Hermetia illucens L., known as Black Soldier Fly (BSF) appear as an opportunity to reuse vegetable by-products, as it is easy to reproduce and can be reared in agricultural side streams, allowing the production of both, animal feed (the larvae, after recycling of the vegetal debris) and soil organic fertilizer (insect frass). Although several organic fertilizers, from long ago, have been used in agriculture, there is yet a paucity of experimental data on the evaluation of the fertilization potential of BSF larvae frass (BSFF). The present study is a contribution to access the agronomic and environmental potential of the BSFF as an organic fertilizer. Within this aim, it was conducted a greenhouse experiment with ryegrass, using seven treatments of BSFF. Under the experimental conditions, the results showed a significant effect of BSFF on the overall ryegrass production, with a steady increase (significant at p 0.05, as accessed through the Tukey test) up to the treatment with a greater rate of application. In what concerns sustainability of soil productivity, at the end of the experiment, there was also positive indications, namely, a significant increase of OM, P and K, for treatments with higher N endowments, together with a constant increase of dehydrogenase activity, from the control to the higher treatment, which was significant for treatments receiving the higher dose of BSFF.

The aim of this study was to evaluate the potential agronomic value of black soldier fly larvae frass (BSFF) as an organic fertiliser in short-cycle crops, using lettuce as the test plant. Treatments consisted in applying different fertilisers (BSFF and mineral) at different doses and combinations. The experiment was carried out for 42 days and plants were analysed in terms of biomass production, while the soil was chemically characterised before and after fertilisation, in order to assess the residual nutrient concentrations. In addition, soil microbial activity was assessed through the activity of the enzymes dehydrogenase and β-glucosidase. The highest yields were obtained with an exclusive mineral fertilisation (162.5±61.8 g fresh weight) and with a mixture of organic/mineral fertilisation (144.5±16.8 g) in comparison to exclusive fertilisation with BSFF, probably due to the immobilisation and slow mineralisation rate of the N provided by frass, along with the choice of the short-cycle plant, which requires readily available nutrients. Nevertheless, the BSFF increased the soil’s organic matter and residual nutrient content after 42 days of experiment, as well as the enzymatic activity of dehydrogenase and β-glucosidase, by at least 121 and 24% in the soils fertilised with BSFF, respectively. Thus, despite not being effective as an exclusive fertiliser for a short cycle culture, the BSFF included in a mixture with mineral fertilisation, may compete with exclusive mineral fertilisation with the benefit of improving the sustainability of soil fertility and crop production.

No abstract

The relative agronomic performance of two organic fertilizers - effluents from intensive cattle farming, after composting either by traditional aerobic methods (compost) or by bio-digestion by larvae of the black soldier fly (Hermetia illucens, BSF) (frass) - in the growth of annual ryegrass (Lolium multiflorum L.) on a sandy soil was evaluated. For this purpose, a pot trial was conducted in a semi-controlled greenhouse. Eight treatments were defined, with four treatments using the compost and four treatments using frass (with a 10% nitroamoniacal nitrogen supplementation in all treatments), in addition to a negative control without fertilization, and a positive control with exclusively chemical nitroamoniacal fertilization. Regarding the biomass production, the BSF frass displayed a higher potential than the compost, with a significantly higher production from an N endowment equivalent to 280 kg ha-1 (252 kg organic N + 28 kg mineral N). While the yields obtained with compost were stable when 350 kg ha-1 (315 kg organic N + 35 kg mineral N) were provided, the yields obtained with BSF frass revealed a tendency to continue to progress with higher doses. This could be justified by the fact that the P2O5 and K2O content of BSF frass is significantly higher than that of the compost, and these nutrients continued to be mineralized over time. Furthermore, the obtained results confirm the potentiating effect of mineral fertilizers in the maximization of biomass production, when associated with organic fertilizers in adequate proportions. In addition, it was verified that the addition of frass enhanced the water use by plants, which was significantly higher than the treatments with compost, regardless of the N endowment. It was concluded that mixing chemical and organic fertilizers positively impacts soil fertility and the sustainability of the production as a whole, by increasing productivities in a sustainable way.

Here It has prospered, and in the Mediterranean Europe it has already been showing (in scientifically proven experimentation) a huge potential in the biological digestion of all kinds of organic leftovers.

Following the evolution of composting technology, the process of digestion of a biological substrate by insects (entomocomposting) represents the last stage; however, from its initial context of producing an organic fertilizer, the role of entomocomposting has been imposing itself (due to increasing demographic pressure) mainly in the safe disposal of organic waste (in rampant growth) and in the breeding of insects for food and feed, for the sake of food security. Both these last goals converge in the first, as the safest disposal of the compost is its use as organic fertilizer; but the organic substrates are of a diversified nature, as are the species of insects which have already proved themselves in entomocomposting; hence, for each of the purposes in view, the choice is vast and, in the same way, the entomocompost composition is wide-ranging. Furthermore, various types of organic substrates, in addition to a microbial flora with symbiotic effects, may sometimes be able to transmit to the frass a harmful load of heavy metals and/or, depending on the composting insect agents, the presence of microorganisms harmful to crops and to humans and animals; in these situations, the former should be encouraged, and the latter counteracted through appropriate composting technology. Directives and legislation in this area, if properly considered, constitute a fundamental basis for ensuring the appropriate use of this particular kind of organic fertilizer. Apart from the production of insects for food and feed, where the choice of which insect is determined at the outset, the preference for the insect to be used in entomocomposting should be considered according to its proficiency in biological digestion of the organic substrates available for this purpose and the fertilizing quality of the frass produced. Although a multitude of species have been evaluated, to date, for the digestion of organic substrates, most have been used in assessing their specific potential for certain functionalities of frass related to crop nutrition and health, but there are few which, either by prolificacy, proficiency or rapidity in digesting substrates, exhibit capacity to compete in rural environment; nevertheless, new species could be evaluated in the framework of the research of competitors for entomocomposting of all or each substrate type and for each of the main anticipated objectives, meanwhile, genetic improvement to obtain new strains specialized for different organic substrates has already started to take its first steps. In addition to the binomial “insect x substrate” the composting technology constitutes the third fundamental factor for the efficiency of the process. Insects use as a composting agent has been suggested several decades ago, but it was only in the last decade that this process grown from the garden to the factory. Within rural areas, entomocomposting could play a key role within a circular economy, where recycling and reusing potentially polluting wastes safely returns to the land the enduring fertility that enables the sustained production that generated them, requiring no particularly upscale installations, equipment or technical training; it can, therefore, be adapted to any size of agricultural holding, from smallholdings to large industrial holdings, on the other hand, and in order to obtain a controlled production and high quality entomocompost, it is needed to implement industrial technologies and the composting unit can achieve a very high production per square meter, comparing with traditional composting methods. However, whether from the perspective of agriculture, livestock or forestry, the production of waste for entomocomposting always falls far short of the necessary scale, and therefore always requiring the use of biodigested organic waste from agricultural industries, provided that the necessary precautions are taken; in any case, it always constitutes added value, due to the products it generates, in addition to the inestimable value of the productive disposal of potentially polluting products. Despite all the advantages mentioned above, the controversy over the organic vs. mineral fertilizer option persists, often fuelled by myths on both sides, but the successes already achieved with insect entomocomposts, such as the black soldier fly (Hermetia illucens L.) or the mealworm (Tenebrio molitor L.), in field trials, which are gradually adding up, anticipate an important role for insects in safeguarding global food and environmental security.

Black Soldier Fly (BSF)-Curriculum vitaeIn reality, the black soldier fly (Hermetia illucens L.), from the taxonomic family Stratiomidae, is not a fly, like the one that sometimes bothers us (the Musca domestica L.) and does not even belong to the same "taxonomic" family of the Muscidae. Perhaps that is why they do not tolerate each other and are constantly struggling, with a guaranteed victory for our heroine, the BSF, who gets to eliminate 94 to 100% of the larvae of the house fly, using bird

Intensive dairy cattle breeding has a relevant social and economic impact in Portugal, particularly in the northern region. This activity generates a high flow of livestock effluents (slurry), rich in important nutrients for plant growth, which can be introduced into intensive production forestry systems. These effluents can provide a good alternative to mineral fertilizers, not only from an economic perspective but, particularly, from the point of view of environmental protection. In the present study, the effect of increasing doses of slurry on tree growth, either with or without mycorrhizal arbuscular fungi (AMF) and plant growth-promoting bacteria (PGPB) inoculation, was evaluated in clones of Paulownia CoT2 and Populus i214, as they are genotypes that have a high efficiency in the mobilization of soil nutrients (namely N) and in the capture of CO2 from the atmosphere, as well as high biomass calorific value. For this purpose, a demonstration field trial was installed, occupying an area of 14,607 m2, where the trees were planted with the compasses of: 2.5 x 1.5 m and 2.5 x 0.75 m, respectively for Paulownia and for Poplar. Prior to transplantation to the field, some plants were inoculated with AMF and PGPB. In the field, the following treatments were performed: T0 - no fertilization, either mineral or organic; T1 - amount of slurry equivalent to 85 kg of N ha-1; T2 - amount of slurry equivalent to 170 kg of N ha-1; T3 - amount of slurry equivalent to 340 kg of N ha-1, both with and without inoculation. Results revealed a significant and positive effect of the slurry application, both in the diameter at breast height (DBH) and total stand height (TH), showing its high fertilizing potential, and, on the other hand, there was no increased contamination by nitrates and by pathogenic microorganism in the leachates for the experimental doses of slurry. Therefore, we can conclude that, under the experimental conditions, the slurry resulting from the intensive exploitation of cattle constitutes an alternative to exclusively mineral fertilization in intensive production forestry systems, either by increasing the production of biomass or by the absence of contamination of aquifers by nitrates and pathogens.