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尿素(Co(NH_2)),从分子结构及化学反应过程来看,属于中性、有机态化肥;而且含氮多,肥效高,也是优良的氮素化肥。由于尿素优点多,人们比较喜欢使用,而且用的量多、面广;而用量过多,方法不当,往往效果较差。只有科学施用,才能取得最佳效果。尿素施用无度,会带来诸多不良后果。一是尿素为酰胺态氮肥,必须经过微生物活动转化为铵态氮肥,才能为作物根系吸收利用。过多的尿素会促使大量的微生物产生,剧烈活动;大量的、单一的微生物活动,必然消耗土壤中的有机质,放出多量的Co_2,这一过程导致土壤过度分散,造成土壤板结。比如我们随手甩一把尿素在地表,地表不是发泡,而是变硬、结壳,这就是过多的尿素破坏土壤结构的例证。二是尿素表施,因氧化作用强,助长了硝化过程,形成硝态氮肥——硝酸,此系酸性及生理酸性肥料,会使土壤的酸
Urea (Co (NH 2)), which belongs to neutral and organic fertilizers from the molecular structure and chemical reaction process, is also an excellent nitrogen fertilizer with high nitrogen and fertilizer efficiency. Due to the advantages of urea, people prefer to use, and the amount used, a wide range; and excessive use, improper methods, often less effective. Only scientific application, in order to achieve the best results. Urea application is not excessive, will bring a lot of adverse consequences. First, urea is an amide nitrogen fertilizer, which must be transformed into ammonium nitrogen fertilizer through microbial activities to absorb and utilize the crop roots. Too much urea can cause a large number of microorganisms to produce vigorous activities. A large number of single microbial activities will inevitably consume organic matter in the soil and release large amounts of Co 2. This process results in excessive soil dispersion and soil compaction. For example, we readily throw a urea on the surface, the surface is not foam, but harden, crusting, which is an example of excessive urea destruction of soil structure. Second, the urea table Shi, due to strong oxidation, contributed to the nitrification process, the formation of nitrate nitrate - nitric acid, the Department of acidic and physiological acid fertilizers, the soil acid