尿素和KNO3对水稻土无机氮转化过程和产物的影响Ⅱ.N2O生成过程

采用15N技术标记尿素和KNO3,研究了淹水条件下黄泥土和红壤性水稻土生成N2 O的主要过程。结果表明 ,黄泥土反硝化过程产物以N2 为主 ,N2 O的生成量可以略而不计。加入KNO3促进NO- 3异化还原成铵过程 ,从而增加N2 O生成速率。红壤性水稻土主要通过反硝化或好气反硝化过程生成N2 O ,随着土壤pH的提高或NO- 3 浓度升高 ,N2 O生成速率增大。无论是黄泥土还是红壤性水稻土 ,有相当一部分样本的N2 O的15N丰度在NO- 2 、NO- 3 、NH 4的15N丰度范围外 ,由此推论 ,氮转化生成N2 O的过程应在微生物细胞内进行。

EFFECTS OF UREA AND KNO3 ON PROCESSES AND PRODUCTS OF INORGANIC NITROGEN TRANSFORMATION IN PADDY SOILS Ⅱ. PROCESSES FOR N2O PRODUCTION

By using ¹⁵N techniques, effects of urea and KNO₃ on processes of N₂O production in Hydragric pad dy soil and Gleyic paddy soil, collected from Wuxi and Yingtan, respectively, were invest igated under flooding condit ions at 25.In the Hydragric paddy soil, N₂ was a predominated product of denitrification process.Addition of KNO₃ stimulated DNRA process and hence N₂O product ion.In the Gleyic paddy soil, N₂O was produced from denitrification and aerobic denitrification processes with its product ion rate increasing with soil pH and nitrate concentration.It was observed in some treatments of both the soils that the ¹⁵N abundance of N₂O was larger than those of all the inorganic nitrogen, NH₄⁺, NO₃^-, and NO₂^-, implying that the processes for N₂O production would take place inside cells of microbes.