Black soldier fly (Hermetia illucens) frass on sweet-potato (Ipomea batatas) slip production with aquaponics

Authors: ROMANO, NICHOLAS - University Of Arkansas At Pine Bluff; Webster, Carl; DATTA, SURJYA - University Of Arkansas At Pine Bluff; PANDE, SASMITA - University Of Arkansas At Pine Bluff; FISCHER, HAYDEN - University Of Arkansas At Pine Bluff; SINHA, AMIT - University Of Arkansas At Pine Bluff; Huskey, George; Rawles, Steven - Steve; FRANCIS, SHAUN - University Of Arkansas At Pine Bluff

Submitted to: Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2023
Publication Date: 9/29/2023
Citation: Romano, N., Webster, C.D., Datta, S.N., Pande, S.J., Fischer, H., Sinha, A., Huskey Jr, G., Rawles, S.D., Francis, S. 2023. Black soldier fly (Hermetia illucens) frass on sweet-potato (Ipomea batatas) slip production with aquaponics. Horticulturae. 9. Article 1088. https://doi.org/10.3390/horticulturae9101088.
DOI: https://doi.org/10.3390/horticulturae9101088

Interpretive Summary: Aquaponics integrates fish and plant farming where waste produced by the fish act as nutrients for plants. Therefore, this system can maintain good water quality, reduce water usage, and obtain two (or more) marketable products for producers/farmers. Aquaponics appears particularly well suited to urban areas where space is limited to provide fresh and nutritional food to local populace. However, there are often some nutrients that become limiting and thus it is common for additional supplementations to optimize plant production. One source for various nutrients is black soldier fly larvae (BSFL) frass, which is a combination of larvae manure and chitin, and when used as a soil amendment, has enhanced plant production similar or even better than commercial fertilizers. The nutritional composition of frass is greatly influenced by the initial food provided. Obtaining sufficient amount of sweet potato slips is a bottleneck to the sweet potato industry. Sweet potato slips are commonly grown in greenhouses before being planted outside in soil for their root production; however, aquaponics may be an excellent production method for slips. An 8-week study was conducted in which BSFL frass was used as a nutrient source for aquaponically-produced sweet potato slips and culture of Nile tilapia. The BSFL frass was produced in the lab with fruits/tuber (low nitrogen frass) or spoiled fish feeds (high nitrogen frass). After the BSF larvae were harvested, the frass was oven-dried at 100C for 48 hours, and then hammer-milled into a fine powder. In six separate aquaponic systems, a total of 200 sweet potato slips were grown in gravel and after one week and were harvested each week (total of 7 harvests) for slip (offshoots) production. BSFL frass (High N and Low N) were added to the gravel media as a nutrient source daily. After 8 weeks, overall production between slips receiving high or low N frass were not significantly different, although the final production was slightly higher with low N frass. Under normal commercial sweet potato slip production methods, slips are normally harvested once every three weeks with each having 6-7 nodes. In this study, slips were harvested every week with 8-9 nodes. This substantially better production was likely due to water and nutrients being constantly available for vegetative growth. Aquaponic production of sweet potato slips seems to offer a highly productive strategy for commercial sweet potato production, while producing a highly nutritious secondary protein source (fish). Further research to expand aquaponic production system of sweet potato slips is warranted.

Technical Abstract: Aquaponics integrates fish and plant farming where waste produced by the fish act as nutrients for plants. Therefore, this system can maintain good water quality, reduce water usage, and obtain two (or more) marketable products for producers/farmers. Aquaponics appears particularly well suited to urban areas where space is limited to provide fresh and nutritional food to local populace. However, there are often some nutrients that become limiting and thus it is common for additional supplementations to optimize plant production. One source for various nutrients is black soldier fly larvae (BSFL) frass, which is a combination of larvae manure and chitin, and when used as a soil amendment, has enhanced plant production similar or even better than commercial fertilizers. The nutritional composition of frass is greatly influenced by the initial food provided. Obtaining sufficient amount of sweet potato slips is a bottleneck to the sweet potato industry. Sweet potato slips are commonly grown in greenhouses before being planted outside in soil for their root production; however, aquaponics may be an excellent production method for slips. An 8-week study was conducted in which BSFL frass was used as a nutrient source for aquaponically-produced sweet potato slips and culture of Nile tilapia. The BSFL frass was produced in the lab with fruits/tuber (low nitrogen frass) or spoiled fish feeds (high nitrogen frass). After the BSF larvae were harvested, the frass was oven-dried at 100C for 48 hours, and then hammer-milled into a fine powder. In six separate aquaponic systems, a total of 200 sweet potato slips were grown in gravel and after one week and were harvested each week (total of 7 harvests) for slip (offshoots) production. BSFL frass (High N and Low N) were added to the gravel media as a nutrient source daily. After 8 weeks, overall production between slips receiving high or low N frass were not significantly different, although the final production was slightly higher with low N frass. Under normal commercial sweet potato slip production methods, slips are normally harvested once every three weeks with each having 6-7 nodes. In this study, slips were harvested every week with 8-9 nodes. This substantially better production was likely due to water and nutrients being constantly available for vegetative growth. Aquaponic production of sweet potato slips seems to offer a highly productive strategy for commercial sweet potato production, while producing a highly nutritious secondary protein source (fish). Further research to expand aquaponic production system of sweet potato slips is warranted.