Urea has the functions of regulating flowers, thinning flowers and fruits, preventing insects and making base fertilizer. Generally, spraying 0.5% urea solution can promote the growth of new shoots and inhibit the differentiation of flower buds. When the concentration is higher than 7.4%, it can play a role in thinning flowers and fruits At the same time, it can prevent and control aphids, red spiders, cabbage worms and other pests and promote plant growth.
Generally, you should choose sunny weather and apply it after 4 pm. It must be noted that the concentration must not be too large. We usually spray urea solution with a concentration of 0.2 to 0.5 on the leaves of fruit trees. When spraying, try to choose a sprayer with good atomization effect for spraying. Generally, this sprayer sprays evenly, focusing on the upper middle part of the blade and the rear part of the blade.
Use of urea
Urea is a kind of crop fertilizer that needs to be applied frequently. Its main function is not to leave any harmful substances in the soil, and it has no adverse effects after long-term application. Urea is synthesized directly from liquid ammonia and carbon dioxide at high temperature and high pressure. Urea can be used not only as chemical synthetic fertilizer, but also as a large number of raw materials for other chemical products, medicine, food, dye solvent, moisture absorbent, viscose fiber expansion agent, resin finishing agent, diesel engine tail gas treatment liquid and other products.
Vegetables can't be mixed with alkaline fertilizers. After urea is applied, it must be converted into ammonium nitrogen before it can be used by crops. Under alkaline conditions, most of the nitrogen in ammonium nitrogen will become ammonia and volatilize. Therefore, urea can not be mixed with plant ash, calcium magnesium phosphate, ammonium bicarbonate and other alkaline fertilizers or applied at the same time.