Soil nutrient alterations and bacterial community shifts in media amended with black soldier fly larval frass: A metagenomic approach

Ameliorants improve soil's physical, chemical, and biological properties, boosting fertility and productivity.While many studies focus on their chemical effects, few have explored their impact on soil microbial changes.This study investigated changes in soil nutrients and bacterial communities in Red Yellow Podzolic soil amended with black soldier fly (BSF) frass, using metagenomic analysis.The soil, treated with BSF frass, lime, and arbuscular mycorrhizal fungi (AMF), was incubated for a period of three months.Samples included untreated soil (S), BSF frass (BF), and treated soil (TS).Nutrients were analysed using AAS and spectrophotometry, while bacterial communities were assessed via Illumina NGS.The nutrient profile of BSF frass (BF) differed significantly from that of the soil.Ameliorant application increased exchangeable K + , Mg 2+ , and Base Saturation.Metagenomic analysis revealed distinct bacterial compositions, with 753 ASVs in soil (S), 408 in BF, and 613 in treated soil (TS).The dominant genera in the soil included JG30-KF-AS9 (26%), Acidothermus (15%), and Xanthobacteraceae (5%).In treated soil (TS), the predominant genera were similar but differed in relative abundance, comprising JG30-KF-AS9 (29%), Alicyclobacillus (14%), Acidothermus (11%), and 1921-2 (6%).The abundance of Alicyclobacillus increased significantly, from 1% in the soil (S) to 14% in the treated soil (TS).The bacteriome community in BF was markedly differed, with predominant genera including Galbibacter (13%), Brevibacterium (8%), Celvibrioraceae (6%), and Moheibacter (5%).These bacteria are capable of decomposing organic matter; therefore, the use of BSF frass on acidic soil is expected to enhance soil fertility and health.