不同土地利用方式土壤温室气体排放对碳氮添加的响应

揭示不同土地利用方式下土壤N2O产生机制及其CO2和CH4的排放，有助于土壤温室气体减排措施的制定。本研究以长沙金井河流域酸性红壤上菜地、稻田、茶园和林地土壤为研究对象，控制温度和土壤含水量，采用静态培养-气相色谱法，研究4种利用方式土壤N2O、CO2和CH4的排放对不同碳氮和硝化抑制剂添加的响应。结果表明，由于土壤pH较低，酸性红壤外加氮源后仅有较小的N2O排放。葡萄糖能够促进尿素添加后N2O的排放及土壤反硝化作用N2O的排放。异养硝化作用可能是酸性红壤N2O产生的主要途径。硝化抑制剂双氰胺（DCD）对酸性红壤N2O减排无明显效果。碳氮添加后土壤N2O的总排放量表现为茶园 > 菜地 > 稻田 > 林地。外源有机碳能够显著促进4种利用方式土壤CO2的排放，表现为茶园、稻田 > 菜地、林地。但除稻田土壤CH4排放增加外，菜地、茶园和林地土壤CH4排放对外源有机碳无明显响应。

Response of greenhouse gas emission to application of carbon and nitrogen in soils different in land use

Illustrating mechanisms of N2O generation in and emissions of CO2 and CH4 from the soil could help us design greenhouse gas mitigation strategies. An experiment was carried out in fields of acid red soil different in land use, i.e. vegetable garden, paddy field, tea garden and forest in Jinjing river region, Changsha, to study effects of application of carbon, nitrogen and nitrification inhibitor on N2O, CO2 and CH4 emissions under constant temperature and soil moisture, using the static incubation-gas chromatograph method. Results show that less N2O emission was observed from the acid red soil, low in pH, after application of N fertilizer; the addition of glucose stimulated N2O emission from the soil applied with urea and from soil denitrification. Heterotrophic nitrification might be the main pathway of N2O generation in acid red soil and nitrification inhibitor Dicyandiamide (DCD) had no significant effect on N2O reduction in the acid red soil. In terms of total N2O emission from the soil applied with N and C, the fields different in land use followed the the order of tea garden > vegetable garden > paddy field > forest land. Extraneous organic carbon could significantly stimulate soil CO2 emission from the four fields, showing an order of tea garden and paddy field > vegetable garden and forest land, but did not have mucheffect on CH4 emission in all the four fields except paddy field.