覆草旱作稻田CH4和N2O的排放

通过田间试验比较水稻覆草旱作常规施氮肥、覆草旱作推荐施氮肥和常规水作水稻全生育期内稻田土壤微量气体的排放.结果表明,旱作稻田N2O排放总量比水作稻田高1.5~3.7倍,在旱作覆草处理中常规施肥N2O排放较推荐施肥高2.4倍.水作稻田CH4排放总量比旱作稻田多5~6倍,而两旱作处理间差异不显著.水作稻田CH4的排放与水稻生育期关系密切,以分蘖盛期的2.2mg/(m2h)为最大;旱作稻田CH4的排放与施氮关系不明显.施氮是影响旱作稻田N2O排放的关键因素,每次施氮后,旱作稻田均会出现剧烈的排放高峰.水稻不同栽培方式的增温潜势的高低顺序为:覆草旱作常规施氮肥>常规水作>覆草旱作推荐施氮肥.

The emission of CH4 and N20 in aerobic rice field mulched with straw

A field experiment was carried out in Yancheng to assess CH4 and N2O emission rate in different cultivation systems of rice. There were three treatments i.e. conventional N fertilization (I) and recommended N fertilization (II) both in aerobic cultivation mulched with straw, and conventional fertilization in paddy cultivation (III). During the whole growth season of rice, the total N2O fluxes in aerobic cultivation treatments was 1.5~3.7 times higher than in paddy cultivation and it was 2.4 times higher in (I) than in (II). Total CH4 flux in paddy cultivation was 5~6 times higher than in aerobic cultivation but there was no significant difference of CH4 flux between treatment (I) and (II). CH4 flux was closely related to the rice growth stages and the maximum emission rate of CH4 2.2mg/(m2h)] was found in the tillering stage of paddy rice. Fertilization significantly affected the N2O emissions in aerobic condition. A peak of the N2O emission was observed after every fertilization. In a 20-year time domain, the global warming potentials of the three treatments are in the order of (I) > (III ) > (II) based on the calculation of both N2O and CH4 emission in the different treatments.