Soil degradation in greenhouses and its remediation technology

Soil salinization and acidification Long-term excessive fertilization, whether fertilizer or organic fertilizer, will cause salt accumulation in the soil surface and secondary salinization. When the soil salt content is higher than 0.3%, it will inhibit the absorption and utilization of nutrients by crops, especially seedling roots. Soil acidification is mainly caused by excessive application of nitrogen fertilizer, which has adverse effects on crop roots and soil microorganisms.

Soil biodiversity is destroyed for the pursuit of high efficiency and long-term continuous cropping, which causes soil microflora imbalance and causes soil-borne diseases such as root-knot nematodes, wilt and blight. This is more common and more serious in monoculture areas such as "cucumber villages" and "garlic villages".

Accumulation of autotoxic substances in soil Autotoxic substances refers to the inhibition of chemical substances secreted, decomposed and eluviated by crop roots on their own, the same species or related plants under long-term continuous cropping conditions. It is a kind of allelopathy, soybean, tomato, eggplant, watermelon, melon and cucumber are easy to produce self-toxic effect when continuous cultivation.

To solve these problems, comprehensive management measures should be taken to repair the soil degradation in greenhouses.

Control soil salinization and acidification by controlling fertilizer amount, fertilization period and the coordination of organic and inorganic fertilizers, nitrogen, phosphorus and potassium fertilizers should be applied in a balanced manner, and organic and chemical fertilizers should be applied rationally. The soil texture was improved, permeability was increased and soil salinization was reduced by proper application of organic fertilizer, straw returning to field and deep tillage. Rotation of different kinds of vegetables, rotation of vegetables and grains, and planting of short growing period of sweet corn, Sudan grass, hairy leaf 苕子, amaranth and other filler crops during the two seasons of vegetable leisure season are conducive to improving soil undesirable properties.

Integrated management of water and fertilizer vegetable roots are mostly shallow and sparse, eggplant fruits, melons, etc., are harvested many times, water and fertilizer should be appropriate many times, the implementation of integration, comprehensive management. This can not only improve the efficiency of fertilizer and water utilization, but also eliminate or reduce the soil degradation and environmental pollution caused by large amounts of water and fertilizer. It is recommended that the greenhouse eggplant fruits, melons and fruits vegetables, in the case of synchronous fertilizer and water, a small number of times, the base fertilizer is generally applied 300 to 400 kilograms of organic fertilizer, and the mu of green application is a large amount of element nutrition water-soluble fertilizer 5-7 kilograms. Using irrigation and fertilization technology, the amount of fertilizer and water application can be further reduced, and the green amount of new fertilizer (water-soluble fertilizer containing humic acid) is generally 6-8 kg per mu.

The straw bioreactor technology is to open a ditch under the planting row or around the greenhouse, put the straw and fermentation compound bacteria, prepare the material C/N ratio, moisture and ventilation status like high temperature compost, cover the film and punch holes, and carry out straw fermentation under field conditions. The decomposed straw can be converted into soil and used as fertilizer. The released carbon dioxide is an urgent carbon source fertilizer for greenhouses in early spring; The fermentation heat can increase the ground temperature by 3℃~5℃. This technology has been popularized and applied in greenhouses in Shandong and northern China.