Effects of Different Cultivated Land Utilization Types on Heavy Metal Characteristics and Microbial Community...

We conducted a comprehensive analysis of soil heavy metals and the structure of the microbial community in various cultivated land types in an area with naturally high heavy metal content. 96 Topsoil and 20 soil profile samples were collected from agricultural soils: bare land (CK), corn (COR), paddy (RIC), and vegetable (VEG). The primary purpose of this investigation was to elucidate the underlying assembly mechanisms and key driving factors that influence dynamic changes in bacterial community composition across different cultivated land environments. Across all regions, substantial disparities were observed in bacterial diversity and levels of heavy metal contamination. The results of this study reveal that the average Cd and Cr levels in the four soil types were relatively high, with the greatest Cd contamination observed in the COR soil type. Notably, COR soils had the highest available As, Cd, Cr, Pb, and Zn levels compared to the other three types. Concerning bacterial diversity, the RIC soil type exhibited the highest levels, as demonstrated by high Shannon, Chao1, and ACE indices, compared to other land use types. Principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) results indicated that bacterial communities in RIC, VEG, and CK, COR soils showed a similar pattern. A deeper analysis of the microbial community revealed that Proteobacteria were the dominant phylum in agricultural soils, with Acidobacteria, Actinobacteria, and Planctomycetes closely behind. The study also revealed that pH, organic matter (OM), and heavy metals such as Cd, Pb, and Zn were the primary drivers behind the observed shifts in bacterial communities. Through the study of cultivated land use, it has been found that it changes the migration of heavy metals and the composition of soil bacterial communities, thus affecting soil health. These results have provided valuable insights into soil management to an area with naturally high heavy metal content.