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不同形态的氮肥,其氮素利用率是很不相同的。据估计,平均只有50%的氮被作物所吸收利用。根据大量的研究,氮素损失的原因主要是由于渗漏、反硝化,挥发和有机质的固定。土壤有效氮的瞬息变化,供氮与作物需氮之间的不相吻合对氮素的利用也产生不利的影响。施用长效肥可以解决这些问题。长效肥的优点在于能够连续不断而有规律的提供氮素。在长效肥中,美国TVA国家肥料发展中心研制的硫磺包膜尿素(SCU)是一种特别有希望的产品。本研究的目的是比较SCU和硫铵粒肥(AS)的氮素在土壤中的释放速率、硝化作用以及淋溶损失。供试土壤采自Valencia植柑地区。为了测定颗粒肥料中氮素释放速率
Different forms of nitrogen fertilizer, nitrogen utilization is very different. It is estimated that on average only 50% of the nitrogen is absorbed by the crop. According to a large number of studies, the causes of nitrogen loss are mainly due to leakage, denitrification, volatilization and fixation of organic matter. The transient changes in soil available N also have an adverse effect on the use of nitrogen in the disagreement between nitrogen supply and crop N demand. Applying a long-acting fertilizer can solve these problems. The advantage of a long-acting fertilizer is its ability to provide nitrogen continuously and regularly. Among the long-acting fertilizers, sulfur-coated urea (SCU) developed by the U.S. TVA National Fertilizer Development Center is a particularly promising product. The purpose of this study was to compare the release rate, nitrification and leaching loss of nitrogen from SCU and ammonium sulfate fertilizers (AS) in soils. The test soil was collected from Valencia Phragmites area. In order to determine the rate of nitrogen release from granular fertilizers