轮作制度对水稻生长季节稻田氧化亚氮排放的影响

通过盆栽试验(3次重复)，研究了3种主要轮作制度对稻田水稻生长季节N₂O排放的影响。结果表明，在水稻-小麦轮作中，水稻生长季节稻田N₂O-N的排放量为4．2kg·hm^-2，显著大于双季稻-小麦轮作中早稻的排放量2．2kg·hm^-2；但两者的季节平均排放通量无明显差异，分别为117和118μg·m^-2·h^-1。同时，两者都显著大于双季稻-小麦中的晚稻和持续淹水体系中的水稻生长季节稻田N20的平均排放通量，分别为67．0和42．1μg·m^-2·h^-1，在前作为旱作小麦的2种水稻生长季节中，大于91％的稻田N2O排放量都集中在水稻生长前半期；在前作为水稻的晚稻生长季节中，稻田N₂O排放量的91％集中在中期烤田及收获前水分落干阶段，轮作制度和前作水分状况极大地影响稻田N2O的排放。

Effects of cropping systems on nitrous oxide emissions from paddy soils during the rice-growing season

Cropping systems influence nitrous oxide (N2O) emissions from agricultural soils. Effects of 3 rice-based cropping systems on N2O emissions from paddy soils in pot experiment were investigated with closed chambers in triplicate. The results demonstrated that the seasonal N2O emission rate of the rice pot under rice-wheat cropping system was obviously higher than that of the early rice pot under double rice-wheat system, being 4.21 and 2.17 kg.hm-2, respectively. No distinct difference was observed between the seasonal average fluxes, which were 116.9 and 117.6 micrograms.m-2.h-1 respectively. Both of above mentioned seasonal average fluxes were greatly higher than that of the late rice pot under early rice-late rice-wheat cropping system and of rice pot under rice-flooding fallow system, being 67.0 and 42.1 micrograms.m-2.h-1 respectively. More than 91% of the seasonal emission was focused on the first half growing period both in the rice season in rice-wheat system and in the early rice season in double rice-wheat system in which the previous cropping was upland wheat. 91% of the seasonal emission was focused on the water drainage period including the mid-season aeration and final drainage in the late rice season in double rice-wheat system in which the previous cropping was lowland rice. The results implied that cropping system and water status of previous cropping impacted N2O emission from paddy soil.