Acclimation of methane emissions from rice paddy fields to straw addition

Straw incorporation is a common long-term practice to improve soil fertility in croplands worldwide. However, straw amendments often increase methane (CH 4 ) emissions from rice paddies, one of the main sources of anthropogenic CH 4 . Intergovernmental Panel on Climate Change (IPCC) methodologies to estimate CH 4 emissions from rice agriculture assume that the effect of straw addition remains constant over time. Here, we show through a series of experiments and meta-analysis that these CH 4 emissions acclimate. Effects of long-term (>5 years) straw application on CH 4 emissions were, on average, 48% lower than IPCC estimates. Long-term straw incorporation increased soil methanotrophic abundance and rice root size, suggesting an increase in CH 4 oxidation rates through improved O 2 transport into the rhizosphere. Our results suggest that recent model projections may have overestimated CH 4 emissions from rice agriculture and that CH 4 emission estimates can be improved by considering the duration of straw incorporation and other management practices.