Technology and Mechanism of Soil Salinization Using Gravel Barrier

The use of gravel barrier to block capillary action provides a new idea for soil salinization improvement. In order to demonstrate the feasibility of soil salinization improvement using gravel, a test site was established in the typical salinization distribution area of Hangjin Rear Banner in the west of Hetao irrigation area. Different structures and buried depths of gravel layers were explored to identify the improvement effect of soil salinization. Soil salinity, pH, cation exchange capacity (CEC) and the percentage of sodium exchange were monitored for one year. The results show that among the 7 groups of different treatments, the treatment with buried depth of 60-80 cm and particle diameter of 1 cm and 3 cm was the best condition. The average soil EC value of at the four depths from the surface to 40 cm decreased by 55.9%. The gravel barrier buried deeply and laid down in a fine-grained and coarse manner, which have higher porosity in the bottom layer of the gravel barrier, can cut off the capillary at the deeper depth of unsaturated zone. Therefore, it can decrease effectively the rising height of soil capillary, and inhibit the salt in the deep soils from upward, namely "salt return".