黄土高原沟壑区苜蓿地土壤水分剖面特征研究

对黄土高原沟壑区不同种植年限苜蓿地土壤深层水分特征的分析表明,受降水影响0～2m土层水分变化较大,2m以下由于没有水分的补给,出现了干燥化现象。苜蓿在生长前期主要利用上层土壤水分,土壤水分恢复也是从上层开始,下层的干层则难予恢复。10、15、23年生苜蓿分别在9、10.8和11m处水分含量趋于稳定,达到土壤干层的下限。土壤水分的变异系数随土层深度的增加而减小,水分含量趋于稳定。在0～9m土层土壤水分亏缺较大,亏缺量大于年均降水量。

Soil water distribution characteristics of alfalfa with different planting years in the gully region of loess plateau

The distribution characteristics of soil water of alfalfa with different planting years in the gully region of the loess plateau were studied. The results showed that the soil water content in 0—2m layer was affected by annual precipitation. Soil layer below 2m was drier without water supplying, forming a dry layer. Alfalfa had used the soil water of (upper) layers on first growing season years, and the soil water had been renewed from upper layers, however renewing the soil water of the lower layers was difficult. The soil water content of 10,15 and 23 years alfalfa didn't change (significantly) in 9m,10.8m and 11m soil layers respectively, and the dry layer was disappear. The variance coefficient of soil water decreased with the increase of depth. It pointed that the great water deficit caused by evapo-transpiration was significant in 0—9m layer, the amount of deficiency was more than annual precipitation.