Some tube sheds have been planted only for 3-4 years, and some even for 2 years. A layer of purple-red material appears on the soil surface of the shed. When the soil is dry, a layer of white material will appear on the soil surface. This is the soil within the facility. Salinization occurs and becomes increasingly serious. Salinization causes physiological drought and metabolic disorders in vegetables due to water absorption difficulties. It is manifested by slow seedling emergence after seed sowing, low seedling emergence rate, which means that the seedlings will also gradually die; the plants are short, growth is stagnant, root growth is inhibited, and the root tip is new. The roots were brown, and when the roots were severe, the whole roots turned black and rotted and lost their vitality. The leaves curled and lacked green, and the tip was yellow and curled. The stems and leaves died when the damage was severe. I. Causes of Salinization The vegetables in protected areas are often applied with more chemical fertilizers. The amount of fertilizers applied exceeds the amount of absorption. Some of the vegetables that cannot be used are left as "byproducts" and accumulate in the soil. The impact of rainfall on the pipe shed is limited by the leaching of fertilizer components in the soil. The high temperature within the protected area and the large amount of evaporation of soil moisture cause the salt to rise up to the topsoil through the capillaries, while the root system of vegetables is shallow and susceptible to salt damage. When the test soil contained 0.25% of salt, the growth and development of cucumber was inhibited. When it was over 0.50%, the kidney bean would have a large area of ​​death. Second, salinization prevention 1, irrigation salt wash: There are salted pipe shed, can be washed in summer during the washing season large salt, continuous soaking fields for several days, and pay attention to drainage, repeated several times, so that the soil salt leaching out . 2, timely unveiled film: unwinding film to early to mid-June, and accordingly the autumn film was postponed until mid-October as well, then remove the film cover film, the temperature difference between the inside and outside the shed is small, the temperature can be maintained at 20 Around °C, the crops in the shed will not be frozen, and the exposed temperatures in the shed will be higher during the months from June to September. The rainfall will reach 570-600 mm, accounting for about 50% of the annual rainfall, which will facilitate the washing of soil in the shed. The period should also be combined with ploughing the soil and irrigating salt. 3. Balanced fertilization: Mastering balanced fertilization, applying crude organic fertilization, deep fertilization of chemical fertilizers, basal fertilization, combined irrigation after fertilization, so that the main root systems of vegetables are distributed in the lower part of the plough layer, nutrients can be fully and balancedly supplied, and the application is vigorously promoted. Special fertilizers. 4, increase organic fertilizer: organic fertilizer has salt, buffer salt and alkali hazards and other effects, and vigorously promote the use of decomposed farmyard manure, green manure and so on. 5. Rational farming: The soil in the shed is affected by the continuous rising water flow, so that salt and soluble nutrients can easily accumulate on the soil surface. In addition to regular irrigation to make it infiltrate, the simplest and most effective method is soil ploughing. It must be guaranteed twice a year. After deep-dip up to a depth of about 18 cm, the soil can be sunk for about one week after applying the soil. After organic fertilizer or chemical fertilizer is applied, soil and fertilizer will be blended. All the tillage layers will have rich nutrients, which will help the soil absorb irrigation water. Plow bottom.
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