Different agricultural practices specify bacterial community compositions in the soil rhizosphere and root zone

Abstract

We are only beginning to understand the influence of agricultural practices, together with soil properties and geographic factors, affect bacterial communities and their influence on the soil processes. Here, we quantify how typical agro-practices, i.e., no-tillage, ridge tillage, continuous corn cropping, and crop rotation with corn and bean, and the corresponding soil physicochemical characteristics affect bacterial diversity and community compositions of the rhizosphere and root zone soils. Results show that species richness in the rhizosphere was significantly higher than that in the root zone soils (p < 0.05), typically with more abundant Crenarchaeota and Firmicutes populations that are active members for C and N cycling. Specifically, crop rotation compared to other agro-practices was able to mediate soil pH value and the available P and thereby control the bacterial diversity pattern in the rhizosphere (p < 0.05), while tillage practices regulated the relative abundance of bacterial populations in root zone soils by varying the soil available N (p < 0.05). Analysis of biomarker patterns suggests that the observed differences in bacterial functional capabilities (e.g., nutrient cycling) are strongly related to the physicochemical properties of surrounding soils. Our results highlight the importance of soil-plant interaction in shaping soil bacterial community structure typically in the rhizosphere and root zone soils and also illustrates the challenges in linking soil ecosystem function to microbial processes.