Six misunderstandings of foliar spraying of crops

According to the analysis of statistical data, foliar fertilizer spraying on crops on moderately fertile soil can increase the yield of crops by 5%, fruit trees and vegetables by 5%, 15% and 20%, respectively. However, in some places, due to incorrect understanding or improper application, the effect of increasing production is not good, and even into a misunderstanding, which is worthy of attention. Spraying foliar fertilizer in any growth period of crops when the leaf area of crops is as large as possible, by means of foliar spraying, the leaves can intercept as much fertilizer as possible and achieve the best effect, otherwise a large amount of fertilizer can not touch the leaves, it will never play the role of foliar fertilizer spraying. Therefore, foliar fertilizer spraying should generally be carried out in the middle and later stages of crop growth in order to get the maximum benefit. If the fruit trees are often sprayed with phosphorus and potassium fertilizer in the late growth stage, the yield of fruit trees can be increased. For fruit trees with calcium deficiency in the later stage, 0.3% calcium nitrate solution should be sprayed 40-50 days before fruit harvest, with an interval of one week for 3-4 times, which can effectively correct the bean spot disease caused by calcium deficiency in apples and improve fruit quality. No matter what kind of fertilizer can be used as foliar spraying fertilizer, many farmers think that any fertilizer can be used as foliar spraying fertilizer, but it is not. Some highly volatile fertilizers, such as ammonia and ammonium bicarbonate, will volatilize ammonia after spraying, causing fumigation to crops. The other is that fertilizer such as potassium chloride, which is taboo to some crops, should not be sprayed on taboo crops such as tobacco. Foliar fertilizer can be sprayed at any time. Some people think that foliar fertilizer can be sprayed at any time, which is wrong. If there are drops of water or dew on the leaves after rain or early in the morning, it is not suitable to spray fertilizer, otherwise the concentration of fertilizer spraying will be reduced and can not meet the concentration requirements. Fertilizer spraying should not be applied to crops during flowering, such as rice, corn, wheat, rape, soybean and other crops, foliar fertilizer spraying will affect their flowering, pollen emission and pollen fertilization and so on. Under the condition of strong light, foliar fertilizer can not be sprayed in the hot sun at noon on a sunny day, because it can not maintain the moist state for a long time after spraying, the leaf absorption condition is poor, and the utilization rate is greatly reduced. Therefore, foliar fertilizer spraying is best to choose a windless cloudy day or sunny day from 9 am to 10:00, and after 4 pm. If it rains 3 hours after spraying, make up for spraying again when it is clear, but the concentration should be reduced appropriately. The higher the concentration, the better. Some people think that the effect of increasing the concentration a little bit will be more obvious, which is incorrect. Foliar fertilization only plays a supplementary and regulatory role, and can not replace soil fertilization. The concentration of fertilizer should be strictly controlled. In the range of suitable use, the concentration of spraying should be low but not high. However, different crops have different fertility tolerance and different requirements; different kinds of fertilizers and different concentrations of fertilizer are sprayed. Too low concentration can not achieve the effect of fertilizer spraying; too high concentration will often dehydrate the leaves and cause fertilizer damage, which is one of the keys to the success or failure of foliar fertilizer spraying. For example, urea is used as foliar fertilizer, the concentration is generally 0.5% Mel 2%; calcium superphosphate is 1% Mel 5%; potassium dihydrogen phosphate is 0.2% Mel 0.5%; Boric acid is 0.1% Mel 0.5%; ammonium molybdate is 0.02% Mel 0.05%; Zinc Sulfate is 0.05% Mel 0.2%. At the same time, it is necessary to grasp that the concentration of spraying at the seedling stage should be appropriately lower; the concentration of spraying in the middle and later stages of growth should be appropriately higher; when crops grow normally, the concentration should be lower, and the concentration of trace element fertilizer should be lower; the concentration of major element fertilizer should be higher; the concentration of dicotyledon spraying should be lower; and the concentration of Monocotyledon spraying should be appropriately higher. When spraying fertilizer at will, we always think that the mixed application of many kinds of fertilizers can achieve better results and save labor. In fact, not all kinds of fertilizers can be mixed and sprayed. The correct method is to spray fertilizer-fertilizer or fertilizer-medicine mixture pertinently, which can get the effect of "one spray, multiple effects". But a lot of micro-fertilizers can not be mixed with pesticides, acidic fertilizers can not be mixed with alkaline fertilizers, generally for the sake of caution, a small amount of fertilizer and medicine can be mixed into the same vessel before mixing, and after a certain period of time, if there is no turbidity, precipitation, bubbles and other phenomena, it can be mixed, and attention should also be paid to the change of the pH of the solution after mixing. In general, when the pH value is about 7, it is beneficial to the absorption of leaves. The common misunderstanding of increasing the number of spraying is that the more times of foliar spraying, the better. The crops with short growth period are generally sprayed 1-2 times, and those with long growth period can be sprayed 2-3 times. It can also be sprayed 1-2 times according to the soil fertility of the seedlings. It should be sprayed continuously in the same growth period with an interval of about 10 days each time. Spray trace element fertilizer, spray once, need to spray the second time, the interval is longer. Spraying too much fertilizer liquid will lead to an increase in cost and a waste of fertilizer.