长期施肥对双季稻田甲烷排放和关键功能微生物的影响

研究不同施肥措施对双季稻田甲烷(CH_4)排放特征的影响及其微生物学机理,对合理利用及评价不同施肥模式对水稻生长的影响具有重要意义。以长期施肥定位试验田为平台,采用静态箱-气相色谱法对施用化肥(MF:mineral fertilizer alone)、秸秆还田配施化肥(RF:rice residues plus mineral fertilizer)、30%有机肥配施70%化肥(LOM:30%organic matter plus 70%mineral fertilizer)、60%有机肥配施40%化肥(HOM:60%organic matter plus 40%mineral fertilizer)和无肥(CK:without fertilizer)条件下双季稻田CH_4排放及其微生物学机理进行了分析。结果表明,早稻和晚稻生长期,不同施肥处理稻田CH_4排放通量均显著高于CK,表现为HOMLOMRFMFCK。各处理间CH_4总排放量差异达显著水平,其大小顺序与排放通量趋势一致,以HOM处理为最高,比CK处理增加105.56%,其次是LOM和RF处理,分别比CK处理增加72.97%和54.17%。关键功能土壤微生物测定结果表明,早稻和晚稻各个主要生育时期,各处理稻田土壤产甲烷古菌的数量变化范围为(3.18—81.07)×10~3cfu/g,土壤甲烷氧化细菌的数量变化范围为(24.82—379.72)×10~3cfu/g。稻田土壤产甲烷古菌和甲烷氧化细菌数量大小顺序为HOMLOMRFMFCK,各施肥处理均显著高于CK;HOM、LOM、RF处理显著高于MF、CK处理。双季稻田CH_4排放与稻田土壤产甲烷古菌、甲烷氧化细菌数量变化关系密切。采用有机无机肥配施促进了双季稻田生态系统CH_4的排放和关键功能微生物的数量。

Effects of long-term fertilizer treatments on CH4 fluxes and key functional microorganisms in a double-cropping paddy field

Methane (CH₄) fluxes and their key functional microorganisms in a double-cropping paddy field are affected by long-term fertilizer treatment; thus, it was important to utilize and evaluate different fertilization regimes on rice growth. A manual static chamber-gas chromatography (GC) technique was used to verify the effects of different fertilizer treatments, which included mineral fertilizer alone (MF), rice residues plus mineral fertilizer (RF), 30% organic matter plus 70% mineral fertilizer (LOM), 60% organic matter plus 40% mineral fertilizer (HOM), and a control without fertilizer (CK), on CH₄ emissions from double-cropping paddy fields in subtropical regions of China and on the microbial mechanisms driving them. The results showed that the flux of CH₄ from the HOM, LOM, RF, and MF treatments was higher than that of the CK treatment, and it varied with different fertilizer treatments in the following order:HOM > LOM > RF > MF > CK. Further, CH₄ emissions were significantly greater during the entire growth period for early and late rice in the HOM, LOM, RF, and MF treatments than in the CK treatment (P < 0.05). CH₄ emissions from paddy fields in the HOM, LOM, and RF treatments increased by 105.56%, 72.97%, and 54.17%, respectively, compared with the CK treatment. At the main growth stages of early and late rice, the abundance of methanogens under the different fertilizer treatments ranged from 3.18×10³ cfu/g to 81.07×10³ cfu/g, while that of methanotrophs ranged from 24.82×10³ cfu/g to 379.72×10³ cfu/g. The results indicated that the abundance of the methanogens and methanotrophs were significantly greater in the HOM, LOM, RF, and MF treatments at the main growth stages of early and late rice than they were in the CK treatment. Additionally, the abundance of methanogens and methanotrophs varied under the different fertilizer treatments in the following order:HOM > LOM > RF > MF > CK. Moreover, the abundance of methanogens and methanotrophs was significantly greater in the HOM, LOM, and RF treatments at the main growth stages than they were in the MF or CK treatments. CH₄ emissions were significantly correlated with the abundance of methanogens and methanotrophs during the whole growth period. Our results clearly demonstrated that CH₄ emissions from paddy fields and the abundance of key functional microorganism were promoted by the application of inorganic fertilizer combined with organic manure practices in a double paddy field ecosystem.