Understanding Post-Harvest Losses

According to FAO estimates, approximately 1.3 billion tonnes of food gets lost or wasted every year around the world. These losses occur all along the food value chain, from farm to fork, and understanding exactly where they occur for specific commodities and in specific geographic locations can go a long way in helping researchers and policymakers design interventions to reduce them. Such a reduction in food loss is an important part of the Sustainable Development Goals, specifically SDG12.

A new IFPRI Discussion Paper examines post-harvest losses for maize, soy, and groundnuts at the farm-level in Malawi. The study, which encompassed 1,200 households during the 2015-2016 growing season, involved a detailed questionnaire that asked farmers to self-report about crop losses during harvest, transport, processing, and storage of these three staple commodities. The questionnaire addressed both total crop losses and reductions in crop quality.

The results show that post-harvest losses in these three major crops affect many of the surveyed farmers, but were far from being equal across the board. For maize, 28 percent of households reported a loss of quality during the 2015-2016 season, while 26 percent reported a total loss and 36 percent reported a loss of any kind. For groundnuts, these numbers were 37 percent, 33 percent, and 47 percent, respectively; for soy, they were 29 percent, 34 percent, and 42 percent, respectively.

About 30 percent of the reported maize and groundnut harvests was classified as having “very little damage”; around 20 percent was classified as having “extensive damage”, and around 40 percent was reported as being “completely lost”. For soy, the percentage of the harvest that was reported as being completely lost was even higher, at 52 percent. Only 22 percent of the soy crop was reported as having “very little damage”.

The study also found that the harvest stage and the processing stage appear to incur the most losses. Forty-three percent of maize losses occurred at harvest and 37 percent during processing; for groundnuts, those numbers were 49 percent and 35 percent, respectively. For soy, 58 percent of losses occurred during processing and 36 percent occurred at harvest. Interestingly, the storage stage saw relatively low losses: 21 percent for maize, 16 percent for groundnuts, and only 5 percent for soy. According to the study authors, the low levels of loss seen during storage may due to the fact the survey was conducted relatively soon after the harvest, and so storage losses may continue to accumulate over time.

In terms of the actual quantity (in kilograms) of crops lost, the study looks at both unconditional proportions of total harvest and conditional proportions of total harvest. The unconditional proportions – the mean quantity (in kg) lost – were 5 percent for maize, 5 percent for groundnuts, and 3 percent for soy. The conditional proportions – the mean quantity lost if any loss – were 5 percent, 12 percent, and 8 percent, respectively. The paper reports that these conditional proportions are well below FAO estimates, but that losses of 5-12 percent of their harvests could be significant for many small-scale farmers.

Farmers reported the most important causes of loss during harvest and transport to be loss by handlers, weather (particularly humidity and rain during and post-harvest), mode of transport, and timing of activity. During processing, the most important causes of crop loss were reported to be crops blowing away (particularly for soy), crops being spilled, rodents and other animals, and improper processing methods. During storage, rodents and pest infestation are the main causes of crop loss.

The study also asked questions regarding how damaged and undamaged crops are used. Undamaged crops were used primarily for sale and for seed; damaged crops, on the other hand, were much more likely to be consumed by the household.

The paper concludes with several policy implications. First, since most of the losses found in the study appear to be concentrated in the harvest and processing stages, efforts should be made to target activities in these stages. Second, efforts need to be made to properly educate farmers regarding both the benefits of technologies to reduce post-harvest losses and the conditions, such as wet weather, under which they should be most concerned about loss prevention. Such education could increase the effectiveness of interventions to reduce post-harvest losses.

Finally, the authors highlight the need for further research, particularly regarding post-harvest losses among middlemen and processors, in order to determine whether interventions targeted at these actors could cost-effectively enhance crop handling, reduce loss and waste, and improve overall food availability in Malawi. 

By: Sara Gustafson, IFPRI

Photo credit:Twin and Twin Trading