Impact of saline soil improvement measures on salt content in the abandonment-reclamation process

Understanding the impacts of desalination treatments on salt migration in saline soil during the farmland abandonment-reclamation process has significance for saline soil development and utilization. In this study, the soil salt content of severely salinized land in Xinjiang, China, was monitored over seven consecutive years using electromagnetic induction (EMI) rapid measurement technology. The experiment involved three different soil desalination engineering treatments and one control in the newly reclaimed, highly saline land (T1: salt isolation treatment at root area with conventional planting; T2: underground tube salt drainage with conventional planting; T3: conventional planting; CK: a natural control). A profile salinity prediction model was built based on the EMI to simulate the three-dimensional spatial distribution characteristics of soil salinity in the test area. The effects of the different saline soil improvement treatments on the distribution of salt content in the soil profile and the effect of desalination were analysed. The results demonstrated the following: (1) the soil salt content in the test area showed an obvious trend of surface salt accumulation. The salt content in the 0−100 cm layers under the different treatments showed decreasing, increasing and decreasing trends with the process of cotton planting, abandonment and reclamation, respectively, with a greater decrease in salt content associated with a longer planting period. (2) The soil salt content obviously decreased under the T1 treatment in the 0−40 cm and 80−100 cm soil layers and in the 20−60 cm soil layers under the T2 and T3 treatments. After the implementation of salinized soil improvement measures and tillage abandonment, a trend of increased salt content was evident in the plough layer under the different treatments; however, engineering improvement measures were able to inhibit salt migration to a certain degree. Under engineered drainage and salt isolation at the root area in combination with agricultural cultivation, irrigation could effectively reduce the soil salt content in the plough layer. These results provide a theoretical basis for soil improvement and utilization in arid areas.