Biochar and manure addition influenced soil microbial community structure and enzymatic activities at eroded and depositional landscape positions

Biochar and manure application can modify soil microbial community structure and enhance biochemical activities. However, the studies about the influence of biochar and manure on the microbial communities on different geomorphological landforms (depositional and eroded landscapes) are scarce. In this study, we investigated the responses of soil biochemical activities and microbial communities to the addition of pinewood biochar, dairy manure (DM), and the dairy manure and pinewood biochar mixture (DMP) at a rate of 10 Mg ha(-1), respectively, in comparison with control (CNT) at eroded and depositional landscape positions over 5 years. Data showed that the DMP treatment significantly increased cold-water-soluble organic carbon and hot-water-soluble organic carbon at the depositional landscape than CNT soils. Application of DMP increased total phospholipid fatty acid (PLFA) and bacterial PLFA by 31% and 20% compared with the CNT at the depositional landscape, respectively. At eroded landscape, total PLFAs and total bacterial PLFAs biomass concentrations were found 39% and 90% higher with DM than CNT soils. The addition of DM and DMP increased the activities of enzymes that are involved in the major nutrient cycling at depositional and eroded landscapes. At the phylum level, the proportion of Bacteroidetes was found lower in DMP, but the proportion of phylum Proteobacteria and Acidobacteria were increased. In conclusion, our study revealed that DMP influenced the labile nutrient pool, altered the microbial community structure, and increased bacterial composition and enzymatic activities at both the landscape positions.