Methane production and methanogenic archaeal communities in two types of paddy soil amended with different amounts of rice straw

Soil type and returning straw to the field are the important factors that regulate CH₄ formation in paddy soil, and the variations of biogeochemical parameters and methanogens communities play important roles in the formation of CH₄. In the present study, two paddy soil types [silt loam soil (JX) and silty clay loam soil (GD)] with different amounts of rice straw additions were incubated under anaerobic conditions to investigate the relationship between CH₄ production, biogeochemical variations, and methanogenic archaeal communities. Straw incorporation significantly stimulated CH₄ production in two soil types. CH₄ production in JX soil was higher than the GD soil with equal straw addition. Significant differences between biogeochemical parameters and methanogenic archaeal communities were observed between two soil types. Straw addition increased archaeal 16S rRNA genes and mcrA genes copy numbers, especially in JX soil. Multiple regression analysis indicated that variations in H₂, sulfate, Fe (II) concentrations, archaeal 16S rRNA genes and mcrA genes copy numbers, methanogens diversity index, and the relative abundance of Methanosarcinaceae and Methanobacteriaceae together influenced CH₄ production in two soil types. These results indicated that methane production was influenced by the comprehensive effects of biotic and abiotic factors in paddy soils.