Irrigation of farmland, pay attention to four kinds of fertilizers, do not flush them.

The application method of flushing fertilizer with water is also called "flushing fertilization". Generally, it is a kind of topdressing to provide supplementary nutrition during the period of rapid crop growth. since it is supplementary fertilization, it can not replace the main fertilization methods such as base fertilizer. However, because this method is both convenient and quick, it is widely used in vegetable fields and irrigated fields where cash crops and special food crops are planted. At present, flushing fertilization is mainly used for topdressing in the vigorous season of vegetable crop growth, and is widely used in greenhouse planting and open field vegetables. Because the fertilizer effect of rush fertilization is fast, it can be effective from 2-3 days to 3-5 days after irrigation, which is reflected in the obvious changes in leaf color and plant height, which is in line with the psychology of some eager growers. Therefore, rush fertilization has been widely used for many years. Considering the agricultural production goal of high yield, high quality and high efficiency of crops and the lack of rural labor force, in order to give full play to the advantages of "flushing fertilization" and avoid its disadvantages, the technical essentials of "flushing fertilization" are briefly described as follows: 1. The correct selection of fertilizer types of flushing fertilization can only be applied with water. Urea, ammonia, ammonium sulfate and ammonium nitrate are commonly used in nitrogen fertilizer; potassium chloride and potassium sulfate can also be used in potash fertilizer. And phosphate fertilizer, even if it is water-soluble monoammonium phosphate and diammonium phosphate, do not apply, because the mobility of phosphate fertilizer is very poor after dissolution, it is easy to be fixed, and can not infiltrate into the root layer with water. The best way to apply phosphate fertilizer is to bury it in the soil layer by layer to improve its utilization rate. 2. The nutrient content of a single rush fertilization must be reduced. In the cultivation of high-yield vegetables, the amount of pure nitrogen should be controlled at 2-3 kg / mu, especially the nitrate nitrogen should be controlled below 2-3 kg / mu. The limited amount of potassium fertilizer (potassium oxide) is generally 2-4 kg / mu; otherwise, there will be a great waste and loss of nutrients. It not only reduces the nitrogen use efficiency, but also may cause water pollution. It is generally appropriate to apply fertilizer twice in the whole growth period. 3. During the period of irrigation and fertilization, if vegetables are applied in the period of full fruit and after picking melons and fruits, or in the heart stage of Chinese cabbage, the temperature and soil mineralization are decreased in the planting of autumn cabbages, and vegetable crops are suitable for mass growth. 4. The amount of irrigation is controlled by border irrigation to prevent flood irrigation. In canal irrigation, the ditch depth is appropriate to the amount of water to prevent the loss of nutrients dissolved in water. Many farmers like to use this way of topdressing, which is effective when it is well used. However, in order to pursue the surface effect, regardless of cost, one-sided use of a large amount of nitrogen fertilizer and abuse of flushing fertilization will lead to excessive growth of vegetables, decline of quality, decrease of fertilizer use efficiency, large nitrogen loss, and aggravate the salinization of soil properties. Some people break the granular high-concentration compound fertilizer and then apply it; some people use unmature and insoluble solid organic fertilizer or microbial preparation as fertilizer, which is inappropriate. In short, in principle, we should grasp the following points: the way of flushing fertilization should be used timely and appropriately, mainly for topdressing in intensive vegetable cultivation, mainly nitrogen and potassium. There are four kinds of fertilizers, do not apply phosphorus; second, do not apply granular compound fertilizer; third, do not flush solid organic fertilizer; fourth, do not rush microbiological agents or fertilizers.