宁南丘陵区苜蓿草地土壤水分时空变异特征研究

为了探明在有限降水及地力瘠薄等资源条件下的苜蓿草地土壤水分时空变异特征，为旱区高效利用有限水资源提供数据支持，对宁南丘陵区主要生长年限苜蓿草地土壤水分开展多点定位监测。结果表明：降水对宁南丘陵区苜蓿草地0~100 cm水分储量增减具有决定作用，苜蓿草地0~100 cm土壤水分表现出雨季来临前持续显著降低，雨季后极显著增加后，缓慢失墒至封冻的趋势，但100 cm以下表现出随生长年限不同各不相同的规律；在100~200 cm层次，以5年生水分补给较多，而2年生补给有限。其中，2年生苜蓿草地100~200 cm土体可作为补水层，在雨季来临之前，对浅层缺水进行一定补给，而5年生只是充当补水过渡层。

Spatial-temporal Variability Characteristics of Soil Moisture on Alfalfa Grassland in Loess Hilly Region of South Ningxia

In order to study spatial-temporal variability properties of soil water on alfalfa grassland under local limited precipitation and land impoverishment conditions in loess hilly region of south Ningxia,and provide data support for efficient utilization of local limited water resource,soil water were monitored on alfalfa grassland based on field multiple positions experiments with different grow years as test treatments.The results showed that the fluctuation of soil water storage at 0-100 cm was decisively effected by the precipitations in loess hilly region of south Ningxia,soil water continuously decreased before rainy season coming,but it was significantly increased after rain,which was consumed gradually until freeze-up period.Soil water on alfalfa grassland with different grow years had different change laws below 100 cm.soil water on alfalfa grassland with 5 grow years had more supplement than 2-years at 100-200 cm.So,the 100-200 cm soil layers of alfalfa grass land with 2-years could be viewed as supplying layer for surface soil water,which could be viewed as transition layer of alfalfa grassland with 5-years.