China has more than 500 million mu of saline-alkali land, and crop growth is greatly restricted. It can be improved by the following methods.

• 1. Flood to wash salt: combining irrigation and drainage, using fresh water to reduce salt in the soil.
• 2. Drainage desalination: pumping water from wells to lower the groundwater level is conducive to desalination and prevention of salt return.
• 3. Biological improvement: planting green manure crops, planting trees, reducing ground evaporation, increasing transpiration, draining salt and preventing waterlogging.