When we think about how to feed an estimated 8.5 billion people by 2030, a natural first reaction is: we’ll have to grow more food. But in reality, about one-third of all food produced for human consumption is lost or wasted — roughly 1.3 billion tons of food per year. Reducing this postharvest loss would help ensure everyone has enough to eat.
Postharvest loss can be caused by a host of factors: pests, diseases, unexpected rain during drying, poor harvesting or storage techniques, disrupted transportation routes, even poorly considered policies.
For example, in some regions of sub-Saharan Africa, farmers and traders pay per sack, rather than by weight or volume, to transport their crops to markets.
“So you’d see farmers and traders create these huge extended sacks, sometimes over two meters high, to avoid costs. If you have a freshly harvested crop, such as sweet potato, in those massive sacks, inevitably some gets crushed and that leads to higher losses,” said Tanya Stathers, Associate Professor of Sustainable Agri-food Systems at the Natural Resources Institute (NRI) of the University of Greenwich.
“There’s a vast, complex and diverse range of problems that lead to postharvest loss.”
Stathers leads the Reducing Food Loss research team for Ceres2030, an initiative of Cornell University, the International Institute for Sustainable Development, and the International Food Policy Research Institute. The Ceres2030 teams have undertaken massive, systematic reviews of literature on interventions that can support smallholder farmers in low and middle-income countries, with the aim of providing a solid evidence-base to inform decision-making to achieve the United Nations Sustainable Development Goal of ending world hunger by 2030.
Reducing food loss team
Stathers’ team, which includes seven researchers and two librarians from four continents, analyzed interventions for reducing crop postharvest loss for the major crop groups: cereals, legumes, root and tubers, fruits, and vegetables. They focused on loss reduction interventions for 22 of the most important food crops consumed in sub-Saharan Africa and South Asia, and created a database of their findings, searchable by country and crop.
Their review quickly made clear that there has been an abundance of research on maize, and not nearly enough on any other food crops.
“Maize is a very important staple food across sub-Saharan Africa, and it is vitally important that we work towards reducing losses of it during and after harvest,” Stathers said. “But we also need to look beyond just the calorie-rich crops, and recognize the nutritional and socio-economic importance of other food crops.”
Like all of the Ceres2030 teams, the Reducing Food Loss team wanted to focus on identifying those interventions that had been tested at a real-world scale, to see which interventions were effective for farmers and other players in the value chain, such as traders and transporters. They started out with almost 13,000 articles, then whittled down to 334 that met their criteria. Surprisingly, only 30 percent of those studies involved community members in testing the interventions.
“That’s an area that needs much stronger emphasis, because what works well under researcher management may not work as well under farmer management,” Stathers said. “In addition, that’s a lost opportunity for training, for two-way learning, and for understanding what helps and hinders adoption of loss-reduction interventions.”
Another core finding was that much of the postharvest loss reduction research has focused on technologies. There’s some good reason for that — many technologies, such as hermetically sealed containers, effectively reduce losses. However, despite considerable donor investments in hermetic bags, very little of the grain grown in the study’s focal regions is yet stored in such containers.
“Nearly all of the attention has been on tangible technologies, and there are no studies on how changes in policy or access to finance or training help reduce losses. There’s only one study on how improved road infrastructure affects transport losses in perishable crops,” she said. “Our study synthesized the existing evidence-base and highlighted those interventions which effectively reduce losses in the different food crops. However, it also recognizes the need for study of a broader range of crops, that widens the focus beyond storage losses, and increases understanding of how different types and combinations of interventions can reduce losses.”
Brighton Mvumi is Professor of Postharvest Science and Technology and Chair of the Department of Agricultural and Biosystems Engineering at the University of Zimbabwe, and a member of the Reducing Food Loss research team. Mvumi said postharvest loss reduction is a critical and underappreciated dimension of the food system, with serious social, economic, and environmental implications.
“I strongly believe that it is a travesty of ethics to lose food when others are hungry,” Mvumi said. “In the past, investment has largely focused on crop production with very little being channeled towards postharvest management.
It is cheaper to prevent food loss than to produce the lost quantity.”
Mvumi urges donors and governments to consider supporting investments such as: infrastructure like packhouses and cooling facilities; equipment for harvesting, processing, cleaning, and packaging foods; stakeholder and postgraduate training to build capacity; and incentives for private sector involvement to ensure sustainability of postharvest loss interventions.
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