Decomposition and nutrient release pattern of agro-processing by-products biodegraded by fly larvae in Acrisols

Fly larvae are increasingly being promoted as animal feed and their production on agro-processing by-products generates a high amount of residues. Understanding the decomposition and nutrients release pattern in the soil of these residues is of importance to evaluate their quality as soil amendment. A litter bag experiment was carried out over 75 days in southern Benin with corn bran, a mixture of soybean bran and corn bran and a mixture of soybean bran and corn hull, all biodegraded in advance by larvae of Musca domestica and Hermetia illucens. Bags with 200 g dry matter of each residue were buried in the soil. The first order equation of mono-component model Y-t = Y(0)xe(-kt) was suitable and described well the decomposition and mineralization pattern of the residues. The residues decomposed quickly and released nutrients readily into the soil. The mass remaining at the end of the decomposition process ranged between 38% and 42% of the initial weight. The half-life of the organic carbon in the residues ranged between 50 and 58 days. Organic nitrogen mineralized fast, with rates ranging between 0.007 and 0.011 day(-1). These organic residues can be used as soil amendments to improve crop productivity in an Acrisol.