Response of Soil Microbial Community (Bacteria and Fungi) to Organic and Inorganic Amendments Using Tomato as a Test Crop

A field experiment was conducted to evaluate the response of soil microorganisms (bacteria and fungi), to some soil amendments (organic and inorganic) at site A and site B. The experiments were laid out in a randomized complete block design (RCBD). The treatments applied were compost (3.4 t/ha), poultry manure (4.2 t/ha), Tithonia diversifolia (4.8 t/ha), NPK (15:15:15) (0.8 t/ha) at 120 kg N/ha, and the control. Treatments were replicated three times. Tomato seedlings were raised in the nursery and transplanted to the field after 3 weeks with a spacing of 50 × 50 cm. Soil microbiomes (Fungi and Bacteria) were isolated using the serial dilution technique. Compost improved both the total number of fungi by 12%–178% and diversity by 1.09%–85% compared to the other amendments at both sites, while the diversity of bacteria was increased more by Tithonia diversifolia (11%–75%). The total number of bacteria was highest in plots amended with compost at site A. Compost had the highest percentage of bacteria suppressed compared to other amendments studied at both sites (27.3% and 28.5%, respectively). NPK had the highest bacteria suppression at site A. The plot amended with NPK had the highest percentage of bacteria enhanced at site A. NPK had the highest at site B. Poultry had the highest reduction in bacteria at site A. Tithonia diversifolia had the highest percentage proliferation of allochthonous bacteria at both sites with 23.7% and 27.7%, respectively, while compost plots had the least allochthonous bacteria at both sites. At both sites, the percentage of suppressed fungi was highest in plots amended with poultry manure and control. Compost and T. diversifolia had the highest percentage of fungus growth reduction in site A (26.3%). At site A, compost had the highest percentage of allochthonous fungi (29%). Application of compost, poultry manure, and Tithonia diversifolia is recommended for the improvement of soil microbial properties.