What is the reason why the surface layer of indoor soil in greenhouse turns red and how to improve it?

1. The surface layer of greenhouse soil turns red, which is mainly due to the accumulation of vegetable excessive fertilization and chemical fertilizer residues in greenhouse, resulting in soil salinization, and sulfide, sulfate, organic salt and inorganic salt remain in the surface layer soil, resulting in hardening and salinization of greenhouse soil. Therefore, a layer of purplish red substance will appear on the soil surface.

2. Improvement measures:

(1) Grain-vegetable rotation and vegetable-rice rotation in greenhouse can be implemented where conditions permit; In summer, especially in rainy season, remove the top film of the greenhouse and let the natural rain wash away and leach the salt.

(2) Balanced formula fertilization to avoid excessive fertilization; Apply more organic fertilizer, chicken manure and pig manure, return straw to the field, and apply less chemical fertilizer; Try to apply less organic fertilizers and chlorine-containing fertilizers with high salt content.

(3) Eradicate 2-3 cm soil on the surface of greenhouse soil, replace it with fertile soil, and improve the soil to remove salt; Improving soil structure and activating soil are beneficial to the extension of lateral roots of greenhouse vegetables, enhancing the ability of vegetable roots to absorb nutrients and water, and improving the organic matter content of greenhouse soil.

Extended data:

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The optimum pH value for growing vegetables in greenhouse is between 6 and 700.5. High and 7.5 are alkaline soils, and low and 6 are acidic soils. Alkaline and acidic soils will inhibit crops' absorption of nutrients in the soil, which will lead to the high concentration of soil solution, which will lead to the inability of crop roots to breathe effectively, the survival of beneficial bacteria in the soil, and the inhibition of root formation, which will lead to slow crop growth and reduced yield.

Applying a large number of crushed and retted crop straws and a large number of organic fertilizers as base fertilizers, supplemented by commercial beneficial bacterial fertilizers such as EMTM stock solution, can improve the physical and chemical properties of soil and make crops obtain high yield.