1.Soil salinization
the excessive use of chemical fertilizers is the main reason caused the accumulation of soil salt, especially the accumulation of nitrate. the soil salinization will definitely affect the germination and emergence of seeds, block nutrient absorption, causes poor crop growth, damage the soil structure to death and loss agriculture value.
2. Soil disease by continues cropping
The secondary elements and trace elements has continuously absorbed by same crop, it leads to a nutrients shortage in the soil. Suffered from many years of harmful bacterial continuously reproducing of same crop, and for another reason toxic substance of secreta from last crop remains, the soil get disease.
3. Plough layer become shallow
Due to the long-term mechanical tillage, rolling, and manual work, the plough layer of most of the farmland soil has become shallow, and the effective living soil layer is about 15 cm. The hard and deep plow pan hinders the movement of soil moisture, nutrients and air, and hinders the extension of the root system of crops.