Insight into soil microbiome in turfs: overlooked importance of grass growth habit and defoliation. Bacteria and fungi

In this work, we examined soil microbial species richness, diversity, and composition as well as putative gene abundances for N cycling in turfs of six different species/cultivars through 16S rRNA gene and ITS high throughput sequencing. There were three cool-season grasses, creeping bentgrass, Kentucky bluegrass, and tall fescue, and three warm-season grasses, bermudagrass, St. Augustinegrass, and zoysiagrass. Of the six species, creeping bentgrass and bermudagrass were managed as a putting green with more frequent and lower-height mowing. Our data revealed that the bunch-type tall fescue yielded significantly greater microbial richness than creeping-type grasses, which propagate via rhizomes and/or stolons. Further, the more intensively mown creeping bentgrass yielded the lowest microbial richness. Similar microbial community composition was found between creeping bentgrass and bermudagrass. However, only minor differences in microbial communities were detected between warm- and cool-season grasses. Functional gene abundances for N cycling also showed high similarity between creeping bentgrass and bermudagrass, but contrasted most between creeping bentgrass and the other grass species, with the former being greater in mineralization, assimilatory nitrate reduction, and N fixation and lower in nitrification. Soil pH was found to be the most significant soil property for explaining variations of microbial community composition and structure among the six grass species, but it only explained ~ 18% and 12%, respectively, for the bacterial and fungal communities. Our results indicated the importance of grass growth habit and defoliation to regulate soil microbial community diversity, composition and potential N functions.