Long-term conservation tillage influences the soil microbial community and its contribution to soil CO2 emissions in a Mollisol in Northeast China

Abstract

Conservation tillage can significantly affect the biological, chemical, and physical properties of soil. This study aimed to determine the effect of conservation tillage on the soil microbial community and respiration and on soil CO2 emissions. In this study, the effects of 10 years of conservation tillage (no-till: NT and ridge tillage: RT) on soil CO2 fluxes and soil microbial communities were assessed in a black soil in Northeast China. The annual soil CO2 emissions were higher under moldboard plow (MP) than under NT by 7.8 % (P < 0.05). The average soil microbial respiration rate from RT was higher than that from MP by 11 % (P < 0.05). Soil microbial respiration under NT (65 %) and RT (64 %) contributed more to soil CO2 emissions than MP (54 %). Total soil bacterial and fungal phospholipid fatty acids (PLFAs) were 1.6 times and 2.6 times greater under NT and RT, respectively, than under MP in the 0–5 cm layer, whereas they decreased by 21–47 % under NT and 26–41 % under RT in the 5–10, 10–20, and 20–30 cm layers. The F:B (the ratio of soil fungal PLFAs to bacterial PLFAs) varied with soil depth (0–10 cm) between conservation tillage (NT and RT) and MP. Conservation tillage induced the stratification of the soil microbial community on the vertical profile. RT increased soil microbial respiration, soil organic carbon (SOC) concentration, and soil microbial PLFAs at the 0–5 cm depth, whereas it did not influence the annual soil CO2 emissions compared to MP with a similar carbon input. These results suggested that RT might be an appropriate tillage practice for providing a better habitat for soil microbes and SOC sequestration in Northeast China.