Bioconversion of rice straw using lignocellulolytic microorganisms for improved soil fertility and sustainable crop productivity in Mwea, Kenya

Soil fertility in most crop producing areas in Kenya has greatly declined due to practices such as continuous cultivation and nutrient extraction through crop harvest without adequate nutrient replenishment. Presently, the need to boost sustainable food production is on the increase globally due to burgeoning population coupled with finite non-renewable resources. With a high food demand and limited land availability, farmers regularly use harmful synthetic farm inputs to increase crop productivity. Use of bioorganic farm inputs is therefore needed due to the problems associated with synthetic inputs. Bioconversion of recalcitrant and abundant rice straw in Mwea, Kenya was thus done in this study. The objective of this study was to identify and develop a consortium of microorganisms that can accelerate biodegradation of organic materials into fertilizer and improve on soil beneficial microorganisms for enhanced crop growth and yields. Lignocellulolytic microorganisms were obtained through isolation from partly decomposed rice straw. Among the microorganisms isolated, those with the best ability to degrade rice straw (rice straw is known to resist biodegradation), were selected, identified and formulated into a starter culture for composting. Lignocellulolytic abilities of the microorganisms were established using different tests that reflect the enzymatic capacities of a microorganism. Rice straw was composted using a consortium of the selected microbes alongside commercial effective microorganisms (EM) and a control where no microbes were added. Results from the composting experiment showed a significant difference in both electrical conductivity and pH readings among the treatments (P = 0.001). Nitrogen content in the resultant bioorganic fertilizer prepared using the formulated microbial starter culture was significantly higher than in the other treatment and in the control (P = 0.001). Plant growth index of the bioorganic fertilizer from the treatment with selected microbial consortium was also significantly higher than in the other treatments at P< 0.05. The results indicate that addition of the selected lignocellulolytic microorganisms significantly improved the composting process and the quality of the resultant compost. It is thus recommended that lignocelluloytic microorganisms be used to compost crop residue and other organic wastes for improved soil fertility and increased crop productivity.