Economic and ecological values of frass fertiliser from black soldier fly agro-industrial waste processing

Abstract

The sustainable utilisation of black soldier fly (BSF) for recycling organic waste into high-quality protein feed and organic fertiliser with a low environmental footprint is gaining momentum worldwide. Although BSF farming is becoming a rapidly growing agribusiness, studies on the BSF farming’s economic aspects are limited. This study analysed the economic benefits of farming BSF for animal feeds and composted frass, called frass fertiliser (FF) production using experimental data. The BSF larvae were fed on brewery spent grain amended with sawdust, biochar, and gypsum to determine the cost-effective feed and other by-products production. The agronomic performance of FF on the maize crop was assessed using field experiments. Our results demonstrated that sourcing and preparing the waste substrate for rearing the BSF larvae accounts for 81-90% of the total BSF production cost. The utilisation of FF as an additional value-added product would increase farmer’s net income by 5-15 folds compared to BSF farming alone. Feedstock amended with 20% biochar increased net income by 10-64% for BSF larvae and FF production than other feedstocks. Production of one megagram (Mg) of dried BSF larvae (USD 900) would generate 10-34 Mg of FF worth USD 3,000-10,200. Maize grown on plots treated with FF yielded 29-44% higher net income than maize harvested from plots amended with commercial organic fertiliser. Furthermore, smallholder insect farmers’ direct use of FF for maize production would generate 30-232% higher net income than farmers purchasing similar FF. Our results demonstrate for the first time the role of insect farming in circular economy and justify the opportunities for future investments that would lead to enhanced sustainability for agricultural and food systems, especially for smallholder farmers in low- and middle-income countries.

Systematic review and meta‐analysis of production performance of aquaculture species fed dietary insect meals

“…20 For instance, the substrate for H. illucens accounted for 81%-90% of total farming costs and increasing use of by-products from sawdust in combination with brewery spent grain considerably reduced the cost of rearing, thus more income generation. 89 Rearing crickets for animal feeds is only profitable when weeds or organic side streams are employed. 90 Production of H. illucens fed by-products was more environmentally effective than plant-and animal-based substrates.…”

Laboratory‐adapted and wild‐type black soldier flies express differential plasticity in bioconversion and nutrition when reared on urban food waste streams

“…40,41 The BSF industry has often faced the difficulty of selecting an effective rearing substrate that is environmentally sustainable as well as economically viable. 17 Considering diverse food waste streams, 3 breeding different lineages of BSF as sustainable bio-converters for specialized waste streams could be an effective strategy. In addition, BSF companies that operate with wastes from various sources rather than a single, stable source may consider targeted breeding for greater plasticity as a viable strategy.…”

“…16 However, one of the major hurdles faced in BSF farming is in the selection of effective rearing substrates. 17 In many urban cities that are in the early stages of employing BSF solutions to waste management (like Singapore), current practices are limited to homogeneous and often plant-only food waste streams. 18 This is due to evolving policy regulations as well as operational challenges in dealing with heterogeneous food wastes that contain non-plant materials.…”

“…However, one of the major hurdles faced in BSF farming is in the selection of effective rearing substrates 17 . In many urban cities that are in the early stages of employing BSF solutions to waste management (like Singapore), current practices are limited to homogeneous and often plant‐only food waste streams 18 .…”

Insect rearing on biowaste represents a competitive advantage for fish farming

“…90,91 Employee costs are also currently a major cost driver for BSFL. If the IFA cannot produce 1 kg of BSFL at a price level of 3-4 €/kg [88][89][90][91][92] or purchase living BSFL at 3-5 €/kg, [91][92][93][94][95][96] its application is most likely to be worthwhile only for fish with a high market value. 97,98 Other prerequisites for reducing insect production costs include gate fees for biowaste processing.…”