不同压砂厚度和粒径对土壤水盐运移的影响

Influence of thickness and particle size of sand pavement on transfer of water and salinity in soil

为研究砂石厚度和粒径对土壤水盐运移规律的影响,用土柱模拟试验,裸土为参照组（CK）,以砂石厚度（5、10、15cm）和粒径（粗砂、中砂、细砂）为影响因子,研究了不同压砂厚度和粒径对土壤水分蒸发和盐分迁移的规律.结果表明：土壤表层压砂可以抑制水分蒸发,抑制蒸发效果与压砂厚度和细砂的质量分数皆呈正相关关系.压砂可有效地抑制土壤盐分表聚,CK盐分上升发生在0～35cm土层,压砂土壤盐分上升主要发生在0～20cm土层,压砂可缩短盐分在土壤中的迁移深度.随着土层深度的增加,压砂对盐分的抑制作用减弱,抑制盐分表聚作用与压砂厚度和细砂的质量分数皆呈正相关关系,当压砂厚度超过10cm后,厚度的增加对抑制盐分表聚作用提高不明显.综合考虑压砂厚度和粒径对抑制水分蒸发和盐分表聚的作用及经济性,率定出10cm厚的细砂粒径级配对黄黏土保水抑盐效果最优.

In order to study the influence of particle size and the thickness on transfer of soil water and salinity, the bare soil was taken as a contrast group （CK） in soil column simulation test and the thickness of the sand mulch （5,10,15 cm） and its particle size （coarse, medium, and fine） as impact effect to investi- gate the pattern of soil moisture evaporation and salinity transfer in case of different thickness and particle size of the mulch. The results showed that gravel-sand mulch on soil surface can prevent soil moisture e- vaporation and its effect will be in positive correlation with the content of fine sand and mulch thickness. Gravel-sand mulch can effectively reduce soil surface salinity accumulation and salinity of bare soil will increase at the 0-35 cm depth and salinity of gravel-sand mulched soil will increase mainly at the 0-20 cm depth, manifesting that the gravel-sand mulch can decrease the soil salinity transfer depth. With the in- creasing of soil layer depth, the effect of mulch on soil salinity will be weakened and the result of soil surface salinity accumulation reduction will be in positive correlation with the content of fine sand and mulch thickness, the influence of thickness increase on soil surface salinity accumulation reduction will be not ob- vious when the thickness is greater than 10 cm. Considering comprehensiyely the effect of mulch thickness and particle size on refrainment of soil moisture evaporation and surface salinity accumulation as well as its economy, it is rated that fine sand in mulch with thickness of 10 cm will be the best for refraining soil surface salinity accumulation and conserving moisture in loess.