Soil microorganisms play important roles in numerous biological processes, such as nutrient cycling, greenhouse gas emissions, disease suppression, and soil structure maintenance in agro-ecosystems. Although it has been documented that soil microbial communities can be strongly influenced by agricultural practices, their evolution and adaption in response to management practices, like land use changes, are still limited. This knowledge gap restricts scientists’ ability to manage the agro-ecosystem and develop long-term sustainable production systems.

Researchers in Institute of Subtropical Agriculture (ISA) selected four agricultural land use patterns, including old rice paddy fields (ORP), magnolia nursery planting (MNP), short-term vegetable (STV) and long-term vegetable (LTV) cultivation. Among the four systems, the MNP, STV and LTV systems had been converted from ORP. They used 454 pyro sequencing method and found that when land use was changed from rice paddy to upland systems, the relative abundance of Chloroflexi increased significantly while Acidobacteria decreased remarkably. MNP displayed the highest relative abundance of genera GP1, GP2 and GP3, which were related to soil acidity. Dr. Sheng said: “it was the first time to use the 454 prosequencing method in our research group and we got 114447 qualified 16S rRNA sequences from the 20 soil samples, which described the system more clearly than the result of the cloning library method.”

They also found that it was community composition of ammonia oxidizing bacteria (AOB) but not ammonia oxidizing archaea (AOA) was strongly impacted by the agricultural land use patterns. For example, LTV induced the growth of a single super predominant AOB group. Furthermore, land use changes also significantly altered the abundance of 16S rRNA and AOB amoA genes. The results of CCA analysis indicated that soil properties, such as TP, AP, NO3-, SOC contents and pH, were the main determinants in shaping the composition of both bacteria and AOB communities.

This work was financially supported by the Natural Science Foundation of China (41071181, 41090282) and the Chinese Academy of Sciences (KZCX2-YW-T07).

The main findings of this study have published on Journal of Soils and Sediments, detail can be reached at http://link.springer.com/article/10.1007%2Fs00374-012-0767-1