Effects of fertilization on microbial abundance and emissions of greenhouse gases (CH (4) and N(2)O) in rice paddy fields

This study is to explore effects of nitrogen application and straw incorporation on abundance of relevant microbes and CH (4) and N(2)O fluxes in a midseason aerated rice paddy field. Fluxes of CH (4) and N(2)O were recorded, and abundance of relevant soil microbial functional genes was determined during rice‐growing season in a 6‐year‐long fertilization experiment field in China. Results indicate that application of urea significantly changed the functional microbial composition, while the influence of straw incorporation was not significant. Application of urea significantly decreased the gene abundances of archaeal amoA and mcrA, but it significantly increased the gene abundances of bacterial amoA. CH (4) emission was significantly increased by fresh straw incorporation. Incorporation of burnt straw tended to increase CH (4) emission, while the urea application had no obvious effect on CH (4) emission. N(2)O emission was significantly increased by urea application, while fresh or burnt straw incorporation tended to decrease N(2)O emission. The functional microbial composition did not change significantly over time, although the abundances of pmoA, archaeal amoA, nirS, and nosZ genes changed significantly. The change of CH (4) emission showed an inverse trend with the one of the N(2)O emissions over time. To some extent, the abundance of some functional genes in this study can explain CH (4) and N(2)O emissions. However, the correlation between CH (4) and N(2)O emissions and the abundance of related functional genes was not significant. Environmental factors, such as soil Eh, may be more related to CH (4) and N(2)O emissions.