The Potential of Black Soldier Fly Frass to Revitalise Marginal Soils

Marginal soils have a reduced capacity for crop production due to physical and chemical limitations. These marginal soils, which are highly susceptible to degradation are dominant in sub-Saharan Africa (SSA). The high demand for agricultural land makes these soils valuable for agriculture within the smallholder sector. However, for them to be used profitably and to contribute to food security, they need to be revitalised through various rehabilitation processes. Black soldier fly frass (BSFF), a by-product of black soldier fly larvae is fast gaining recognition as a potential sustainable organic material for the resuscitation of marginal soils. BSFF is used to make an organic fertiliser known as black soldier fly frass fertiliser (BSFFF), which is rich in nutrients such as nitrogen (N), phosphorous (P), potassium (K) and a host of beneficial microbes. The fertiliser is also high in organic matter, which makes it attractive for soil structural improvement. This chapter highlights the potential of BSFFF in revitalising marginal soils, and in-turn improving crop productivity and food security in SSA. Preliminary findings from across SSA have shown improvement in soil physiochemical properties and crop growth and yield following application of frass fertiliser. However, several drawbacks have been identified such as prohibitive costs of equipment and knowledge gaps since this is still a new technology. This challenges could be addressed through collaborative research efforts, policy support and increased awareness campaign to inform farmers of the potential benefits of BSFFF. Since most of the available research came largely from laboratory and glasshouse experiments, there is need for long term field experiments on marginal soil across SSA to establish the real world effects of frass fertiliser. It also pertinent to study the potential integration of BSFFF into existing climate smart agriculture technologies such as conservation agriculture as well as the possibility of combining BSFFF with other organic amendments such vermicomposting and biochar.