Urea is a high-quality, efficiency, and important nitrogen fertilizer. At the end of World War I, Germany had begun to applied urea as a fertilizer. Practice has proved that urea has high nitrogen content and has no sub-component. It has a good efficacy on increasing yield on all crops. After the 1950s, it had become the focus of the development of nitrogen fertilizers in different countries. During the 15 years between 1960 and 1975, the global urea production had increased by 10.5 times, and had gradually replaced the ammonium nitrate to become the world’s mostly applied nitrogen fertilizer since the 1970s. When applied into the soil, a small portion of urea is absorbed by plants in the form of amide, and the rest big portion is undergone ammoniation process to become ammonia by ammoniated urease, and then be absorbed by plants. Its decomposition rate depends on the the soil, temperature and water content; it generally lasts for 3 to 10 days, and making urea’s fertilizer efficacy longer than other kinds of fertilizer. Moreover, the loss of nitrogen content is relative mild. Urea is an ideal fertilizer of foliar application because it does not contain ingredients harmful to crops, and is neutral without burning the stem and leaves. It is hygroscopic and easy to penetrate into leaves together with water to be rapidly absorbed by crops. The concentration of foliar application is generally 0.5% to 2%. To improve the efficacy of urea utilization, besides correctly grasp the nature and application conditions, you should also pay attention to proper administration.
Urea is a neutral fertilizer without containing any harmful ingredients. It hydrolysis products, NH4+ and HCO3-can both be absorbed by crops. Continuous administration year after year generally causes no adverse effects on the nature of the soil. It is suitable for variety of crops and soil. Its efficacy is similar with that of ammonium sulfate containing equal content of nitrogen. It can be applied for deteriorated paddy fields which are easy to subject to hydrogen sulfide poisoning due to a lack of active iron and has a better effect than ammonium sulfate. Excessive application of urea or having very high biuret content is easy to cause ammonia and biuret poisoning; the higher the crops urease activity become, the higher sensitivity the crops will have to the urea and biuret poisoning.
Urea can be used as the feed supplements for ruminant animal. Industrial urea is the raw material for synthesizing urea-formaldehyde, melamine-formaldehyde resins. It is also used for the synthesis of some drugs such as tetracycline, Phenobarbital and caffeine. Dye industry also apply it to produce Vat Brown BR and phthalocyanine blue B.
Urea should be wrapped by plastic film inside and packaged by woven bag outside. It should be stored in dry warehouse and not allowed for mutual storage or shipment with acids.