They are the most numerous animals on Earth, and yet we are only just beginning to understand the fertilizing and biostimulating properties of their excrement. Close up of frass of insects.
Concept frass includes bioproducts generated by insect breeding, such as feces, debris, or metamorphosis shells. In Quebec, there are three forms of breeding: mealworms, black soldier flies, and grasshoppers. “The mealworm and cricket manure are quite dry, while that of the black soldier fly is wet and will require drying and conditioning,” describes Emmanuel Caron-Garant, a research professional at Biopterre. The composition and particle size of frass will vary depending on diet and microbiology. For example, if insects are fed fruit, there will be more yeast. »
More benefits …
Without reaching the level of a synthetic fertilizer, the fertilizer value is off frass is not insignificant and has an effect on plant growth, notes Louise Hénault-Éthier, associate professor at the National Institute for Scientific Research (INRS) and director of the Center Eau Terre Environnement. “According to studies, the nutrients in frass is rapidly assimilated or mineralized by the plant. In addition to macronutrients, there are also micronutrients. »
It is significant, unlike other organic changes frass can lower the pH of the soil, as observed in a controlled environment. “This can prove beneficial as too high a pH can make nutrients less bioavailable,” she adds.
Several dynamics will overlap with the use of frass. “There is a rapid release of soluble and assimilable compounds, and at the same time a slow release of carbon and nitrogen polymers, thanks to the microbiology of the earth,” adds Emmanuel Caron-Garant. This is without taking into account the biostimulatory effects of certain molecules such as chitin, which come from insect shells. In its presence, the plant activates its natural defenses and provides better resistance to stress. that frass would also offer increased resistance to drought and excess water.
… But also boundaries
However, insect breeders have to deal with certain challenges, such as being able to produce one frass uniformly from one production cycle to another, but also to prevent the presence of pathogens. Also some frass may have an allergenic effect on the airway level – just like seafood – the use of protective equipment may be necessary for those who handle these products.
“This is a start-up industry and there is a lack of knowledge, including on the detection and diagnosis of diseases in farms,” concludes Emmanuel Caron-Garant. The tests performed by Biopterre and its partners on various types of packaging and greenhouse and laboratory applications should provide some answers.
A sector in development
Currently, the biggest obstacle to its use on a larger scale is the price – from $ 17 to $ 27 per kilo – which can be largely attributed to its low availability. In Quebec, there are about twenty breeders whose total production will vary between 350 and 1,500 tonnes by 2020, according to estimates by Mrs Hénault-Éthier. “Given that a single spoonful per liter of soil can generate remarkable effects, use is currently directed at more embedded crops where we want to seek the biostimulating effects of frass, the researcher states. However, this limit is temporary as the industry is growing rapidly. »
Louise Hénault-Éthier and Emmanuel Caron-Garant were speakers at Montérégie Horticultural Fridays.