Causes of secondary salinization of land
① Irrigation system is not matched, drainage is not smooth, only irrigation but not drainage or heavy irrigation and light drainage, so that a large amount of irrigation water replenishes the groundwater;
② Over-irrigation with flooding, uncontrolled irrigation, resulting in over-irrigation and raising the groundwater level;
③The channel leakage is serious. After long-term water diversion, the groundwater level on both sides of the channel will rise;
④Improper water storage in the reservoir. The water level of plain reservoirs is generally higher than the ground level. If the shut-off facilities around the reservoir are not operating properly, it will inevitably lead to an increase in the groundwater level around the reservoir;
⑤ Paddy and dry fields are located adjacent to each other, and there are no seepage interception facilities around the paddy fields, so that the groundwater level in the dry fields will rise and the land will be salinized.
In addition, extensive farming, unreasonable planting and fertilization, such as not paying attention to leveling the land, increasing organic fertilizer and planting in a timely manner, can also cause the soil to return to salt.