稻油不同轮作模式对农田甲烷和氧化亚氮排放的影响

以南方稻区不同轮作模式为研究对象，采用静态箱-气相色谱法研究水稻-油菜轮作处理的甲烷（CH₄）和氧化亚氮（N₂O）排放特征，并估算稻田增温潜势（GWP）和温室气体排放强度（GHGI）.结果表明，双季稻田、一季中（晚）稻田、油菜地和休闲地CH₄平均排放量分别为135.25，55.64、5.05和1.89 kg ·hm^-2，稻季CH₄排放占不同轮作周年CH₄排放的91.8%~98.5%，稻田土壤水溶性有机碳与CH₄排放呈显著正相关，常规晚稻稻田CH₄排放比杂交晚稻高18.7%（P<0.05）；双季稻田、一季中（晚）稻田、油菜地和休闲地N₂O平均排放量分别为0.94、0.64、1.38和0.24 kg ·hm^-2，油菜地的N₂O排放占周年排放的57.2%~70.2%，双季稻和一季稻处理的冬闲农田N₂O排放占周年排放的17.8%和30.6%，杂交稻和常规稻稻田N₂O排放无显著性差异；双季稻-冬闲和双季稻-油菜的GWP处理高于稻-油和稻-冬闲处理，稻季排放CH₄的GWP占轮作周年GWP排放的71.2%~90.9%；GHGI以稻-稻-油菜最高，稻-油和稻-冬闲处理较低，综合环境效益和经济效益，建议南方稻区选择杂交晚稻-油菜的种植模式，有利于南方多熟制稻田的温室气体减排.

Effects of Different Rotation Patterns of Oil-Rice on Methane and Nitrous Oxide Emissions in Rice Fields

A field experiment was carried out to investigate the effects of different rice-rape rotation systems on methane and nitrous oxide emissions, which were measured using the static chamber/gas chromatography method, prediction of their global warming potentials (GWP), and greenhouse gas intensity (GHGI) in paddy fields. The results showed that the average cumulative emissions of CH₄from a double cropping paddy field, single season rice field (including middle or late), rape field, and leisure land were 135.25, 55.64, 5.05, and 1.89 kg ·hm^-2, respectively. The CH₄ emission during the rice season accounted for 91.8%-98.5% of the annual CH₄ emission in different rotation years, and the contents of dissolved organic carbon in paddy soil exhibited a significantly positive correlation with CH₄ emission. The CH₄ emission in conventional late rice paddy was 18.7% higher than that of hybrid late rice paddy (P<0.05). The average cumulative emissions of N₂O from double cropping paddy field, single season rice field (including middle or late), rape field, and leisure land were 0.94, 0.64, 1.38, and 0.24 kg ·hm^-2, respectively. Out of the total annual N₂O emission, 57.2% to 70.2% was from the rape field; 17.8% and 30.6% was due to the winter fallow treatments with previous crop type of double corpping rice and single season rice, respectively. There was no significant difference in N₂O emission between hybrid rice and conventional rice paddy fields. The GWP of double cropping rice-winter fallow and double cropping rice-rape was higher than that of rice-rape and rice-winter fallow, and the GWP of CH₄ in rice season accounted for 71.2% to 90.9% of the annual GWP of rotation. The highest treatment of GHGI was rice-rice-rape, and the treatment of rice-oil and rice-winter slack was lower. According to the comprehensive environmental and economic benefits, the late hybrid rice-rape patterns should be selected to reduce greenhouse gases in multiple cropping rice fields of South China.