Soil texture drives rice methane emissions at tillering stage via carbon fractions, nutrients and microbial abundance

This study explored the complex mechanisms of methane (CH₄) emissions in paddy fields, focusing on the often-overlooked role of soil texture. Through the analysis of 31 paddy soil samples, the research investigated the complex interactions among soil texture, organic carbon composition, soil nutrients, and microbial abundance in regulating CH₄ emissions during the tillering stage of rice. The results revealed significant variations in CH₄ emissions among different soils, which were notably associated with soil texture, organic carbon, nutrients levels, and microbial abundance. Soil texture, particularly clay content, emerged as a key factor influencing the composition of organic carbon, showing a significant positive correlation with mineral-associated organic carbon (MAOC). While organic carbon components significantly enhanced CH₄ emissions, their effects were not uniform: particulate organic carbon correlated negatively with emissions, whereas MAOC showed a positive association. Soil texture also influenced nutrients availability, with clay content significantly correlated with soil nitrogen and phosphorus content, which in turn affects the abundance of functional genes. Specifically, mcrA abundance was positively correlated with available potassium, while pmoA abundance was positively correlated with available phosphorus. Additionally, dissolved organic carbon promoted pmoA abundance, although this effect was mitigated by higher clay content. Network analysis further emphasized the central role of soil texture, with clay exhibiting the highest degree and closeness centrality. In conclusion, soil texture is a fundamental and core factor influencing CH₄ emissions at tillering of rice, exerting its influence through multiple pathways including modulating the composition of organic carbon, nutrient availability, and the abundance of methanogens and methanotrophs. These findings provide theoretical foundations for developing low-carbon cultivation strategies tailored to different soil textural characteristics.