Straw application in paddy soil enhances methane production also from other carbon sources

[摘要] Flooded rice fields are an important source of the greenhouse gas methane.Methane is produced from rice straw (RS), soil organic matter (SOM), andrice root organic carbon (ROC). Addition of RS is widely used forameliorating soil fertility. However, this practice provides additionalsubstrate for CH₄ production and results in increased CH₄emission. Here, we found that decomposing RS is not only a substrate ofCH₄ production, but in addition stimulates CH₄ production fromSOM and ROC. Apart from accelerating the creation of reduced conditions inthe soil environment, RS decomposition resulted in enhancement ofSOM-derived CH₄ production. In particular, hydrogenotrophicmethanogenesis from SOM-derived CO₂ was stimulated, presumably byH₂ released from RS decomposition. On the other hand, the enhancementof ROC-derived CH₄ production after RS application was probably causedby the significant increase of the abundance of methanogenic Archaea in theRS treatment compared with the untreated control. Our results show thattraditional management of rice residues exerts a positive feedback onCH₄ production from rice fields, thus exacerbating its effect on theglobal CH₄ budget.

[学科分类] 地球化学与岩石