Temporal variation of the coupling relationship between methanogens and biogeochemical process in soil-microbes-rice system.

Abstract

Microbial community were most resilient option for methane associated mitigation strategies. Biogas slurry provides plant nutrition and affects microbial community. However, little is known about the changes of the functional guilds (methanogen and methanotroph) in the geochemical context after addition biogas slurry. For this purpose, a pot experiment was conducted. Six treatment groups were included in this study, four with biogas slurry: water ratio (1:4, T02; 2:3, T04; 3:2, T06; 4:1, T08), one with a chemical fertilizer (F), and a control (CK). The effective tiller and biomass significantly increased by 1.9 times and 2.1 times in T02 relative to CK. The relative abundance of Bacteroidetes in the biogas slurry treatments was 31.5%, while that in CK was 11.4%. The dominant methanogens in CK, F and treatments were different at heading and mature stages. CK and F were hydrogenotrophs with relative abundance of 0.09% and 0.06%, and the treatment group was acetotrophs with mean value of 1.21% at heading stage. Compared with CK, the number of methanotrophs in the treatments at heading stage increased by 4.1 times, while that at mature increased by 10.3 times. The methanogenic community in the treatments may be shaped by the amount of biogas slurry applied rather than by biogeochemical processes at heading stage. Nevertheless, there may be existed synergistic interaction in the soil-microbes-rice system at mature stage. These findings may provide a better understanding of regulating soil respiration in agricultural land.