Effects of heavy metals on soil microbial community of different land use types

To evaluate soil environmental quality of introduced new crops and other traditional crops, and to understand the importance of response of soil microbial community to heavy metal stress, rhizosphere soil samples of different land use types(Sphagnum farming, rice field, grassland and bare land) in Dading Village, Duyun City, Guizhou Province of China were selected as research objects. The differences of soil chemical properties, heavy metal concentration and microbial community among different land use types were compared. The abundance and structural diversity of microbial communities in soil samples were analyzed by 16S rDNA sequencing, the relationship between soil pollution characteristics and microbial community in farmland was studied. The results showed that the different land use types planting different agricultural products under the same growing environment were subject to different heavy metal pollution. Soil chemical properties and heavy metals had significant effects on the soil microbial community. Proteobacteria, Actinobacteriota and Acidobacteriota were the most dominant groups of bacteria. The soil microorganisms responded more actively to the variability of pH, SOM and AK contents, although the variability was not high. With the increase of pH value, the abundance of the dominant species Proteobacteria also increased. Verrucomicrobiota had a better tolerance to the heavy metal Hg. Verrucomicrobiota and Firmicutes had strong resistance to the heavy metal Cd. These results deepen our understanding of the changes and aggregation of microorganisms under different land use patterns in heavy-metal contaminated farmland soils.