Coupling intensified push–pull technology with insect frass biofertilization improves land productivity, protein yield and carbon stocks

Abstract

We evaluated agricultural innovations such as push-pull (PP), vegetable-integrated push-pull (VIPP), and black soldier fly frass fertilizer (BSFFF) for their transformative potential in rural smallholder agriculture. Using 12 cropping systems comprising two crops (maize and cowpea), BSFFF and diversified systems (PP and VIPP), we conducted a 2-year multilocation trial to evaluate impacts on crop productivity, economic benefits, and carbon stocks. Diversified cropping increased above-ground biomass, carbon stocks, and total crop yield by 4.7–11.2-fold with significant increments upon addition of BSFFF. Diverse cropping and BSFFF increased maize grain yield by more than 2-fold. Cowpea yield responded positively to BSFFF. High total yield in diverse cropping was contributed by Desmodium (12.2–12.5 t/ha) and Brachiaria (2.3–2.4 t/ha). Diverse cropping recorded high land equivalent ratios (2.0–3.3) and wheat equivalent yields (3.2–3.7) with a significant contribution of BSFFF. The highest protein yield was in diverse cropping systems, with significant contributions from cowpea and Desmodium. Diverse cropping resulted in high annual economic benefits ($6864–$7681), with more returns when BSFFF was included ($7528–$8340). Comprehensive multidimensional analysis showed VIPP coupled with BSFFF to be superior for all assessed parameters. Crop diversification accompanied by frass-based organic fertilizer improves system productivity, financial gains, carbon storage, and potentially resilience and environmental sustainability.