Rhizoengineering influences on soil dynamics and microbial communities in post-harvest oat fields

Agricultural practices involving synthetic inputs significantly impact soil microflora and nutrient cycling, affecting soil health and fertility. The challenges are exacerbated by changing climatic conditions, with drought having the most significant impact. Microbial communities and soil functions can be enhanced through plant growth-promoting rhizobacteria (PGPR), which have emerged as a reliable and sustainable alternative. Studies recognize PGPR for its diverse roles in plant growth promotion and disease suppression, but there is a lack of studies on its effects on soil conditions. This study examined the influences of selected PGPR viz Enterobacter cloacae BHUSR1, Serratia marcescens BHUSR2, and Klebsiella aerogenes BHUSR3 on soil nutrient mobilization and microbial communities of rhizospheric soils. Seeds of Avena sativa were bioprimed with the selected PGPR before sowing. The fields were then exposed to two levels of water stress, irrigating one plot at 7 days and the other plot at 10 days intervals. Rhizospheric soil analysis of fully mature crops was done for pH, EC, moisture, nutrient content and microbial flora. It was observed that biopriming oat seeds with selected PGPR altered soil pH and electrical conductivity. Significant improvements in the soil moisture percentage and available nutrients except nitrate were recorded in the oat rhizosphere. While the bacterial counts significantly improved even in the drought-exposed fields, a decrease in fungal count was recorded in response to the PGPR. Among the selected PGPR, E . cloaceae BHUSR1 was found to be the most influential in supporting plant growth by mobilizing soil nutrients and retaining moisture in the rhizospheric region under simulated drought conditions.