稻麦轮作稻田中N_2O排放规律的研究

The N_2O Emission from Rice Fields under Rice-barley Rotation System

通过连续3年在中国浙江杭州的大型稻田原状土柱渗漏计中开展稻麦轮作稻田中N2O排放规律的研究,探讨了不同作物生长季节、不同年份、不同氮肥用量和氮肥品种对N2O排放的影响。结果表明：稻季的N2O排放主要发生在施肥之后,呈单高峰特征;麦季N2O排放则发生在施肥和较大降水之后,呈多高峰特征,麦季排放与降水有密切相关;不施氮情况下,稻田中N2O排放通量和累计排放量都是稻季高于麦季,稻季分别为麦季的1.97倍和1.34倍;施氮情况下,稻季与麦季排放通量和累计排放量则差别不大,排放通量是稻季略高于麦季（＋17%）,而累计排放量则是麦季略高于稻季（＋21.96%）.;施加氮肥可以促进N2O的排放;尿素的排放因子大于硫铵;在麦季施N100~1000 kghm-2的条件下,尿素的排放因子值为0.75~1.31,硫铵为0.15~0.16;在稻季施N150~300 kg hm-2的条件下,硫铵的排放因子值为0.19~0.20;在中国浙江省杭州稻麦轮作稻田中,N2O本底排放量为0.12~0.25 kgN2O-Nhm-2 yr-1,施肥引起的N2O排放占总排放的33%~59%。渗漏水中的N2O/NO3比值随种植季数而增高,可用乘幂关系式表达。

The N2O emission in rice-barley growing rice fields was conducted at the large monolith lysimeters in rice fields to explore the effects of different crop seasons,fertilizer managements,N fertilizer types and precipitation on the N2O emission from rice fields.The observations showed that abundant N2O emission could be found in the alternate stage of rice season to barley season,which was highly correlated with the precipitation during that stage.The emission flux from rice season was similar with that from barley season.To apply N fertilizer could promote obviously the N2O emission from rice fields.The emission factor for urea was higher than that of NH4（SO4）2 treatment.The ratio of N2O-N/NO3-N in percolating water increased with the increase of cropping seasons and the relationship of N2O-N/NO3-N in percolating water and NO3 in percolating water could be described by power formulas.