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

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

doi:10.3389/fmicb.2017.00409

Abstract

Manure composting is a significant source of atmospheric methane (CH4) and nitrous oxide (N2O) that are two potent greenhouse gases. The CH4 and N2O fluxes are mediated by methanogens and methanotrophs, nitrifying and denitrifying bacteria in composting manure, respectively, while these specific bacterial functional groups may interplay in CH4 and N2O emissions during manure composting. To test the hypothesis that bacterial functional gene abundances regulate greenhouse gas fluxes in windrow composting systems, CH4 and N2O fluxes were simultaneously measured using the chamber method, and molecular techniques were used to quantify the abundances of CH4-related functional genes (mcrA and pmoA genes) and N2O-related functional genes (amoA, narG, nirK, nirS, norB, and nosZ genes). The results indicate that changes in interacting physicochemical parameters in the pile shaped the dynamics of bacterial functional gene abundances. The CH4 and N2O fluxes were correlated with abundances of specific compositional genes in bacterial community. The stepwise regression statistics selected pile temperature, mcrA and NH4+ together as the best predictors for CH4 fluxes, and the model integrating nirK, nosZ with pmoA gene abundances can almost fully explain the dynamics of N2O 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 CH4 and N2O fluxes to elevated atmospheric CO2 concentration and rising temperature. Microbial abundances could be included as indicators in the current carbon and nitrogen biogeochemical models.

Highlights

It is of great concern worldwide that gaseous emissions from management of organic solid waste contribute to regional and global-scale environmental processes, such as eutrophication, acidification, and climate change (Naylor et al, 2005; Hou et al, 2015; Owen and Silver, 2015; Pardo et al, 2015)
Little is known about the interaction between pile physicochemical parameters and bacterial community, which has a key role in CH4 and N2O emissions from manure composting (Sharma et al, 2011; Angnes et al, 2013; Zhang et al, 2015)
The main objective of this study is to examine whether bacterial gene abundances can indicate dynamics of CH4 and N2O fluxes during windrow composting

Summary

Introduction

It is of great concern worldwide that gaseous emissions from management of organic solid waste contribute to regional and global-scale environmental processes, such as eutrophication, acidification, and climate change (Naylor et al, 2005; Hou et al, 2015; Owen and Silver, 2015; Pardo et al, 2015). The CH4 and N2O fluxes from manure composting have been studied extensively, contributing to a comprehensive assessment of CH4 and N2O emissions from manure composting worldwide [Czepiel et al, 1996; Hao et al, 2001; Intergovernmental Panel on Climate Change (IPCC), 2006; Xu et al, 2007; Mulbry and Ahn, 2014; Jiang et al, 2015; Pardo et al, 2015]. Few studies have simultaneously focused on quantitative analysis of bacterial community composition and CH4 and N2O fluxes from composting manure (Maeda et al, 2010a,b; Chen et al, 2014; Zhang et al, 2015). Comparative quantitative analysis of specific bacterial functional groups and their interplay in CH4 and N2O emissions during manure composting are still limited

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