Potential of using indigenous microorganisms for decomposing coffee and rice crop waste into bio-fertilizer

Abstract

Agricultural waste contributes approximately 140 billion tonnes to global waste annually, much of it rich in nutrients originally absorbed from the soil. Managing this waste sustainably while replenishing soil fertility is critical for long-term agricultural productivity. In Uganda, coffee and rice husks are abundant crop residues but decompose slowly due to their high lignin and cellulose content. This study aimed to evaluate the effectiveness of Indigenous Microorganisms (IMOs) in accelerating the decomposition of coffee and rice husks and improving compost quality. The experiment was conducted at Kyambogo University Farm, Central Uganda, using a Completely Randomized Design (CRD) with four treatment combinations replicated five times. The treatments were; i i) Coffee husks + goat manure (CH+GM), ii ii) Coffee husks + goat manure + IMOs (CH+GM+IMO), iii iii) Rice husks + goat manure (RH+GM), and iv iv) Rice husks + goat manure + IMOs (RH+GM+IMO).

Each composting pit contained 25 kg of material mixed at a ratio of 1:0.5 (husks to goat manure) on a dry-weight basis. A culture of beneficial anaerobic and aerobic microorganisms was prepared from leaf litter collected from a forested area adjacent to Kyambogo University Farm so as to ensure the microbes originated from a natural (indigenous) soil ecosystem conducive for microbial diversity and proliferation. Treatments with IMOs received 1 liter of IMO solution, while controls received plain water. Data on temperature, pH, moisture content, organic matter, macronutrients (N, P, K, Ca, Mg), micronutrients, and C/N ratio were collected over a 12-week composting period.