巢湖圩区再生稻田甲烷及氧化亚氮的排放规律研究

为明确巢湖圩区再生稻田甲烷(CH_4)及氧化亚氮(N_2O)的排放规律,采用静态箱-气相色谱法对比观测了巢湖圩区2019—2020年再生稻田(RR)和稻麦轮作田(SW)的CH_4和N_2O排放通量,测定了土壤氧化还原电位(Eh)、土壤溶解性有机碳(DOC)、土壤铵态氮(NH_4~+-N)和硝态氮(NO_3~--N)。研究结果表明:SW处理在水稻返青期和分蘖期出现较大CH_4排放峰,RR处理的CH_4排放峰不仅出现在中稻季返青期和分蘖期,还出现在成熟期和再生季前期。SW处理N_2O排放峰主要出现在麦季降雨之后、稻季烤田及排水落干时,而RR处理N_2O排放峰主要出现在促苗肥施用后。与SW处理相比,RR处理的全年CH_4排放量、N_2O排放量、总温室气体排放量(TGHG)和温室气体排放强度(GHGI)分别降低了22.3%、86.5%、36.3%和15.9%(P0.05)。RR处理无小麦产量,但水稻产量增加了16.2%(P0.05)。稻季CH_4排放通量与土壤Eh呈显著负相关(P0.01),但与土壤DOC含量无显著相关性(P0.05)。RR处理的稻季N_2O排放通量与土壤NH_4~+-N浓度呈显著正相关(P0.05)。综合来看,在巢湖圩区种植再生稻不仅能提高水稻产量,还大幅减少总温室气体排放量和温室气体排放强度。

Reduced methane and nitrous oxide emissions from ratoon rice paddy in Chaohu polder area, China

A field experiment was conducted from 2019 to 2020 to compare the differences in methane(CH₄) and nitrous oxide(N₂O) emissions between ratoon rice(RR) fields and rice-wheat rotation(SW) fields in Chaohu polder using the static chamber-gas chromatograph technique. CH₄ and N₂O fluxes from the RR and SW fields were observed, while the soil redox potential(Eh), soil dissolved organic carbon(DOC), soil ammonium(NH₄⁺-N), and soil nitrate(NO₃^--N) contents were determined during the rice-growing season. The study results revealed that larger CH₄ flux peaks appeared in the SW treatment during the rice greening and tillering stages. However, CH₄ flux peaks of the RR treatment appeared at the regreening and tilling stages in the main season, and at the ripening stage of the main season, and in the first half of the ratoon season. The N₂O flux peaks of the SW treatment primarily appeared after precipitation in the wheat season and during drainage periods, while N₂O flux peaks for the RR treatment mainly appeared after fertilizer application for bud promotion. Compared with SW, the annual total CH₄ emissions, total N₂O emissions, total greenhouse gas emissions, and greenhouse gas emission intensities of RR were reduced by 22.3%, 86.5%, 36.3%, and 15.9%, respectively(P<0.05). No wheat grain was produced in the RR treatment, and rice yield increased by 16.2%(P<0.05). The seasonal variation in CH₄ flux during the rice-growing season for each treatment was significantly negatively correlated with soil Eh(P<0.01), but no significant correlation was found between CH₄ flux and soil DOC concentration(P>0.05). The seasonal variation of N₂O flux for RR treatment during the rice-growing season was significantly positively correlated with soil NH₄⁺-N content(P<0.05). In conclusion, planting ratooning rice in the Chaohu polder area increases rice yield and dramatically reduces the comprehensive greenhouse effect and greenhouse gas emission intensity.