覆砂下微咸水盐度和SAR对水盐入渗及分布的影响

为探讨覆砂条件下灌溉水盐度及钠吸附比对土壤水分入渗过程及水盐分布的影响规律,通过室内土柱模拟试验,研究了灌溉水盐度(EC为0,1.0,2.5,5.0,7.5 dS/m,SAR为5.8(mmol/L)^0.5)和钠吸附比(SAR为 3.9,7.0,12.7,22.7(mmol/L)^0.5,EC为2.5 dS/m)对土壤累积湿润锋和入渗量以及水盐分布的影响.结果表明,随灌溉水盐度的增加,累积湿润锋呈增加趋势,而累积入渗量呈减少趋势.与去离子水相比,7.5 dS/m处理的累积湿润锋较蒸馏水增加了7.0%,而土壤平均含水率降低了36.0%.累积湿润锋和入渗量随灌溉水钠吸附比增加先增大后减小,土壤含水率受灌溉水钠吸附比的影响较小.土壤含盐量随灌溉水盐度增加而呈幂函数增加,但与钠吸附比无明显关系.灌溉水的钠吸附比提高了土壤pH值.

Effect of salinities and sodium adsorption ratio of irrigation water on infiltration and distribution of water and salt under gravel-sand mulching

A series of soil column experiments were carried out to investigate the effects of salinities and sodium adsorption ratios of irrigation water on soil water infiltration process and the distribution of soil moisture and salt under gravel-sand mulching. Treatments included 4 salinities of irrigation water(1.0, 2.5, 5.0 and 7.5 dS/m)with CK of deionized water(EC=0 dS/m)and 4 sodium adsorption ratios(SAR=3.9, 7.0, 12.7, 22.7(mmol/L)^0.5). Results showed that the cumulative wetting front was improved and the cumulative infiltration volume decreased as salinity of irrigation water increased. Compared with deionized water(EC=0 dS/m), the cumulative wetting front increased by 7.0%, and the average soil moisture content decreased by 36.0% with irrigation water salinity of 7.5 ds/m. The cumulative wetting front and cumulative infiltration volume increased first and then decreased with the increase of SAR of irrigation water and the influence of SAR of irrigation water on soil moisture in the profile was little. Salt content in the upper soil increased with the increase of salinity of irrigation water as a positive power function, while there was no obvious relationship between soil salt content and SAR of irrigation water. Soil pH was improved greatly with the increase of SAR of irrigation water.