Applications of Black Solider Fly (Hermetia illucens) Larvae Frass on Sweetpotato Slip Production, Mineral Content and Benefit-Cost Analysis

Black soldier fly (Hermetia illucens) larvae (BSFL) production is increasing, which will leaves substantial amounts of leftover excrement, called 'frass' that may be a beneficial organic fertilizer. In this study, sweetpotato (SP) (Ipomoea batatas) cuttings ('slips'), were grown with BSFL frass as a one-time top dressing at either 333.7g/m(2) or 667.4g/m(2), respectively, or daily applications of either BSFL frass tea (225g in 3.78 L) or an inorganic fertilizer (control). The nitrogen-phosphorus-potassium of the BSFL frass and inorganic fertilizer was 6.2-1.4-1.7 and 10-30-20, respectively. After three weeks, no significant difference in length, number of nodes and stem diameter were found in the 667 g/m(2) frass treatment versus control, while these values were significantly lowest in the frass tea treatment. Slip manganese and copper were significantly lower and higher, respectively, in the control compared to the 333 and 667 g/m(2) frass treatments. Iron, copper, manganese, zinc and magnesium were significantly lower in slips from the tea treatment and was excluded from economical analysis due to minimal growth. Benefit-cost analysis showed the highest benefit-cost ratio was for the 333 and 667 g/m(2) frass treatments at 3.65 and 3.62, respectively, compared to the control at 3.48.