新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的关系

为了研究新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的定量关系,对试验区自然状况下的土壤含水量、表层土壤含盐量、地下水埋深、地下水矿化度和潜水蒸发量进行了原位监测,模拟了潜水蒸发量与地下水埋深的关系,定量分析了弃荒地自然条件下地下水埋深、地下水矿化度对土壤表层盐分的影响,建立了表层土壤含盐量与地下水埋深、地下水矿化度的经验模型。结果表明:在5~50 cm土层,土壤质量含水率随土层深度增加而增大;地下水埋深、地下水矿化度对表层土壤盐分有显著的影响,当地下水埋深为定值时,表层土壤含盐量与地下水矿化度呈线性正相关;当地下水矿化度为定值时,表层土壤含盐量与地下水埋深呈线性负相关;土壤盐分表聚现象明显,不同地下水埋深条件下表层土壤含盐量随累计潜水蒸发量的增加而增大,表层土壤积盐速率随地下水埋深的增大而减小,地下水埋深为25 cm条件下表层土壤积盐速率约是地下水埋深为50 cm的表层土壤积盐速率的2倍多。

Relationship between salt accumulation in topsoil of deserted land and groundwater in areas with shallow groundwater table in Kashi, Xinjiang

To quantify the relation of salt accumulation in the topsoil of deserted land with groundwater in areas with shallow groundwater table in Kashi, Xinjiang, in-situ monitoring was performed of soil water content, salt content in the topsoil, depth and mineralization of groundwater and phreatic evaporation in the experimental area under natural conditions; simulation was done of the relationship between phreatic evaporation and groundwater table; quantitative analysis was conducted of the effect of groundwater table and mineralization on salinity of the topsoil; and in the end an empirical model was established for relationships of salt content in the topsoil with water table and mineralization of the groundwater. Results show that within the 5~50 cm soil layer, soil water content (SWC) increases with depth;. the effects of water table and mineralization of the groundwater are significant on salinity of the topsoil; and soil salt content is in a positive linear relationship with mineralization of the groundwater when groundwater table is a const, but in a negative linear one with groundwater table when mineralization of the groundwater is a const. The phenomenon of surface accumulation of soil salts indicates that soil salt content increases with increasing cumulative phreatic evaporation regardless of groundwater table and salt accumulation rate in the topsoil decreases with increasing depth of the groundwater table. The salt accumulation rate in the topsoil of a deserted land with groundwater table deep at 25 cm is twice as high as that with groundwater table deep at 50 cm. The findings of the study could serve as scientific basis for amelioration of salt-affected soils and prevention of soil secondary salinization.