AUTHOR=Li Shuqing , Song Lina , Gao Xiang , Jin Yaguo , Liu Shuwei , Shen Qirong , Zou Jianwen 

TITLE=Microbial Abundances Predict Methane and Nitrous Oxide Fluxes from a Windrow Composting System

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00409

DOI=10.3389/fmicb.2017.00409

ISSN=1664-302X

ABSTRACT=<p>Manure composting is a significant source of atmospheric methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) that are two potent greenhouse gases. The CH<sub>4</sub> and N<sub>2</sub>O fluxes are mediated by methanogens and methanotrophs, nitrifying and denitrifying bacteria in composting manure, respectively, while these specific bacterial functional groups may interplay in CH<sub>4</sub> and N<sub>2</sub>O emissions during manure composting. To test the hypothesis that bacterial functional gene abundances regulate greenhouse gas fluxes in windrow composting systems, CH<sub>4</sub> and N<sub>2</sub>O fluxes were simultaneously measured using the chamber method, and molecular techniques were used to quantify the abundances of CH<sub>4</sub>-related functional genes (<italic>mcrA</italic> and <italic>pmoA</italic> genes) and N<sub>2</sub>O-related functional genes (<italic>amoA</italic>, <italic>narG</italic>, <italic>nirK</italic>, <italic>nirS</italic>, <italic>norB</italic>, and <italic>nosZ</italic> genes). The results indicate that changes in interacting physicochemical parameters in the pile shaped the dynamics of bacterial functional gene abundances. The CH<sub>4</sub> and N<sub>2</sub>O fluxes were correlated with abundances of specific compositional genes in bacterial community. The stepwise regression statistics selected pile temperature, <italic>mcrA</italic> and NH<sub>4</sub><sup>+</sup> together as the best predictors for CH<sub>4</sub> fluxes, and the model integrating <italic>nirK</italic>, <italic>nosZ</italic> with <italic>pmoA</italic> gene abundances can almost fully explain the dynamics of N<sub>2</sub>O fluxes over windrow composting. The simulated models were tested against measurements in paddy rice cropping systems, indicating that the models can also be applicable to predicting the response of CH<sub>4</sub> and N<sub>2</sub>O fluxes to elevated atmospheric CO<sub>2</sub> concentration and rising temperature. Microbial abundances could be included as indicators in the current carbon and nitrogen biogeochemical models.</p>