Abstract
Solid residues produced by processing food waste via Microaerobic Fermentation (MF) and by Black Soldier Fly larvae (BSFL) have been proposed as soil fertilizers. Yet, little is known about their effects on plant growth. This study compares the growth of corn plants ( Zea mays ) in soil amended with MF or BSFL residue, with effects of aerated compost on corn growth over ten weeks. Corn plants grown in soil amended with MF residues were 109% taller and had 14% more leaves than those grown in traditional aerated compost (Cedar Grove). But plants grown in BSFL residues were stunted, growing 39% shorter and having 19% fewer leaves on average. Only height data was statistically significant. Results indicate that MF produced from food scraps is a suitable soil amendment product, but BSFL solid residue from a similar source is phytotoxic when amended, untreated, into soil in a ratio of one part residue to two parts soil. More research on additional post-processing methods for BSFL solid residue is needed.
Highlights
The process of composting produces a soil amendment that is rich in fiber, nitrogen (N) and phosphorous (P)
The source material was mixed in a bin and distributed between three composting units: a Garden Plus 115 gallon aerobic compost bin, a cylindrical 19 L Microaerobic Fermentation (MF) fermenter made from a drinking thermos (Rubbermaid), and a Black Soldier Fly larvae (BSFL) unit made from a plastic 68 L container with air-holes drilled into the sides, lid and bottom (Rubbermaid, Roughneck)
It was hypothesized that stunted growth may have been the result of toxic ammonium levels in the BSFL residue, this is not supported by ammonium content measurements which were lower in BSFL residues than in other residues
Summary
The process of composting produces a soil amendment that is rich in fiber, nitrogen (N) and phosphorous (P). Vermicomposting allows for processing of materials by earthworms and bacterial communities under non-thermophilic conditions (Theunissen et al, 2010). Black Soldier Fly larvae (BSFL) are used for processing of organic waste, especially manure (Liu et al, 2008; Myers et al, 2008). The larvae live in and feed off of organic matter, decreasing its volume and pathogen load (E. coli and Salmonella) (Erickson et al, 2004; Liu et al, 2008), but little is known about the effects of BSFL solid residues from food scrap processing on plant growth
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