Hermetia illucens L. Frass in Promoting Soil Fertility in Farming Systems

Following a pot trial with annual ryegrass (Lollium multiflorum Lam. (Pooideae: Poaceae)), where the effect of chemical fertilization was compared with organic fertilization with Black Soldier Fly larvae frass (BSFF), obtained by bio-digestion of cattle production effluents, and with mixed fertilization in proportions of 25%, 50%, and 75% of BSFF, the effect on crop production and soil fertility was tested in three soils of different textures, namely, sandy soil (Gleyic podzol), calcareous soil (Haplic calcisol), and clay soil (Haplic fluvisol). On top of the previous experimental device, a second year of testing was carried out with sowing of the same crop, but without any fertilizer input in all the residual soils for the different further modalities. With regard to the second sowing cycle production, the results are supportive of the expectation that fertilization with BSFF has a superior capacity for soil fertility resilience (assessed in terms of the ability to maintain or even increase soil production in the following year, in the absence of any fertilizer application) in all the soils tested in this experiment, with a significantly greater difference in the treatment corresponding to fertilization with only BSFF compared to the exclusively chemical treatment, in all the soils tested. Furthermore, BSFF, preferably as a mixed fertilizer (in a proportion until 75%), is shown to be a promising alternative for Gleyic podzol in the production of ryegrass as in the resilience and promotion of soil productivity. As far as more fertile soils are concerned (as in the case of Haplic calcisol and Haplic fluvisol), BSFF has not proved promising in terms of immediate crop production.