Enhancing plant growth parameters with synergistic application of biofertilizing bacteria from forest soil and Eichhornia crassipes compost

Abstract Background The purpose of this study is to enhance the growth parameters of three plants ( Zea mays , Abelmoschus esculentus and Cucurbita pepo ) with synergistic application of biofertilizers produced with bacteria, forest soils and Eichhornia crassipes compost. Materials and methods Soil was collected from selected forests in (Etche, Ogbogoro and Choba) from various soil horizons (0–15, 15–30 and 30–45 cm) depth. Soils parameters (bacteria count and physicochemical properties) were analysed, afterwards soils from different depth were pooled together for further analysis. Soil samples from the three forests were equally mixed to form a single soil in the ratio of 1:1:1 and used to make five treatments as follow: only mixed soil (control), 2 kg of soil + 0.1 kg microbial inoculant (MI), 2 kg of soil + 0.1 kg Water Hyacinth Compost (WHC), 2 kg of soil + 0.1 kg MI + 0.1 kg WHC, and 2 kg of soil + 0.1 kg chemical fertilizer Nitrogen Phosphorus and Potassium (NPK: 20-10-10). The efficacy of the bacterial inoculant and WHC product, were tested on 3 different plants ( Abelmoschus esculentus , Zea mays and Cucurbita pepo ) in different experimental set up. Results Results of the microbial count ranged from 0.26 ± 4.50 × 10 10 to 1.00 ± 2.07 × 10 11 cfu/g for the Total Heterotrophic Bacteria (THB), Phosphate Solubilizing Bacteria (PSB) and Nitrogen Fixing Bacteria (NFB). Pseudomonas sp and Bacillus sp were the abundant PSM and NFB isolated from the soil. There was a significant improvement in the growth of the plant species as indicated in their shoots, leaves area, total chlorophyll content, germination rate, height, yield and nutrient absorption rate after 60 days of planting with the best performance recorded in the treatment with combination of MI + WHC. Also, the content of indole-3-acetic acid (IAA) and gibberellin A 4 (GA 4 ) in shoots and leaves of crops was higher in soil treated with combination of MI + WHC than other treatments. Conclusion These studies have shown that biofertilizer should be adopted in crop production to boost plant growth parameters, nutrient levels and hormones and that treatment with MI, WHC or combination of MI + WHC offered better efficiency than the use of NPK fertilizer.