The use of greenhouses to cover plastic film to grow vegetables is to artificially create a suitable ecological environment, adjust the vegetable production season, regulate market demand, and promote high-quality and high-yield vegetables, which is one of the effective means to increase farmers' income. From the survey of farmers in most greenhouses, the benefits are obvious. However, some farmers have planted greenhouse vegetables, and the effect is not satisfactory. Except for the variety of vegetables, the restriction of “four evils†is often an important factor causing losses. The so-called "four evils" are fat, phytotoxicity, drought and flail.
First, fat damage. In fact, it is the hazard of salt accumulation. The main reason is that the soil is salinized by partial application of chemical fertilizer or excessive fertilization. The problem that occurs after the occurrence of fertilizer damage is to inhibit the development of vegetable roots and weaken the function of water and fertilizer absorption. Second, the concentration of soil solution is too large, and the vegetable plant body undergoes reverse osmosis, resulting in physiological wilting or leaf edge dryness; It is a toxic gas hazard; the fourth is to cause vegetable deficiency.
Second, phytotoxicity. There are obvious phytotoxics and the symptoms are obvious. There are hidden phytotoxics, the symptoms are latent or delayed to the squat vegetables. The reasons for the phytotoxicity are as follows: the choice of pesticides is not correct or misuse of herbicides; the second is the application concentration is too large; the third is the purchase of inferior pesticides; the fourth is not to avoid high temperature seasons. After the phytotoxicity, some vegetables quickly lose their green leaves; some produce focal spots and perforations; some fall, fall, fall, or deform; the most serious whole plants wither.
Third, drought damage. It is one of the most critical factors restricting the development of greenhouse vegetables. The reasons for this are: the improper selection of vegetable greenhouses and the lack of water sources in the local area; the second is that although there are water sources, the water quality is not good; the third is that the water volume is relatively sufficient, but the ditch, canal and irrigation facilities are not matched, and the water is difficult to lead, and the water is sighing. Drought damage not only affects the timely sowing of vegetables, but also affects the normal growth of vegetables. At the same time, it brings great difficulties to the management of fertilization and drugs. The effects of drought damage sometimes exceed fertilizer and phytotoxicity.
Fourth, even the obstacles. It is in the same greenhouse that the same type or the same kind of vegetables are grown year or quarter, and the yield and product quality are declining year by year. The reasons for the obstacles are: the same kind or the same kind of vegetables prefer a certain nutrient element, such elements are not prone to deficiency in time; the second is the accumulation of soil pathogenic bacteria causing dead seedlings such as blight and blight; Third, the secretion of substances in the roots of the same vegetable can easily lead to the loss of balance of soil microbial community structure, resulting in soil aging.
Therefore, in order to enable plastic greenhouses to produce more high-quality vegetables, in the selection and production process of sheds, lessons should be learned and effective countermeasures should be taken in a timely manner.
First of all, we must choose a shed site and improve the water system. Before determining the greenhouse, it is necessary to check whether the shed site has sufficient water source and whether the water source is polluted. With sufficient water supply, it is necessary to open trenches and canals to facilitate water diversion and drainage. Where conditions permit, a water supply faucet should be installed in each shed. Sprinkler irrigation facilities should also be provided for the standard height.
Second, we must balance fertilization and promote the steady growth of vegetables. First, it is necessary to apply fully decomposed organic farmyard manure all the year round; secondly, it is necessary to apply refined organic fertilizer and high-energy organic fertilizer, such as Huimanfeng and Dilean; thirdly, it is necessary to change the application of nitrogen and phosphorus to reduce nitrogen, stabilize phosphorus, increase Potassium, with the application of micro-fertilizer; Fourth, the appropriate amount of fertilization; fifth, the occurrence of fertilizer damage in a day, to spray a variety of active liquid fertilizer to alleviate the hazard.
Again, use medicines to ensure the safety of vegetables. First, minor phytotoxicity occurs. The method of strengthening fertilizer and water management can be used to restore the normal fertility function of vegetables. Second, it is necessary to select the correct pesticides, especially the herbicides. The third is to keep the dose and concentration of pesticides and avoid them. Repeat the use of a pesticide; the fourth is to avoid mixing pesticides at random; the fifth is to avoid high temperature; the sixth is that the equipment applied with herbicide must be cleaned before reuse.
Fourth, we must rotate and adjust the vegetable cultivation environment. First, eggplant, tomato, and melon-prone vegetables are required to be replaced with other vegetable varieties in different seasons or seasons. Second, greenhouses that are prone to continuous obstacles need to be added with organic fertilizer to improve soil. Third, soil re-tanning agents are used. Inhibition of pathogens; Fourth, in response to the lack of soil, timely supplement of the lack of nutrients.
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