绿洲农田土壤斥水性及其影响因素

Characteristics of Soil Water Repellency and Its Causes in Oasis Cropland

土壤斥水性(Soil Water Repellency, SWR)指水分不能或很难湿润土壤颗粒表面的现象,对农业水管理、土壤水入渗、农化污染物运移及土壤侵蚀有重要影响,土壤斥水性在绿洲化过程中的变化特征及其影响因素尚不明确。在甘肃临泽绿洲分别选取未开垦的沙地(0年)及开垦10、30、50、100年绿洲农田表层土壤(0~5 cm),分别测定土壤有机碳含量、土壤质地(砂粒、粉粒、黏粒)和土壤pH,并用毛管上升法测定土壤斥水性。结果表明:土壤斥水性随着开垦年限的增加而不断增加。不同开垦年限土壤的'土-水'接触角58°~89°,差异显著(P<0.001)。土壤有机碳含量、土壤质地和土壤pH均与'土-水'接触角存在显著的回归关系(P<0.001)。逐步回归分析的结果表明,绿洲化过程中土壤有机碳含量和pH共解释了土壤斥水性72.1%的变异。因此,在绿洲农田进一步研究土壤斥水性对土壤水运动的影响应更多关注土壤有机碳和pH两大因素。

Soil Water Repellency(SWR)can be defined as the phenomenon that a soil does not wet spontaneously when water is applied on the surface,which has an important impact on agricultural water management,soil water infiltration,agro-pollutants transport and soil erosion.However,little is known on the SWR in oasis cropland.This purpose of the study was to analysis characteristics of soil water repellency and its causes in Linze oasis cropland.Soil samples at the depth of 0-5 cm were selected in the natural sand(0 year)and reclaimed 10 years,30 years,50 years and 100 years oasis cropland.Soil organic carbon,soil texture(sand,silt&clay)and soil pH was measured,and soil water repellency was determinated by the capillary rise method.The results showed that soil water repellency increased with the increase of reclamation years.The'soil-water'contact angle ranged from 58°to 89°and was significant difference among different reclaimed years cropland(P<0.001).Soil organic carbon,soil texture and soil pH all had significant regression relation with soil-water contact angle(P<0.001).The results of stepwise regression analysis showed that soil organic carbon and pH explained 72.1%variation of soil water repellency,and effected more soil water repellency than soil texture.All results of the study indicated that further research on soil water repellency should pay more attention to soil organic carbon and pH.