Glasshouse Evaluation of the Black Soldier Fly Waste Product HexaFrass™ as an Organic Fertilizer

Abstract

The mass farming of the black soldier fly (BSF; Hermetia illucens L.), to produce insect-based feed for livestock and fish, results in considerable amounts of insect frass, which contains substantial amounts of organic matter and bioavailable nutrients. Insect frass has shown good potential as a soil amendment and organic fertilizer. This study examined the effects of HexaFrass™ on the growth of common vegetables and herbs under glasshouse conditions. In an organically-rich potting mix, HexaFrass™ increased shoot dry weight by an average of 25%, although this effect was variable among test plants. In other trials, application of HexaFrass™ caused an increase in plant growth similar to that obtained by applying chicken manure and a commercial organic fertilizer. Increases in shoot and root dry weight showed quadratic relationships with HexaFrass™ dose, indicating that application of excessive quantities could lead to plant inhibition. Shoot:root dry matter ratio tended to increase with HexaFrass™ dose suggesting there was no specific stimulation or enhancement of root growth. Overall, these results provide further evidence of the potential of insect frass as an effective organic fertilizer for vegetables and herbs.

Transmission of tetracycline resistance genes and microbiomes from manure-borne black soldier fly larvae frass to rhizosphere soil and pakchoi endophytes

“…Nutritional and economic value of pakchoi and residual TRGs BSFL frass can provide sufficient nutrition for the growth of pakchoi similar to chicken manure (Figures 3A,C), but the nutrient content between them is not completely consistent. Similarly, BSFL frass applied to corn (Garttling et al, 2020), sweet potato (Romano et al, 2022), vegetables, and herbs (Borkent and Hodge, 2021) has the potential to be an effective organic fertilizer. Although the total nitrogen content in BSFL frass was lower than that in chicken manure (Figure 3A), this may be because nitrogen is a key factor in the transformation of BSFL crude protein during growth.…”

“…However, an increase in the amount of fertilizer may cause negative effects. Borkent and Hodge (2021) used BSFL frass as a fertilizer to grow basil, lettuce, and parsley and found that excessive application of this fertilizer resulted in restricted root development.…”

Growth of Red Amaranth (Amaranthus cruentus L.) Cultivated on Soil-Based Substrate Amended with a Residue of the Black Soldier Fly Larvae Containing Heavy Metals

“…However, the roots were healthy, as indicated by higher root biomass if 10% BSF was mixed into the soil-based substrate, compared to higher BSF application rates, i.e., the root elongation was suppressed by 30-50% at higher application rates (Table 2). In contrast, Borkent and Hodge (2021) reported that the application of BSF waste product increased the dry weight of the shoot and root of several herb and vegetable plants and had similar effects to other commonly-used organic fertilizers, such as chicken manure.…”

A biochemical analysis of Black Soldier fly (Hermetia illucens) larval frass plant growth promoting activity

“…A number of researchers have conflated plant growth promoting activity associated with leftover waste byproducts recovered from Black Soldier fly (Hermetia illucens) larva (BSFL) processed feedstocks with BSFL frass even though it is generally well-known that much of the residual leftover byproduct, aside from frass, consists of leftover feedstock in varying stages of degradation, insect exuviate, and microorganisms [1][2][3][4][5][6][7][8]. Whereas there is no question that BSFL while feeding and growing off of feedstocks leave frass deposits in the feedstocks on which they feed, frass, separated free of contaminating residual leftover feedstocks processed by larvae has not heretofore been examined for its role in conferring to soil plant growth promoting activity upon its amendment into soil.…”