1, the farming layer becomes shallow. Due to long-term mechanical ploughing and manual operation, most farmland soils are shallow, and the effective live soil is about 15 centimeters, plus rainfall and irrigation. The plough bottom moves up and thickens, forming a hard and deep barrier layer. This hinders the movement of soil moisture, nutrients and air, affecting the extension of crop roots, the less soil storage capacity and the decreasing drought resistance.
2. Soil organic matter content decreased. The decrease of soil organic matter will cause a series of soil problems, such as soil acidification and secondary salinization, soil structure destruction, soil fertility and soil borne diseases.
3. Soil structure is damaged and hardened seriously. Due to the lack of organic fertilizer supplement and unreasonable farming and unreasonable irrigation, the massive application of chemical fertilizer has aggravated the destruction of soil aggregate structure, resulting in more serious soil compaction, which directly affects the natural vitality and self-regulation ability of the soil.
4, soil tends to acidification. Soil acidification is mainly due to the excessive use of chemical nitrogen fertilizer and physiological acid fertilizer, resulting in the increase of acidic substances in soil and acidification of soil. Soil acidification will cause soil nutrient loss, soil harmful heavy metals activation, soil harmful microorganisms, especially parasitic fungi increase, accelerate soil impoverishment and soil borne diseases.
5. Soil secondary salinization. Due to the excessive use of chemical fertilizers over a long period of time, salt accumulation in the soil has been continuously accumulated, and nitrate accumulation has become more serious. Light affects seed germination and seedling emergence, impede nutrient absorption, and crop growth is bad. Heavy stress causes physiological drought, nutrient absorption obstacles, and soil structure damage, which can lead to salt damage and death.
6. The proportion of nitrogen, phosphorus and potassium in soil is out of proportion. In the daily management, the vast majority of farmers do not apply fertilizer proportionately, often only a large number of nitrogen and phosphorus fertilizers are applied, resulting in the lack of potassium. In the long run, no trace element fertilizer is applied, resulting in the depletion of trace elements in the soil. The proportion of nitrogen, phosphorus and potassium in the soil is out of proportion, and the nutrient proportion between the macro elements and the trace elements is out of balance.
7, farmland soil pollution. Excessive use of chemical fertilizers, pesticides, residual pollution of agricultural film, pollution of untreated organic fertilizers, and pollution of continuous cropping and pests and diseases will spill over once the soil self purification ability is exceeded. This will lead to the imbalance of soil ecology, resulting in a large number of dead soil beneficial organisms and beneficial microbes, the decrease of soil biological population, the deterioration of soil physical and chemical properties, the decrease of soil activity, the deterioration of soil function, and the loss of agricultural utilization value.
8. Soil disease caused by continuous cropping of crops. Continuous cultivation of one or the same crop in the soil, due to the lack of continuous absorption of the micronutrient elements needed by the crop, also enables the corresponding bacteria to propagate year after year, accumulate in the soil, and the root exudates of the previous crops accumulate as toxic substances and form the disease soil.