Soil salinization: In general, soil groundwater and surface soil water maintain a certain dynamic balance, the groundwater level is constant, and the ion content in the surface soil is relatively stable. When the climate is dry, the soil evaporation increases and the soil water content decreases, which leads to the groundwater moving up along the soil capillaries and the salt in the soil moving with the water. After water evaporates, salt accumulates on the soil surface. When salt ions reach a certain high concentration, soil salinization will occur. Therefore, most saline-alkali land is distributed in arid and semi-arid areas. Natural soil salinization without human influence is called primary salinization. Soil salinization caused by human activities is called secondary salinization.

Salt: Salt accumulates on the soil surface due to surface evaporation. Waterlogging: the groundwater level is high and the ground is soaked.

Alkali: Due to ion exchange adsorption, the soil cation is too high and the soil is alkaline.

High groundwater level is the main reason for salinization. If the irrigation and drainage system is good, there will be no salinization, that is to say, the salt in the soil comes with the water and goes with it. But I think many people don't know the difference between these two concepts. That is to say, if you see the word soil salinization in that book or paper, it doesn't necessarily mean soil salinization in the true sense, but it may mean salinization and secondary salinization, which is commonly known as "secondary salinization". Refers to the process of soil salinization caused by unreasonable farming and irrigation. It is mainly produced in alluvial plains with high groundwater level, poor groundwater runoff and much soluble salt in groundwater in arid or semi-arid areas, such as North China Plain, Songliao Plain, Hetao Plain and Weihe Plain. Due to the influence of unreasonable human measures, groundwater rises, and when the local evaporation is greater than the precipitation, the salt in the surface layer of soil increases, resulting in soil salinization. The key to prevention and control is to control the groundwater level, improve the irrigation and drainage system, and take reasonable irrigation and other agricultural technical measures to prevent the groundwater level from rising and the soil from returning to salt.