Types, harms and improvement of saline soil in Songnen Plain

Saline soil is an extremely difficult and modified soil, widely distributed around the world. According to UN-UNESCO and FAO, the world's saline soil area is about 9.54x 10(8)hm(2), and there is a growing trend, every year in 1.0x10(6)-1.5x10(6)hm(2) speed growth, the effective utilization of land resources to the world is the most serious threat. The total area of saline-alkali land in China is about 9.91 x 10(7)hm(2), including the Songnen Plain, which is called one of the three major saline soil concentrations in the world. The Songnen plain is an important grain producing area in China, and the saline soil occupies most of the Songnen plain, so it is of great significance to study the saline soil and improvement in Songnen plain.