Characterization of soil microbiome diversity in rhizosphere of leguminous crops

Abstract:

Soil microbiologists and agronomists have long worked side by side yet rarely spoken the same language when describing what happens in the thin zone of soil surrounding legume roots. This research bridged that gap by characterising rhizosphere microbiome diversity under three leguminous crops—chickpea, soybean, and groundnut—and a fallow control using 16S rRNA amplicon sequencing at Tropical Lowland Agricultural College, Ibadan, Nigeria, during the 2022 growing season. Shannon diversity was highest in the chickpea rhizosphere (H' = 3.34) and lowest in the fallow control (H' = 2.18). Operational taxonomic unit (OTU) richness followed the same pattern (203 vs. 107 OTUs). Rhizobiales, Burkholderiales, and Bacillales were the three most abundant orders across all legume treatments. Nitrogen-fixing gene (nifH) copy number was 3.7× higher under chickpea than fallow. These results confirm that legume species identity shapes rhizosphere microbiome structure, with chickpea supporting the richest and most functionally active community in this tropical lowland soil.