Characteristics of soil salinity distribution in saline-sodic soil with shallow water table under mulch-drip irrigation in different planting years
地下水浅埋区重度盐碱地不同滴灌种植年限土壤盐分分布特征

To provide the theory basis for the reasonable exploitation and sustainable utilization of saline-sodic soil by mulch-drip irrigation, the effect of mulch-drip irrigation on soil salinity in saline-sodic soil with shallow water table was studied. The method of time-space transformation was used to find out the characteristics of soil salinity distribution in saline-sodic soil planted for 1a, 2a and 3a, at the same time, the uncropped saline waste land adjacent to the experimental site was taken as the control (CK). The results showed that salt was leached downwards at the first planting year; the content and distribution of soil salt were similar at the second and third year of which soil electrical conductivity (EC1:5) was less than the first year; the correlations between EC1:5 and the major ions were significant at the 0.01 level, Cl- and Na+ were the most significant one while HCO3- is the negative one and decreased as the planting year increased. Principal component analysis indicated that the load of Cl-, Mg2+, Ca2+, and Na+ increased with planting years. Regression analysis showed that Cl- and SO42- could be used as major variations to express soil electrical conductivity; an apparently linear correlation was observed between Cl- and EC1:5 while a logarithmic correlation between SO42- and EC1:5. Though the type of soil did not change markedly under mulch-drip irrigation with saline water, soil within 30 cm to the drip line evolved from saline soil to heavy salt affected soil. It can be concluded that mulch-drip irrigation changes the distribution of soil salts and improves the soil environment for root growth, so it can be used to ameliorate and sustainably utilize the saline-sodic soil with shallow water table.