一、氮肥的发展情况回顾过去二十几年(1950—1972年)以来,世界上化学氮肥的发展情况,其消费量从400万顿增加到3200万顿(单位N),增加了8倍(见附表)。在氮肥品种方面,尿素和液氨的产量不断增加,特别在最近十年内,增加得最快,而硫铵、氯铵的产量却迅速下降,石灰氮、硝酸钙等肥料品种已不居重要地位。总的趋势是氮肥向浓缩的方向发展。硝铵由于 I. Development of Nitrogen Fertilizer Recalling the development of chemical nitrogen fertilizer in the world over the past two decades (1950-1972), its consumption increased from 4 million tons to 32 million tons (in N), an increase of 8 times ( See Schedule). In terms of nitrogenous fertilizers, the output of urea and liquid ammonia continuously increased, especially in the last ten years, while the output of ammonium sulfate and ammonium chloride decreased rapidly. Fertilizer species such as lime nitrogen and calcium nitrate did not occupy an important position . The general trend is to nitrogen fertilizer to the direction of enrichment. Ammonium nitrate due