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硝化作用、反硝化作用和硝化细菌反硝化作用是土壤中产生N_2O的主要途径。以常用的冷季型草坪草早熟禾为对象,采用气体抑制剂培养法研究了不同施氮量对草坪土壤N_2O排放及其产生途径的影响。结果表明,对照草坪土壤的N_2O日排放量为7.2~8.2 g·m~(-2)·d~(-1),年施氮量10 g·m~(-2)未改变草坪土壤N_2O排放强度,年施氮量25、35 g·m~(-2)处理则分别比对照增加1.52倍和1.88倍,但二者之间没有显著差异。对照草坪土壤N_2O产生途径主要以异养硝化作用为主,其贡献率达65.7%,反硝化作用贡献率为34%,自养硝化和硝化细菌反硝化过程几乎不发生。年施氮量25 g·m~(-2)时,N_2O排放以硝化细菌反硝化、异养硝化和反硝化途径为主,贡献率分别为35%、35%和29%。年施氮量35 g·m~(-2)时,N_2O排放来自于4个途径,其中反硝化途径占41%,自养硝化途径贡献率增加至20%。
Nitrification, denitrification and nitrification bacteria denitrification are the main ways to produce N2O in soil. The cold-season turfgrass was used to study the effects of different nitrogen application rates on the N 2 O emission and its production in turf soils. The results showed that daily N_2O emissions of turfgrass were 7.2 ~ 8.2 g · m ~ (-2) d ~ (-1) and annual nitrogen application (10 gm -2) did not change the N_2O emission Compared with the control, 25 and 35 g · m -2 of nitrogen application increased 1.52 times and 1.88 times respectively, but there was no significant difference between them. Compared with turfgrass soil, the pathways of N_2O mainly dominated heterotrophic nitrification, with a contribution rate of 65.7% and a denitrification contribution rate of 34%. Allelopathic nitrification and denitrification of bacterial nitrification hardly occurred. Under the nitrogen application rate of 25 g · m -2, the N_2O emission was dominated by denitrification, heterotrophic nitrification and denitrification, with contribution rates of 35%, 35% and 29%, respectively. When the nitrogen application rate was 35 g · m -2, N 2 O emission came from 4 ways, of which denitrification was 41% and that of autotrophic nitrification was increased to 20%.