Why does urea contain biuret?What’s the downside?Clever application of urea can be avoided

2022-05-22 0 By

Urea is a kind of nitrogen fertilizer commonly used in our daily agricultural production. It has high concentration, fast fertilizer effect, soil application and foliar spraying, direct application, and can be used to produce a variety of compound fertilizer multi-purpose fertilizer.Urea in the soil does not remain harmful substances, the general long-term application of soil will not cause adverse effects.However, if improper application, the harm of urea can be many ha, mainly because of the cause of containing biuret.A, what is biuret, containing biuret urea and ordinary urea what is the difference between biuret is a strong permeability of the substance, also known as biuret, up to a certain content, will cause the dehydration of seed cells, the young roots of crops, sprouts have an inhibitory effect.No matter what urea, or urea as raw material production of compound fertilizer and other fertilizers, are more or less contain biuret this toxin.Urea in the granulation process, are generally dissolved by high temperature, when the temperature is too high, will produce a small amount of biuret, which is difficult to get rid of a substance.Can say so, all urea, contain biuret, whether containing biuret urea or ordinary urea, in the problem of containing biuret, can be said to be no difference, just how much content.Our country sets, in the urea used as fertilizer, the content of biuret should be less than 1.5%.Urea containing more than 0.5% should not be used as seed, seedling or foliar fertilizer.According to relevant regulations, urea packaging bags should be marked with biuret, pay attention to safe application.Two, clever application of urea to avoid harm urea is suitable for a variety of crops and a variety of soil, can be used as base fertilizer, topdressing and foliar fertilizer, but generally should not be used as fertilizer and seedling period fertilizer.First of all, urea itself has a certain toxicity, too much fertilization will burn seeds burn seedlings, affecting the germination of seeds and seedling growth.Secondly, urea contains a certain amount of biuret, the growth of seedling bud has an inhibitory effect.Third, urea decomposition in the soil, will produce a high concentration of ammonia, easy to grow seedlings.Application of urea to corn, wheat, rice and other cereal crops has a better yield increase effect.If you want to use urea as fertilizer, remember to plant fertilizer isolation, with an interval of about 3 per cent is better, can effectively prevent burning and burning seedlings.Urea is better than other nitrogenous fertilizers when used as foliar fertilizer.Foliar spraying urea, general crops can use 1%, seedling period is better with 0.5%.It is better to spray in the morning or evening.However, when urea is used for foliar fertilizer, the content of biuret in urea of this variety shall not exceed 0.5%, but because the biuret contained in some urea exceeds 0.5%, or sprayed with urea for many times, certain biuret is accumulated in the plant, because of biuret is not easy to decompose in the plant body, resulting in their poisoning.The symptom of biuret poisoning is that the leaf tip is yellowing, which is permanent and only new leaves do not show yellowing. When the area of yellowing is large, photosynthesis is affected.Potatoes, yellow tobacco and other sensitive to biuret, easy to poisoning victims, please be careful foliar application.Improper application of urea will cause nutrient loss, paddy field should pay attention to deep application, that is, 5 cm below the soil is better, dry land should also pay attention to deep tillage cover soil.The conversion time of urea in soil should be considered when applying urea as topdressing.Generally speaking, the transformation time of urea in soil is accelerated with the increase of temperature, that is, the fertilizer efficiency is faster when the temperature is high than when the temperature is low.Dry land is faster than paddy land, clay is faster than sandy soil, and acid soil is slower.And organic fertilizer with fast application.Because urea is an amide nitrogen fertilizer, it needs to be converted into ammonium nitrogen fertilizer in the soil before it can be absorbed by crops, so it has to be applied several days earlier than other nitrogen fertilizers so as not to delay the critical period of crop nutrition for fertilizer absorption.Urea as a base fertilizer, the general field crop 30-40 catty can be applied.In order to prevent the poisoning of urea and its transformation products and biuret, excessive amount or concentration of urea should not be applied.In short, no matter what kind of urea, due to high temperature granulation reasons, more or less contain biuret this substance, whether marked with biuret or not, biuret are in, whether urea containing biuret or ordinary urea.