Why use foliar fertilizer? What are the misunderstandings in applying foliar fertilizer?
Foliar fertilizer, as a nutrient supplement for leaves, is increasingly accepted by farmers. Foliar fertilization can directly enter the body from the leaves and participate in the metabolism of crops and the synthesis of organic matter. Therefore, it is faster and more effective than soil fertilization. So, why use foliar fertilizer? What are the misunderstandings of foliar fertilizer application? Let's take a look at it together.
Why use foliar fertilizer?
1. Supplement the deficiency of root fertilization
When crop roots are inconvenient to fertilize, such as in the late crop growth period, root vitality declines and the ability to absorb fertilizer decreases;
Or when the soil environment is unfavorable to the growth of crops, such as excessive water, drought, excessive soil acidity, and excessive alkalinity, the absorption of crop roots is blocked and crops are premature senescence;
However, crops need to recover quickly. If root application cannot meet the needs of crops in time, only foliar sprays can quickly supplement nutrients and meet the needs of crop growth and development.
Specifically, in the seedling stage of crops, the roots are not fully developed, and the leaves can be sprayed with nitrogen, phosphorus and potassium macroelement fertilizers to supplement the crop's nutrient requirements, and at the same time, some growth regulators can be used to promote crop growth.
Before and after the flowering of crops, the demand for phosphorus and potassium is relatively large. Therefore, at this time, the supplementary elements of the leaves are mainly phosphorus and potassium, such as the source of phosphorus and potassium. At the same time, the demand for boron during the flowering period is relatively large, and auxiliary spraying of boron fertilizer is required.
During the period of fruit expansion, the demand for nitrogen and potassium is relatively large, and the main nutrients for the leaves are nitrogen and potassium, such as potassium nitrate. During the fruit coloring period, the demand for potassium is relatively large, and the leaf supplement is mainly potassium fertilizer.
In the late stage of crop growth, due to the degradation of the roots, the crop's ability to absorb nutrients is reduced. Therefore, at this time, it is necessary to supplement various nutrients such as nitrogen, phosphorus and potassium through the leaves. For some melon and fruit crops, especially those that require a large amount of calcium, calcium should be supplemented by leaves intentionally from the beginning of fruit setting.
2. Supplement nutrition quickly
In the process of crop growth, crops have shown certain nutrient deficiencies. Since it takes a certain period of time for nutrients to be absorbed by the crops using soil fertilization, it cannot alleviate the symptoms of crop deficiency in time.
At this time, using foliar fertilization can make nutrients quickly enter the plant body through the leaves and solve the problem of nutrient deficiency.
For example: when the tree body is weak, the leaf color is yellow, and the growth is slow, the plant is deficient in nitrogen. Nitrogen fertilizer should be used as the main fertilizer, and phosphorus and potassium fertilizer should be sprayed together. When the tree is growing too vigorously, the leaves are big and tender, and the internodes are too long, the nitrogen is too rich, and the spray fertilizer should be mainly phosphorus and potassium fertilizer.
3. Give full play to fertilizer efficiency
Certain fertilizers such as phosphorus, iron, manganese, copper, zinc fertilizers, etc., if applied as roots, are easily fixed by the soil and affect the application effect. However, foliar spraying will not be restricted by soil conditions.
For another example, some fruit trees and other deep-rooted crops have relatively little absorption of certain nutrients. If traditional fertilization methods are used, it is difficult to apply to the root absorption site and cannot exert its fertilizer effect. However, foliar spraying can achieve better results. .
Various trace elements are essential nutrients in the process of crop growth and development, but the application amount is very small, such as molybdenum fertilizer, which is only a few grams per acre, and it is not easy to apply evenly if it is applied by root.
Only by foliar spraying can it be economically effective. According to research calculations, general crops sprayed with boron fertilizer on the foliar surface, the utilization rate of boron is more than 8 times that of base application. From the perspective of economic benefits, foliar spray is more cost-effective than root spray.
5. Reduce soil pollution
Applying a large amount of nitrogen fertilizer to the soil is easy to cause the accumulation of nitrate in groundwater and vegetables, which is harmful to human health. About 75% of the nitrate absorbed by humans comes from vegetables. If the method of foliar fertilization is adopted, the amount of soil fertilization can be appropriately reduced, which can reduce the nitrate content in plants and the residual mineral nitrogen in the soil.
What are the misunderstandings of foliar fertilizer application?
1. It can be sprayed as long as "Hua De Kai"
When spraying fertilizers on crops and vegetables, some farmers like to apply several types of foliar fertilizers together, thinking that the more types the better the effect, many farmers think that no matter what kind of fertilizer, as long as it is "dissolved", it can be used as leaf fertilizer. Spraying surface fertilizer is not the case. For example, highly volatile fertilizers such as ammonia, ammonium bicarbonate, etc., if sprayed as a foliar fertilizer, the high temperature after spraying will cause damage to the crop and burn the leaves, so it cannot be used as a foliar fertilizer. Moreover, many micro-fertilizers cannot be mixed with pesticides. Acidic fertilizers and alkaline fertilizers cannot be mixed and sprayed. The fertilizer-fertilizer, fertilizer-medicine mixed application should be carried out in a targeted manner to achieve "one spray, multiple effects" The role of this, otherwise it will be counterproductive.
2. The higher the spray concentration, the better
Some farmers believe that the greater the concentration of the foliar spray solution, the better, which is incorrect. For example, high-nitrogen water-soluble fertilizer should only be less than 1%, and potassium dihydrogen phosphate should only be less than 1%. More medium and trace element fertilizers such as sugar alcohol calcium fertilizer, sugar alcohol calcium boron fertilizer, sugar alcohol zinc, chelate Iron, chelated copper, etc. should only be controlled below 0.2%.
If the concentration is too high, not only will it fail to spray fertilizer, but on the contrary, it will cause dehydration and wilting of crop leaves, leading to fertilizer damage, which is similar to phytotoxicity and poisoning. Generally, spray the fertilizer on the front and back sides of the leaves and start dripping. Too much fertilizer liquid will lead to increased costs and waste of fertilizer.
3. It can be sprayed in all periods
Some farmers can't catch the key spraying period when spraying fertilizer on the leaves, so they can't achieve the predetermined effect. Some farmers believe that foliar sprays can be applied at all stages of plant growth and development, but this is not true. Foliar spraying should be carried out during the transition period of crop growth as far as possible, with at least 20 days interval between each spraying, and spraying 2-3 times for each season.
Different plants and different fertilizers have different suitable periods for spraying fertilizer on the leaves. Rice, corn, wheat and other cereal crops should be sprayed with fertilizer during booting, blooming, and filling period. Soybeans, peanuts, broad beans, kidney beans and other legumes should be sprayed with fertilizer during the flowering and pod-setting periods. Cotton should be sprayed with fertilizer during the flowering and boll period. Molybdenum fertilizer should be sprayed before the plants bloom. Boron fertilizers and zinc fertilizers have better effects when spraying plants at the initial flowering stage. From the point of time of spraying fertilizer, it should be in the morning on a cloudy or sunny day with no wind, after the leaves are exposed and dry, avoid the hot sun and high temperature periods, and the effect of spraying in the morning and evening is good.