Insect rearing, as a sector that provides high-quality protein, allows upcycling of food waste into ingredients for food and feed, therefore making it suitable to turn into a zero-waste industry. Dr. Conor Watson’s research focuses on the fertilizing potential of the by-product of this industry, frass, which is a nutritious mixture of larval excrement, shed exoskeletons and undigested substrate. This approach would not only allow for the reduction of waste, but also provide high-quality protein with a lower environmental impact compared to conventional livestock farming, increase the concentration of protein in the soil and can be absorbed by plants, which in turn provide the human body with a higher protein content when ingesting food. However, in order to reduce livestock farming, Frass must also be economical for agriculture and other producers and must not have any negative environmental impacts.

Watson’s research therefore additionally investigates the potential environmental impacts of applying frass as fertilizer to soil. The performed research has so far demonstrated frass to stimulate plant growth as an organic fertilizer, which potentially eases the demand for mineral fertilisers and could promote regional nutrient circularity. It has also been acknowledged that reactive nitrogen may be lost from frass-amended soils, however, there are recommendations available on how this could be reduced. Frass has additionally been demonstrated to be a suitable soil amendment to reduce toxicity and bioavailability of heavy metals in contaminated soils.

If you are interested in delving deeper into the subject of insect frass, feel welcome to check out Dr. Watson’s published articles on the topic:

Watson, C., Schlösser, C., Vögerl, J., & Wichern, F. (2021). Excellent excrement? Frass impacts on a soil’s microbial community, processes and metal bioavailability. Applied Soil Ecology, 168, 104110.

Watson, C., Preißing, T., & Wichern, F. (2021). Plant nitrogen uptake from insect frass is affected by the nitrification rate as revealed by urease and nitrification inhibitors. Frontiers in Sustainable Food Systems, 5, 721840.

Watson, C., Houben, D., & Wichern, F. (2022). Editorial: Frass: The Legacy of Larvae–Benefits and Risks of Residues From Insect Production. Front. Sustain. Food Syst. 6: 889004. doi: 10.3389/fsufs.

Additionally to the scientific publications, you may enjoy the linked video in which Dr. Watson presents his scientific poster at the World Congress of Soil Science in Glasgow:

Excellent excrement? The potential benefits and drawbacks of soil amendment with frass – YouTube