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一、前言 施入水田中的NH_4~+态氮肥,在土壤表面(氧化层)经硝化细菌的作用,氧化成NO_3~-,随水淋至耕层下部的还原层,在嫌氧条件下,经反硝化作用还原成N_2而挥发。Broeshart(1971)综合六个国家的联合试验,指出水田土壤中氮的气态损失为17～19％(氮肥深施处理为7～19％)。郭智芬等在湖北省试验条件下研究证明尿素氮的损失量为20～30％,碳铵氮的损失量为40％左右。可见,氮肥的损失是很大的。为防止或减少这种损失,曾提出铵态氮深施(施于还原层)的措施,在这里,NH_4~+被土壤胶体吸附在原位,减少了淋失,同时也避免了硝化作用,因而也不会有反硝化的挥发损失,减少氮素挥失的另一种办法,是在施用氮肥的同时,施用硝化抑制剂,抑制了硝化作用,也就堵塞了反硝化挥失的进程。
I. INTRODUCTION NH_4 ~ + applied nitrogen fertilizer in paddy field is oxidized to NO_3 ~ - by the action of nitrifying bacteria on the soil surface (oxide layer) After denitrification reduced to N_2 and volatile. Broeshart (1971) conducted a joint study of six countries, pointing out that the loss of nitrogen from paddy soils was 17-19% (7-19% for deep fertilization). Guoxi Fen and other research conditions in Hubei Province proved that the loss of urea nitrogen is 20 to 30%, the loss of ammonium bicarbonate is about 40%. Can be seen that the loss of nitrogen is great. In order to prevent or reduce this kind of loss, the measures of deep application of ammonium nitrogen (applied to the reduction layer) have been put forward. Here, NH4 + is adsorbed by soil colloids in situ, reducing the leaching and avoiding nitrification. Therefore, there will be no denitrification volatilization loss. Another way to reduce the loss of nitrogen is to use nitrification while applying nitrification inhibitors to inhibit the nitrification, thus blocking the process of denitrification and volatilization.