晚稻根际土壤特性对CH4和N2O排放的影响

为进一步揭示水稻根际土壤特性对CH4和N2O排放的影响机理，采用静态暗箱/气相色谱法对晚稻不同品种的CH₄和N₂O排放通量进行了原位观测，并对CH₄和N₂O排放通量与水稻根际土壤特性的相关性进行了分析。结果表明：不同品种CH₄、N₂O季平均排放通量间存在差异，变化范围分别为9.27～14.57 mg/（m²·h）、7.16～15.28 μg/（m²·h）；CH₄排放通量与5 cm处土壤Eh值呈极显著负相关（p<0.01），与pH值呈显著正相关（p<0.05）；N2O排放通量与5 cm处土壤Eh呈负相关，但不显著，与pH值呈显著负相关（p<0.05）。CH₄排放通量与0～7、7～13、13～20处土壤溶液中CH4浓度均呈显著正相关（p<0.05），N₂O排放通量与7～13 cm处N₂O浓度呈显著正相关（p<0.05）；CH₄、N₂O排放通量与0～7、7～13、13～20 cm处土壤溶液pH值均呈显著负相关（p<0.05），CH₄排放通量与电导率呈极显著正相关（p<0.01），N₂O与电导率呈负相关，但不显著。因此，水稻根际土壤Eh、pH、电导率以及CH₄浓度是影响CH₄排放的重要因素，根际土壤pH与N₂O排放密切相关。

Effects of Late Rice Rhizospheric Soil Characteristics on CH4 and N2O Emission from Paddy Field

An,one-year field experiment was conducted to measure in situ the greenhouse gases emission fluxes of the late rice cultivars in Hunan double-cropping rice areas and the correlation between the greenhouse gases emission and the characteristics of rice rhizospheric soil was studied to probe the effect of rice rhizospheric soil characteristics on methane and nitrous oxide emission by the method of static opaque chamber / modified gas chromatography.The results showed that the seasonal average emission fluxes of CH4 and N2O were different among rice cultivars,and their variation ranges were from 9.27 to 14.57 mg/(m2/h)and from 7.16 to 15.28 μg/(m2/h),respectively.CH4 emission fluxes were significantly negatively correlated with the Eh of 5cm depth soil(p<0.01),and were significantly positively correlated with the 5cm depth soil pH values(p<0.05).The negative correlation was not significant between N2O emission flux and 5cm soil Eh,however,the significantly negative correlation existed between the N2O emission flux and the pH values of 5cm depth soil(p<0.05).At the late rice growth stages,CH4 emission fluxes were significantly positive correlation with the CH4 contents of 0~7 cm,7~13 cm and 13~20 cm depth soil solution(p<0.05),and the N2O emission fluxes were significantly positive correlation with the N2O content of 7~13 cm depth soil(p<0.05).In addition,there were significantly negative correlation among CH4,N2O emission fluxes and the pH of 0~7 cm,7~13 cm,13~20 cm depth soil(p<0.05),and CH4 emission fluxes were significantly positive correlation with the conductivity of 0~7 cm,7~13 cm,13~20 cm depth soil solution(p<0.01),but the negative correlations were not significant between N2O emission fluxes and the conductivity of soil solution.Therefore,Eh,pH,conductivity and CH4,content of rice rhizosphere soil solution were the key factors that influenced CH4 emission from the paddy soil,and the rhizospheric soil pH was closely related with N2O emission.