潜水蒸发条件下不同质地剖面的土壤水盐运动

SALT-WATER DYNAMICS IN SOIL PROFILES OF DIFFERENT TEXTURE UNDER GROUNDWATER EVAPORATION CONDITION

Indoor soil column simulating experiment was carried,out to study salt-water dynamics in homogeneous sandy loam,sandy loam with interbedded caly layer and sandy loam with surface clay layer under conditions of different groundwater depths.The results obtained show that the evaporation of groundwater is involved in the two stages,i.e.the wetting of dry soil and the evaporation of soil water in moist soil.fJnder the condition of same groundwater depth the speed of wetting front reaching soil surface in soil column and the amount of daily groundwater evaporaxion followed the order:homogeneous sandy loam>soil with surface clay layer>sandy loam with interbedded clay layer.It was also found that within 1-2m variation range of groundwater table,the influence of interbedded clay layer on groundwater evaporation was greater than that of groundwater depth,and two salt peaks occurred in soil profiles.Under evaporation condition,water content increased gradually from top soil to bottom soil in homogeneuns sandy loam,and interbeded clay layer only affected the water regime in soil above the interbedded clay layer.Under the experimental condition of using groundwater containg 3g/L NaCl for evaporation,secondary alkalization could occur owing to the for anation of Na₂CO₃ and NaHCO₃ in bottom soils.