Bacterial Diversity and Functional Dynamics in the Soybean ( <scp> <i>Glycine max</i> </scp> L.) Rhizosphere Under Different Organic Fertilisation

Soybean (Glycine max L.) is a globally important legume for oil and protein production, yet its responses to specific organic fertilisation practices remain insufficiently understood. Organic amendments such as cattle dung and poultry manure are sustainable alternatives to inorganic fertilisers, but their effects on the soybean rhizosphere microbiome remain poorly characterised. This study investigated microbial community structure and functional diversity under poultry manure and cattle dung treatments. Rhizospheric soils were collected from treated plots, untreated controls and bulk soil and then subjected to physicochemical analysis. DNA extracted from samples was analysed using 16S rRNA gene sequencing on the Illumina NovaSeq 6000 platform, with data processed in QIIME 2 (v2019.1). Poultry manure increased available phosphorus (28%) and calcium (19%), while cattle dung enhanced potassium (22%) and magnesium (17%). Microbial community composition shifted significantly, with poultry manure promoting copiotrophic taxa such as Burkholderia and Cupriavidus and cattle dung enriching decomposers including Paenibacillus and Treponema. Alpha diversity was highest in poultry manure (Shannon index 6.2) and bulk soil (6.0) and lowest in cattle dung (5.1). Functional predictions indicated retention of core metabolic pathways, suggesting functional redundancy. Overall, organic fertilisation reshapes microbial communities while maintaining essential functions, supporting sustainable soybean cultivation.