Effects of nano-selenium on greenhouse gas emissions during composting: Insights into microbial subcommunities of different richness

Abstract

Nano-selenium, which has low toxicity and high biological activity, has become an important source of plant selenium supplementation. In this study, four groups, namely, CK, Se_L, Se_M and Se_H with nano-selenium levels of 0 μg/kg, 75 μg/kg, 150 μg/kg and 300 μg/kg (based on wet weight), respectively, were established to investigate the effects of nano-selenium on greenhouse gas emissions. The results found that the Se_M group had the highest fermentation temperature and the lowest greenhouse gas emission rate of the four groups. Compared with those in the CK group, cumulative emissions of carbon dioxide, methane and nitrous oxide in the Se_M group decreased by 13.69 %, 19.43 % and 46.32 %, respectively. Levels of the five most abundant genera in the rare subcommunity were significantly negatively correlated with the methane emission rate, whereas most bacterial genera in abundant and subdominant subcommunities were significantly positively correlated with gas emission rates. The addition of 75 μg/kg nano-selenium had a strong influence on the succession of the rare subcommunity, and promoted the growth and reproduction of the dominant genus Luteimonas. According to the above findings, nano-selenium at an appropriate concentration can reduce greenhouse gas emissions by regulating microbial communities. The production of nano-selenium organic fertilizer was conducive to the coordinated development of selenium-enriched and low-carbon agriculture.