Objective   Effect of applying Chamaecrista rotundifolia plant materials to decompose as green manure on the microbial communities in red orchard soil was studied.

  Method   In a simulated experiment, red soil collected from an orchard was used as blank control (CK) or as treatments with added P. americanum×P. purpureum (P) or C. rotundifolia (J). After 10-180d of incubation at 25 ℃ and constant humidity, the soils were sampled 9 times for Illumina high-throughput sequencing.

  Results   Significant alterations were observed in the microbial populations at phylum, class, order, family, and genus levels from 10d to 60d. The relative abundance decreased in 80-140d and became similar for all samples by 180d with Proteobacteria, Acidobacteria, and Actinomycetes being the dominant microbes. Proteobacteria populations in P and J became lower than in CK, while Acidobacteria rose at first and then declined as the incubation prolonged. Actinobacteria in J increased during incubation, whereas Proteobacteria, Actinomyces, Chloroflexi, Firmicutes, Bacteroides, and Verrucobacterium in P and J followed a pattern of either 3 or 2 regression function. Both P and J raised the ACE, Chao1, and Shannon indices, but lowered the Simpson index.

  Conclusion   Composting round-leaf, short-lived perennial cassia C. rotundifolia changed the composition and structure and increased the abundance and diversity of the bacterial community in the red orchard soil. However, no significantly different effects induced by the applications of C. rotundifolia and P. americanum×P. purpureum were found.