1996～1997 season. The calculated ET of maize from α ratio method however was lower than the measurements in wet year (1996), and the reference crop method gave higher ET for maize in dry year (1997). To obtain accurate crop ET estimations, we suggest that crop coefficient and　α values should be determined from long term data series, that cover wet, dry and normal years, and whenever possible a method of lower errors should be adapted.