黄土丘陵区不同立地条件下紫花苜蓿地土壤水分动态变化

研究了定西市安家沟流域不同立地条件紫花苜蓿Medicago sativa土壤水分的变化。结果表明：阳坡土壤水分均小于阴坡土壤水分，紫花苜蓿在不同立地条件下土壤水分都发生了显著的变化，但其顺序为阴坡台地>阴坡坡地>阳坡台地>阳坡坡地。不同立地类型各土壤层次的月变化存在显著差异，阴坡台地和阴坡坡地第1茬（4-6月）的土壤水分极显著高于阳坡台地和阳坡坡地的土壤水分，二者间没有显著差异，而在7月后，阴坡台地极显著高于其他立地条件的土壤水分。不同立地条件下紫花苜蓿每层深度土层的土壤水分都发生了不同程度的变化，在整个垂直剖面上都在降低，40～100 cm土层土壤水分降低最多。

Soil moisture dynamics of alfalfa pasture at different eco-sites in Gullied Loess Area

Soil moisture dynamics of alfallfa pasture at different eco-sites in Anjiagou valley was studied.The results showed that the soil moisture changed significantly at different sites.The soil moisture in north hill was lower than in the south,the order southern ladder > northern slope > southern ladder > northern slope.The monthly changing of water content was dramatically different,southern ladder and southern slope were higher than other sites from April to June,and both showed no significant.But southern ladder significantly was higher than other sites after July.At different eco-sites,the soil moisture was changing at each layer in alfalfa pasture;it was decreased at all vertical sections,most moisture was at 40-100 cm depth.