Soil bacterial community composition and diversity respond to soil environment in rooftop agricultural system

Abstract

The rooftop farm is of increasing interest in urban food production and greening, which operates with less environmental impact than conventional farms. However, the evidence about the bacterial community composition and soil environment in rooftop farm is still insufficient. In this study, three sampling sites (the original soil sample, the soil samples after a seven-year natural cycle, and the soil samples after a seven-year microcirculation system) were selected to study soil properties, bacterial communities, and the relationship between the two in a rooftop farm. Based on high-throughput sequencing, 61 phyla, and 1125 genus were identified in 15 soil samples. Among them, Acidobacteriota and Proteobacteria were the most dominant phyla. At the genus level, microcirculation system increased the relative abundance of Nitrospira. In addition, the co-occurrence network demonstrated that the dominant soil properties to influence bacterial community were total nitrogen and organic matter in rooftop farm. Notably, microcirculation system effectively increased the contents of total nitrogen and total organic carbon by about 2 and 3.5 times, respectively, indicating the effectiveness of microcirculation system in altering rooftop soil and microbial communities. The function predictions of microbial taxa showed that the bacterial function of digestive system and excretory system significantly enriched in microcirculation system. Taken together, the microcirculation system of rooftop farm effectively improved the soil environment and altered bacterial community, which is of considerable application value in building rooftop farms.