生化黄腐酸对盐碱土水盐运移特征的影响

Effect of Biochemical Fulvic Acid on Water and Salt Transport Characteristics in Saline-alkali Soil

为改善盐碱胁迫农田土壤水盐环境、缓解西北干旱地区土地次生盐渍化,通过一维垂直入渗试验,对不同生化黄腐酸施加量(0、1、2、4、8 g/kg)条件下新疆地区中度盐碱土的水盐运移特征及入渗模型参数进行了研究。结果表明:在入渗结束后,与未施加生化黄腐酸相比,施加量为1、2、4、8 g/kg条件下的土壤累积入渗量分别增加了1.00%、4.67%、7.14%、3.44%,土壤水分入渗速率随着生化黄腐酸施加量的增加呈现先减小后增大的变化趋势,土壤剖面平均体积含水率分别增加了8.90%、17.70%、20.41%、11.67%;在0~20 cm土层,土壤平均脱盐率分别为5.29%、27.04%、42.77%、14.74%。Philip、Green Ampt模型和代数模型均能较好地模拟不同生化黄腐酸施加量下土壤水分入渗特征,且模型参数与生化黄腐酸施加量间存在函数关系。与未施加生化黄腐酸相比,施加生化黄腐酸后土壤吸渗率S和土壤饱和导水率K_(s)均减小,且随着施加量的增加均呈现先减小后增大的变化趋势,施加量4 g/kg时S、K_(s)最小;湿润锋处吸力S_(f)和综合形状系数α呈现先增大后减小的变化趋势,施加量4 g/kg时S_(f)、α最大。施加生化黄腐酸能够显著影响土壤水分入渗和水盐运移特征,且施加量4 g/kg对于中度盐碱土具有较好的保水和脱盐效果。

Chemical amendment is an effective measure to improve soil water and salt environment under saline alkali stress and alleviate land secondary salinization in arid areas of Northwest China.The water and salt transport characteristics and infiltration model parameters of medium saline-alkali soil at different biochemical fulvic acid(BFA)application rates(0 g/kg,1 g/kg,2 g/kg,4 g/kg and 8 g/kg)were investigated through the one-dimensional vertical infiltration test.The results showed that after the infiltration,compared with no application of BFA,the cumulative infiltration amount at the BFA application rates of 1 g/kg,2 g/kg,4 g/kg and 8 g/kg was increased by 1.00%,4.67%,7.14%and 3.44%.The soil water infiltration rate was decreased first and then increased with the increase of BFA application,respectively,the average volumetric water content of soil profile was increased by 8.90%,17.70%,20.41%and 11.67%,respectively.In addition,at the 0~20 cm soil layer,the average desalination rates were 5.29%,27.04%,42.77%and 14.74%,respectively.At the same time,the Philip model,Green Ampt model and algebraic model could well simulate the soil water infiltration regulation at different BFA application rates,and there was a functional relationship between model parameters and BFA application rates.Compared with no application of BFA,the soil infiltration rate S and the soil saturated hydraulic conductivity K_(s) were decreased,and showed a trend of first decrease and then increase with the increase of the BFA application amount,and the minimum value was obtained at application rate of 4 g/kg.The suction S_(f) at the wetting front and comprehensive shape factor α were increased first and then decreased,and the maximum value was obtained at application rate of 4 g/kg.Therefore,the application amount of BFA significantly affected the characteristics of soil water and salt transport,and the application amount of 4 g/kg had obvious effects on water conservation and desalination of medium saline-alkali soil in Xinjiang.