Abstract

This study investigated the impact of soil amendment with compost on arbuscular mycorrhizal fungi (AMF) population/spore numbers and diversity, and also on soil bacterial population and diversity. Six (6) levels of compost (0g –Control soil, 200g, 400g, 600g, 800g, and 1000g), in  a Randomized Complete Block Design (RBCD) was adopted to determine soil biota diversity. AMF spore were extracted from the soil and identified, and AMF colonization of the roots of Okra (Abelmoschus esculentus) was also determined. Cultured bacteria from soil samples were enumerated, isolated, characterized. Analysis of variance (ANOVA) at P< 0.05 was performed on the data obtained and Duncan multiple range test was used to separate the mean values. Results of the study shows that microbial counts were higher in soil, with total bacterial and fungal counts of 9.2 x 10⁶ CFU/g and 2.67 x 10⁴ CFU/g respectively, compared to that of compost 3.63 x 10⁶ CFU/g and 2.30 x 10⁴ CFU/g respectively; the highest spore count was observed at the 1000g compost level (225 spores), followed by the 800g level (166.67 spores), while the lowest count was in 0g compost rate –Control soil (72.67 spores). On the other hand, the total bacteria population ranged from 5.10 x 106 CFU/g to 12.51 x 106 CFU/g, with significant differences indicating higher microbial presence in soils with increased compost application. A total of four AMF morphological types were identified belonging to four different genera, these include Acaulospora, Rhizophagus, Gigaspora, Funneliformis. The study concluded that adding compost to soil brings many benefits for soil health and diversity of soil microorganisms.