Cash for trash: recycling urban organic wastes as fertilizers

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

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

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

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.