Investigation of the influence of biofertilizer synthesized using microbial inoculums on the growth performance of two agricultural crops

Abstract

In this work, biofertilizer was synthesized by mixing sawdust and other nitrogenous agricultural wastes into composites in the following ways: S1 (sawdust + chicken litter + vegetable waste), S2 (sawdust + sewage sludge + vegetable waste) and S3 (sawdust only as the control) respectively using actinomycetes as the microbial inoculums. In-vessel method of composting was employed with 120 L capacity polyethylene (PET) container as the bioreactor for the pilot scale study. Microorganisms were isolated from landfill extracts. Aeration was accomplished through turning of the compost twice weekly. Nitrogen, Carbon, Organic Matter and pH were determined at 5days intervals till the end of composting exercise. Flame Atomic Absorption Spectrometer (FAAS), was used for determination of the mineral composition of the raw materials and end products. American Society for Testing and Materials was used in the Analysis of Nitrogen, Carbon, and Organic Matter contents. Biofertilizer was analyzed more for activeness as organic fertilizer in the field studies using two crops (Maize and Okra). Biochemical test revealed that six genera of Actinomycetes were isolated. Inorganic salt starch agar medium was noticed to be effective isolation media for Actinomycetes. Actinomycetes were found to be good agents for biofertilizer synthesis due to their ability to mineralize nitrogen during composting. Preliminary investigation revealed that Rothia spp gave the highest percentage degradation of cellulose (21.6 %) as well as highest percentage mineralization of nitrogen (6.87 %) after 21days of incubation. Dosage ratio of 2:1:1 w: w, moisture content of 50–60 % and 25 days was found to be the optimum condition for nitrogen mineralization. Organic matter content of composts S1 and S2 decreased significantly with time while total kjeldahl nitrogen (TkN) content of the composts increased except compost S3 which on the contrary, reduced. The maximum temperature achieved at the end of 25 days compositing of substrate S2 was 64.6 ℃. Analysis of the leaf area index (LAI) revealed 10th week after transplant to be the period of optimum growth for both crops. In addition to, all the analysis conducted pointed to the fact that influence of biofertilizer on Okra and Maize growth performance is equivalent to the growth performance of chemical fertilizer on the same crops, affirming that organic fertilizer can comfortably replace chemical fertilizer in future.