Influence of Peat and Biochar on Gas Emissions and Microbial Metabolism During Co-composting of Chicken Manure and Maize Straw

This study investigated the effects of peat (PT) and maize straw biochar (MSB) on gas emissions and microbial metabolism characteristics during chicken manure (CM) and maize straw (MS) composting. Three treatments with different additives (0%, 5% PT, 5% MSB added on dry weight basis) were designed to conduct 30-day aerobic composting experiments in nine insulated polyvinyl chloride (PVC) reactors. The results showed that PT and MSB addition increased the temperature and nitrate-nitrogen (NO3--N) content but decreased the ammonium nitrogen (NH4+-N) content of compost. Compared with control, the total emissions of methane (CH4), nitrous oxide (N2O) and ammonia (NH3) in PT and MSB were reduced by 20.13-30.57%, 28.88-47.46% and 37.35-52.71%, respectively. In addition, PT and MSB amendments improved the microbial utilization capacity on carbohydrates, esters and carboxylic acids. Redundancy analysis revealed that temperature, NH4+-N, pH and microbial metabolism were positively correlated with CH4, N2O and NH3 emissions. Meanwhile, temperature, NH4+-N and pH also had positive correlations with microbial metabolism. Together these results indicated that PT and MSB amendment improved the metabolism capacity of microbes and reduced CH4, N2O and NH3 emissions, eventually mitigating nitrogen loss and promoting the quality of compost product. [GRAPHICS] .