Examining the utility of black soldier fly larvae composting on urban farms

View the project final report

Commodities

• Vegetables: carrots, cucurbits, tomatoes
• Animals: black soldier fly
• Miscellaneous: compost

Practices

• Animal Production: manure management
• Crop Production: organic fertilizers
• Education and Training: on-farm/ranch research
• Soil Management: composting
• Sustainable Communities: urban agriculture

Urban farmers face many unique challenges associated with the urban environment in which they produce. One of the most expensive and limited resources is access to healthy soils. There is often low organic matter and industrial contaminants present in urban soils, resulting in the need for remediation, such as capping and importing topsoil and compost. Recently, black soldier fly larvae (Hermetia illucens; BSF) have been recognized as an efficient organism used to break-down organic matter and produce a soil amendment comparable to traditional fertilizers. These fly larvae can feed on a wide range of organic waste (plant material, biosolids, food waste, etc.), can break down contaminants such as pharmaceuticals or pesticides, and impact the bioavailability of heavy metals. The resulting material is a digestate that can be applied as a soil amendment, much like the vermicomposting processes of worms. Fly pupae can be harvested and used as a nutrient dense feedstock for livestock or reared to adults to continue the cycle of composting.  Knowledge gaps remain regarding the impact of feedstock on the nutritional quality of the digestate for crop production and the application and implementation of BSF composting on-farm. My research aims to fill in these gaps, increasing our understanding of BSF composting for vegetable production and implementing on-farm capabilities to generate compost with organic waste produced on-farm or within the community. Ultimately, I hope to provide a strategy for producing nutrient-dense soil amendments tailored to urban farming systems, thus increasing the sustainability of locally grown produce on limited-resource farms.  Through laboratory assays and on-farm trials I will identify the optimal feed source (food waste, plant debris, spent brewing grains, manure) and stocking rates of BSF to produce viable compost for vegetable production. The digestate from this process (compost product) will be evaluated as a soil amendment for the production of vegetables. Results from this work will be disseminated through on-farm demonstrations with collaborating urban farmers, a field day at our research farm, extension publications and presentations/demonstrations at grower meetings.

Major learning outcomes from this study include: 1) optimization of feedstock for black soldier fly (BSF) compost production, 2) increased farmer knowledge and understanding of BSF composting and its application in urban farming, 3) acquisition of skills to produce and evaluate BSF digestate. Action outcomes include:  1) adoption of on-farm compost production using BSF, 2) reductions in organic waste streams moving off-farm or to landfills, 3) reduced reliance on external inputs to build organic matter on urban farms. We will achieve these outcomes through applied research, dissemination of research results with on-farm trials and learning events, the publication of extension materials and presentations/demonstrations at grower conferences.  Major condition outcomes resulting from this study include improved economic well-being of urban farmers for reduced outsourcing of soil amendments, efficient use of on-farm and community organic waste streams, and increased access to healthy foods in food-insecure urban communities through sustainable urban farming. This project focuses on improving the sustainability of urban agricultural systems by reducing the need to purchase soil through an efficient way to compost on-farm.