内蒙古河套灌区秋浇对不同类型农田土壤盐分淋失的影响

Effect of autumn irrigation on soil salt leaching in different types of farmland in Hetao Irrigation District of Inner Mongolia

秋浇是河套灌区传统的秋后淋盐、春季保墒的一种特殊灌溉制度 ,秋浇对不同类型农田盐分损失影响的试验结果表明 ,秋浇前白菜地土壤含水率最高 ,向日葵地最低 ,秋浇后 5种农田土壤含水率均较高 ,且彼此间无显著性差异。秋浇后不同土壤剖面盐分的损失量按照表层 (0～ 40cm)、中层 (40～ 80cm)、深层 (80～ 1 2 0cm)依次递减(向日葵地除外 )。不同农田的盐分淋失量按照白菜地、向日葵地、玉米地、小麦 -玉米地、小麦地依次递减。非生长季灌溉下 ,农田土壤 0～ 1 0 0cm土层中盐分的淋失量与土壤储水量的增加量 (灌溉前土壤含水率 <2 50 g·kg- 1 ,r =0 .990 2 )密切相关 。

Autumn irrigation is a particular irrigation system designed to wash soil salt into deeper layers and retain a higher water content for the following spring crops in the Hetao Irrigation District of China.The effects of autumn irrigation on leaching of soil salt in different types of farmland in the Hetao Irrigation District are discussed on the basis of field determination of amounts of soil salt leached in 5 types of farmland.Before irrigation,the soil moisture content was the highest in the cabbage field and the lowest in the sunflower field. Autumn irrigation increased soil moisture in all the fields,showing no significant difference between them.After the autumn irrigation,the leaching of soil salt from the soil profiles was in a decreasing order of surface layer(0-40 cm),middle layer(40-80 cm)and deep layer(80-120 cm)in all the fields except the sunflower field,and in a decreasing order of cabbage field,sunflower field,maize field,spring wheat maize inter planting field and spring wheat field.It can be concluded that the leaching of soil salt during the autumn irrigation in fields without crops is significantly correlated with the increase in soil moisture content in 0-100 cm( r =0.990 2),but not with the content of salt in the soil before irrigation.