Food Waste: Quantifying on-farm vegetable losses

Of the fields sampled, each provided unique results, as the conditions for production, harvest, and marketing were individual to the crop and harvest date. Field size averaged 6.75 acres, and ranged from 2.5 acres to 14.75 acres. The size of the sample taken in each field represented between 0.13% and 0.90% of the total field area.

Sorting the produce collected from the three sample rows into the categories of marketable according to the growers’ specifications, edible but currently unmarketable (EBU), and inedible due to disease, damage, or over-maturity provided a clear picture of the quality of produce remaining in the field. Scaling up from the volume found per plant using the adjusted plants per acre provides an estimate of the volume remaining per acre. Marketable volume remaining averaged 2,595 lbs per acre over all fields sampled. Edible but unmarketable vegetables remaining averaged 5,292 lbs per acre.

Current figures in food loss and waste are often reported in estimated percentages, and farm-level losses for fruit and vegetables are most commonly considered to be 20% of the marketed yield (Gustavsson et al., 2011). Five fields of the thirteen evaluated contained marketable produce in amounts greater than 20% of the harvested and marketed yield, including all four cucumber fields and one of the squash fields. All of the fields evaluated contained produce that was considered edible but would not meet buyers’ specifications, representing amounts greater than the harvested and marketed yield. Six fields contained edible but unmarketable volumes in amounts greater than 40% of the grower’s yield, including three cucumber fields, two zucchini fields, and the eggplant. What is unclear throughout related studies based on estimates from grower interviews, is whether the estimates growers have provided account for only marketable produce, or all produce that is suitable for human consumption. Combining the marketable and edible portions of the remaining produce found in this study reveals much higher percentages may be lost at the farm level than previously thought (Figure 1). Considering all of the crops found to be of wholesome edible quality in the fields evaluated, the percentage of losses ranged from 12.2% of the harvested yield in one of the squash fields, to 142.7% in one of the cucumber fields, and averaged 57%.

It is important to understand that in the case of postharvest losses, estimates from the 1970’s and 1980’s are frequently carried forward in literature as modern estimates (Parfitt, 2010). Decades of innovation in plant breeding, irrigation, plant nutrition and other areas have made production more efficient. At the same time, the potential exists for the current market-driven system to have become more or less wasteful over time. The grower in this study also assumes a 20% loss including both the field and packing house, but orders supplies and packaging based on a 15% loss.

Using field sampling provides a concrete starting point for estimation, rather than beginning with a grower’s visual estimate of what remains in the field. This technique overcomes the limitation of underestimation that may occur when reporting. Additionally, using a standardized method across many crops allows for a metrics that can be compared to be utilized, such as pounds per acre. Field sampling is considered to be a good choice of method when losses are unknown (Franke et al., 2016) and methods are needed to support monitoring losses (WRAP, 2017).

One published study has undertaken field sampling to determine the volume of losses occurring in commercial production of vegetable crops in developed countries. A study of lettuce produced in Sweden determined through field sampling of five farms that an average of 2,855 pounds per acre (converted unit) of lettuce heads remained in the field after the primary harvest, in addition to a much larger amount of outer leaves (Strid and Eriksson, 2014; Strid et al, 2014). The study used three sample areas on each farm to determine the remaining crop per square meter, then scaled the data up to the hectare (Strid and Eriksson, 2014).

Again, combining the marketable and edible volumes found after the primary harvest, the volumes suitable for recovery are potentially vast (Figure 2). Volumes ranged from 1,385 lbs per acre in squash to 19,766 lbs per acre in eggplant, and averaged 7,887 lbs per acre. These volumes exceed the lettuce study’s findings, and no other published studies exist for comparison. 

The remaining volume in the field that was considered to be marketable according to current buyer specifications for quality averaged 19.17% of the yield that was marketed from the farm, closely mirroring the 20% usually reported as a national estimate. This commonality again raises the question, are reported losses that are estimated by growers and others simply taking the marketable portion into account? Additionally, this provides strong evidence of how yields could be raised immediately, without increasing the use of land or chemical resources. However, continuing the harvest would require increased demands on labor, and an increase in farm labor costs. With pressing demands in other fields, labor efficiency dropping because of high quality is harder to find in the field, and prices that provide a slim margin for profit, the grower must balance priorities, which can include leaving a portion of the marketable crop unharvested.

Solutions that provide more opportunity to profit from the entire crop produced, and solutions that improve fresh produce recovery efficiency are needed. Godfray et al. (2010) call for “radical” changes to the way food is produced, similar to “those that occurred during the 18^th- and 19^th-century Industrial and Agricultural Revolutions and the 20^th-century Green Revolution.” Through many innovations in the way crops are produced, vegetable yields have grown. However, further utilization of crops that are edible but may not meet current buyer standards for quality can increase the available supply of fresh produce in the US by an estimated 20%, without increasing the amount of some of the resources used in their production.

Results from field sampling and scaling can provide growers with more information to make decisions on whether or not to continue the harvest. While the data collected for this case study represents a single time point in the life of each field, it has confirmed that wide variability occurs at the field level, and that estimates derived from historical data or interviews could be made more reliable with corroboration through field sampling. This project has outlined an efficient method for growers, recovery organizations, markets interested in purchasing produce, or government agencies to use in order to measure and further understand the volume of losses occurring on vegetable farms, and has demonstrated its practical usage on one farm.

Field evaluations for this case study have shown that the volume of marketable food remaining in the field can be high in comparison to the marketed volume, which could provide opportunity for growers to further profit from the crop they are already cultivating. Additionally, the volume of food that could be recovered for human consumption was much higher than the estimates discussed in previous studies, revealing the potential for recovery organizations to procure even more healthy food. Further research on the amount, types, and reasons for food loss at the farm level has been repeatedly recommended, and this study confirms that it is needed.