过去研究结果证明:水稻土有利于异养型固氮微生物的活动,这在水田经济用氮具有重要意义。水田施用的稻草、稻根或共它含碳物质都能激发固氮作用,但关于无机态氮素在水稻土中对于固氮酶活性激发与抑制的临界浓度问题,还了解得不够。本试验是将铵态氮施用在 Past research results show that paddy soil is beneficial to the activities of heterotrophic nitrogen-fixing microorganisms, which is of great significance in economic use of nitrogen in paddy fields. Paddy rice, rice roots or a total of its carbon-containing substances can stimulate nitrogen fixation. However, the critical concentration of inorganic nitrogen on the activation and inhibition of nitrogenase activity in paddy soil is poorly understood. This test is to apply ammonium nitrogen