Black Soldier Fly Frass Shows Promise as Organic Fertilizer for Maize Production in Madagascar

New research published in the peer-reviewed journal Frontiers demonstrates that Black Soldier Fly (BSF) frass – the organic waste produced by BSF larvae – can significantly boost maize production in southeastern Madagascar. The study, conducted by researchers from the Madagascar Biodiversity Center (MBC) and Health In Harmony (HIH), reveals that composted BSF frass increased maize yields by 38% compared to traditional cattle manure, offering a sustainable pathway to address food insecurity in the region.

"These findings are particularly significant for smallholder farmers in Madagascar who face persistent challenges with soil fertility and food production," says Dr. Sakib Burza, Chief Health & Innovation Officer at Health In Harmony. "By demonstrating that composted BSF frass can enhance crop yields even at sub-recommended fertilizer doses, this research provides a locally accessible solution that supports both agricultural productivity and environmental sustainability.”

The field trial, conducted in Morafeno village near Farafangana District, tested four treatments: composted BSF frass, fresh BSF frass, cattle manure, and no fertilizer. Composted BSF frass produced the highest total grain yield at 1.98 tons per hectare and demonstrated superior agronomic nitrogen efficiency. Notably, the unfertilized control plots produced no harvestable maize, underscoring the critical need for nutrient inputs in the region's acidic soils.

"Our results show that composting BSF frass for five weeks transforms it into a highly effective organic fertilizer," says Cédrique L. Solofondranohatra, lead researcher and Director of Small Farms Programs at the Madagascar Biodiversity Center. "Even at one-third of the recommended nitrogen input, composted BSF frass achieved 57% of the yield obtained under full fertilizer recommendations. This is crucial for smallholder farmers who cannot afford full-dose commercial fertilizers."

What makes this research particularly notable is its community-led approach. Rather than conducting experiments in controlled laboratory settings, researchers worked alongside farmers in Morafeno village who tested BSF frass on their own fields using their own agricultural practices. “Working directly with community members in their own fields gave us insights we could never have gained in a research station," Solofondranohatra said. 

Madagascar faces severe food insecurity, with maize serving as a critical crop for both nutrition and income among rural households. BSF larvae efficiently convert organic waste into nutrient-rich frass, creating a circular economy approach that addresses both waste management and agricultural productivity. The composting process proved essential – fresh frass significantly reduced seed germination due to phytotoxic compounds, while five weeks of composting eliminated these effects.

Brunot, a maize farmer and village king in Morafeno village who participated in the trial, says the results have changed his approach to farming. "Before this study, when we couldn't afford fertilizer, we would get no harvest at all. Now I am learning to compost BSF frass, and I can see my maize plants growing stronger. This gives me hope that I can feed my family and have maize to sell at the market."

The field trial tested each fertilizer type in multiple plots across Brunot’s field to ensure fair comparisons and control for variations in soil quality and environmental conditions. The trial ran during the November 2024 to February 2025 growing season. Researchers measured germination rates, plant height, grain yield, and nitrogen use efficiency. All fertilizer treatments significantly outperformed the control, with composted BSF frass showing the highest agronomic efficiency at 46 kg grain per kg of nitrogen applied.

This research provides crucial evidence for organizations working to improve food security and environmental sustainability in Madagascar and similar contexts. The findings suggest that BSF farming could offer smallholder farmers access to high-quality organic fertilizer while reducing reliance on expensive commercial inputs.

The next steps involve scaling BSF production systems across the region. Health In Harmony is implementing 350 BSF farms across 20 villages in the Manombo region, with 10% already operational and successfully doubling production after the first harvest. Plans are underway to expand to the Ikongo region with another 1,000 farms in partnership with Doctors Without Borders (MSF).

This agricultural research complements HIH and MBC's ongoing work examining community acceptance of BSF larvae as a food source in the region, with findings expected to be published in PLOS ONE. Together, these studies highlight the dual potential of BSF systems to address both soil fertility and protein nutrition challenges facing Madagascar's rural communities.

The research paper, "Preliminary field evaluation of black soldier fly frass as an organic fertilizer on maize (Zea mays L.) growth and yield in southeastern Madagascar," is available in Frontiers.