Waste use in agriculture

Insect excrement as an alternative fertilizer for sustainable agriculture

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Picture by Dennis Kress

The mass breeding of insects for animal protein production could compete efficiently with conventional livestock to feed the ever-growing human population. Insect excrement (frass) is one of the main outputs of this process. In a recent review, scientist Poveda highlighted the benefits of reusing frass as bio-fertilizer in agriculture. Insect frass provides soils with nutrients, beneficial microorganisms and different biomolecules of great interest. Therefore it promotes plant growth and increases crop productivity for a sustainable agriculture.

Vermicompost for the sustainable management of crops pests and diseases

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Picture copyright Looseends (flickr)

Vermicompost originates from organic wastes decomposition by earthworms. This substrate and its liquid solution, vermicompost tea, enrich soils with essential nutrients and beneficial plant growth hormones and favor the development of microbes that suppress pests or diseases. Scientists Yatoo et al. recently reviewed how to produce these organic amendments and to use them for low-cost but efficient crop disease management. They reckoned vermicomposts are innovative eco-friendly alternatives to agrochemicals in crops and fruit production.

Cash for trash: recycling urban organic wastes as fertilizers

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Picture copyright Thuriès et al.

In sub-Saharan Africa, rapid-growing cities generate increasing volumes of organic wastes that can be recycled and transformed into organic fertilizers. Scientists Thuriès et al. found considerable variability and discrepancy in both agronomic and economic values of these wastes. Their results suggest that the composting process needs to be improved. They reckoned that the humus potential should be calculated to assess more accurately the amendment value and used to adjust their market price.

Vermicomposting to improve waste management and increase yields

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Picture copyright Compostador, Wikimedia

Vermicomposting is a process whereby earthworms transform organic residues into compost used as a growing substrate for plants. Scientists Blouin et al. recently showed that on average, vermicompost increased by 26% the commercial yield of cultivated plants. Cattle manure appeared the best original material, and the effect of vermicompost was stronger when no fertilizer was added.

Using insects to manage pre-consumer organic wastes

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Picture copyright Fowles and Nansen

Insects can be useful allies to sustainably manage organic wastes. They constitute also alternative sources of proteins and fats for humans. Scientists Fowles and Nansen recently reviewed the potential for using insects to convert wastes into value-added materials. After describing the “ideal insect bioconverter”, they conclude that targeted breeding of insects and their gut microbes is necessary to convert specific waste streams. More research is needed to explore the existing insect diversity and to identify new bioconverter species.

Improving composting with worms and additives

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Picture copyright Barthod et al.

Composting and vermicomposting are sustainable strategies for recycling organic wastes and producing organic amendments. Scientists Barthod et al. suggest that the presence of worms in combination with additives significantly improves the composting process. Co-composting strategies need to be locally optimized, involving the generated amendments in a circular economy suitable to improve sustainability of agricultural systems.