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ARS Home » Southeast Area » Fayetteville, Arkansas » Poultry Production and Product Safety Research » Research » Publications at this Location » Publication #417427

Research Project: Developing Best Management Practices for Poultry Litter to Improve Agronomic Value and Reduce Air, Soil and Water Pollution

Location: Poultry Production and Product Safety Research

Title: Insect frass fertilizer as soil amendment for circular systems: Impact on forage and soil health

Author
item Ashworth, Amanda
item AMORIM, HELEN - University Of Arkansas
item DRESCHER, GERSON - University Of Arkansas
item Moore Jr, Philip
item Rojas, Maria
item Morales Ramos, Juan
item Donoghue, Ann

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2025
Publication Date: 1/24/2025
Citation: Ashworth, A.J., Amorim, H.C., Drescher, G., Moore Jr, P.A., Rojas, M.G., Morales Ramos, J.A., Donoghue, A.M. 2025. Insect frass fertilizer as soil amendment for circular systems: Impact on forage and soil health. Scientific Reports. 15. Article 3024. https://doi.org/10.1038/s41598-025-87075-8.
DOI: https://doi.org/10.1038/s41598-025-87075-8

Interpretive Summary: Insect farms are expanding worldwide in response to growing demands for sustainable protein sources for animal feed. Insect rearing, also called a "mini livestock", needs less land and water and can utilize food waste as feed, which can reduce production costs and help lessen the negative impacts of landfills on the environment. The insect excreta or "frass" contains nutrients that may help boost soil health and benefit crop production, although to date, few researchers have investigated crop and soil health outcomes of this novel, value-added manure. Thus, in the present study, scientists tested forage crop yield and quality responses, as well as soil health and greenhouse gas emission responses to insect frass compared to poultry litter and commonly used ammonium nitrate. They found that soils receiving insect frass had approximately 2-3 times more carbon and soil nutrients than commonly used chemical fertilizers and poultry litter. Going forward, researchers plan to feed insects with different diets and test crop response on row crops and in organic systems in efforts to develop a more enriched, cheaper, and cleaner fertilizer and remove barriers for farmers adopting this novel fertilizer source.

Technical Abstract: Insect rearing for alternative animal protein sources or ‘mini-livestock’ is expected to dramatically increase in coming years, which will result in generating high quantities of frass (insect excreta). It is therefore necessary to find solutions allowing the efficient valorization of frass before a major upscaling of the industry takes place. Therefore, this study investigated changes in soil physiochemical properties and soil health via the soil management assessment framework (SMAF), CO2 efflux, and forage mass and nutritional value in response to Yellow mealworm (Tenebrio molitor L.) frass at two rates (3.4 and 6.8 Mg ha-1) relative to a commonly used organic manure (poultry litter at 3.4 Mg ha-1) and ammonium nitrate (67 kg N ha-1). After two years of land application, the greater frass rate increased (p<0.05) soil C, N, P, K, and Mg by 10, 12, 44, 58, and 61%, respectively, compared to ammonium nitrate. Even the lower frass rate increased soil P, K, and Mg by 37, 31, and 32%, respectively, relative to the inorganic fertilizer treatment. Relative to poultry litter, high frass rates increased soil N, K, and Mg by 12, 30, and 35%, respectively. Soil C and N at the 0-15 cm depth increased 2 and 3-fold, respectively, under the high frass rate relative to ammonium nitrate. Conversely, forage yield, SMAF, and CO2 were largely unaffected by soil amendments. Overall, frass applications substantially improved soil fertility relative to poultry litter and ammonium nitrate indicating a great potential to be used as a partial or complete substitute for mineral NPK fertilizer, which is important under the backdrop of reduced availability of chemical fertilizers globally and the importance of circular systems for sustainable intensification.