Flush fertilization is effective, but the key is to master the correct method of use
The application method of fertilizing with water, also called "flush fertilization," is a topdressing method that provides supplemental nutrition during the rapid growth period of crops. Since it is supplemental fertilization, it cannot replace main fertilization methods such as base fertilizer. However, because this method is both convenient and quick-acting, it is widely adopted on vegetable plots and on irrigated land growing cash crops and special edible crops.
At present, flush fertilization is mainly used for topdressing during the vigorous growth season of vegetable crops, and is widely used in greenhouse cultivation and open-field vegetables. Because flush fertilization has a quick fertilizer effect, it generally shows results from 2-3 days to 3-5 days after application, reflected in obvious changes in leaf color and plant height, which very much suits the mentality of some growers who are eager for quick results. Therefore, flush fertilization has been widely adopted for many years. Considering the agricultural production goals of high yield, high quality and high efficiency for crops while also taking environmental protection into account, as well as the current situation of rural labor shortage, in order to give play to the strengths of flush fertilization and avoid its weaknesses, the technical essentials of flush fertilization are briefly described as follows:
????Choose the type of fertilizer
Only water-soluble fertilizers can be applied with water. Among nitrogen fertilizers, commonly used ones include urea, ammonia water, ammonium sulfate and ammonium nitrate; among potassium fertilizers there are potassium chloride and potassium sulfate, and potassium nitrate can also be used. But among phosphorus fertilizers, even water-soluble monoammonium phosphate and diammonium phosphate should not be applied by flushing, because after phosphorus fertilizer dissolves, its mobility is very poor and it is easily fixed, and cannot leach into the root layer with water. The best application method for phosphorus fertilizer can only be to bury it in the soil in layers, so as to improve its utilization rate.
????Get the fertilization timing right
Flush fertilization is better applied during the crop growth period. For example, on fruit vegetables, it can be applied by flushing during the full fruiting period and after picking the melons and fruits. Another example is Chinese cabbage: in autumn planting, it should be applied during the heading period when the temperature drops. Other vegetable crops should also preferably be applied during the growth period.
????Control the amount of irrigation water
Under the border irrigation method, prevent flooding irrigation. When irrigating through channels, the ditch depth and water volume should be appropriate to prevent nutrients dissolved in the water from being lost with the water. Many farmers like to use this topdressing method, and when used well it is effective. But if, in pursuit of superficial results, costs are ignored and large amounts of nitrogen fertilizer are one-sidedly used and flush fertilization is abused, it will lead to excessive vegetative growth of vegetables, reduced quality, lower fertilizer utilization rate, large nitrogen loss, and intensified salinization of soil properties.
Some people crush granular high-concentration compound fertilizer and apply it by flushing; some people apply undecomposed, insoluble solid organic fertilizer or microbial preparations as fertilizer by flushing. These are all inappropriate.
In short, in principle the following points should be mastered: the flush fertilization method should be used at the right time and in the right amount, mainly for topdressing in intensive vegetable cultivation, mainly topdressing nitrogen and potassium. Secondly, four kinds of fertilizer should not be applied by flushing: first, do not flush with phosphorus; second, do not flush with granular compound fertilizer; third, do not flush with solid organic fertilizer; fourth, do not flush with microbial preparations or fertilizers.
( Wei Liaofu )