*3.2. Supply Chain Logistics*

Fresh fruits and vegetables sold in the Honiara municipal market were primarily sourced from farms located to the east of Honiara, and to a lesser extent, villages on the north–west of Guadalcanal Island (Figure 2). Products sourced from farms located to the west of Honiara were more common during the November sampling period. Few farms located in the southern parts of Guadalcanal supply the Honiara municipal market. A small percentage of Honiara municipal market vendors (8.7%) were sourcing produce from Malaita, Gizo and Savo Islands (Figure 2). Inter-island sourced products were only observed in the Honiara municipal market, with the road-side markets tending to source locally-grown products.

**Figure 2.** The locations (green marked areas) of farms supplying the Honiara municipal and road-side markets during the survey period (November 2017 and March 2018 data combined). (Source: Base map: Popgis@spc.int Solomon Islands National Statistics Office, Solomon Islands, 2018). Note location of farms are not GIS positioned.

Horticulture transport logistics into the Honiara municipal market were relatively short, with products travelling 40 to 47 km (Table 4). In comparison, products supplying the road-side markets travelled 19 to 27 km, almost half the distance. Some of this disparity can be attributed to the inclusion of inter-island supply chains into the Honiara municipal market. When the median transport distances are considered, the transport distance between farms and municipal markets or road-side markets were relatively similar in the November 2017 survey. In the March 2018 survey, mean transport supply distance for road-side markets was 17.1 km (Table 4). This reduction in transport distance implies vendors are able to source more products locally, and may explain the lower incidence of postharvest loss observed in road-side markets during this time (Table 2).


**Table 4.** Transport distance from the farm to the municipal or road-side markets.

<sup>z</sup> Road-side market data represents data sourced from the Henderson, Fishing Village, Lungga, King George VI and White river road-side markets.

The mean transport distance for the individual road-side market network varied depending on the market location and the survey date (Table 5). Products sold at the Lungga and King George VI markets tended to be sourced from smallholder farmers located in close proximity to these markets (1 to 2 km away). Whereas products supplying the larger White river and Fishing village markets travelled 24 to 37 km. The comparatively shorter transport distances for the White river noted in the November survey and for the Henderson and Fishing village markets in the March survey are thought to reflect possible crop seasonal variability in the supply chains.


**Table 5.** Mean transport distance from the farm to the individual road-side markets.

The most common mode of transport used by farmer/vendors to transport product to the Honiara markets (municipal and road-side) was by truck (Table 6). Truck-based transport systems were associated with farms located in more remote intra-island locations, with a mean travel distance of 37 km. However, there was considerable variability in transport distances involving trucks, with the shortest recorded transport distance being 6.2 km and the furthest being 64.8 km.

**Table 6.** Mode of transport used and mean transport distance for all markets and all survey dates.


<sup>z</sup> Values followed by the same letter are not statistically different at *p* < 0.05 based on Tukey–Kramer test.

Mean transport distance involving cars or minivans/public buses was 20 to 25 km (Table 6). There was also considerable variability in the transport distance by car—ranging from 3.7 to 44.7 km, and transport distance by minivan/public bus—ranging from 0.5 to 41.2 km.

Transport by taxi was limited to farmers located relatively close to the market, with a mean transport distance of 8.5 km (Table 6).

## *3.3. Potential Contributions to Postharvest Loss*

There was a weak correlation between transport distance and postharvest loss (Figure 3). Farms with very high levels of postharvest loss (>30% loss) were primarily located within 50 km of the markets. Conversely, most supply chains with a transport distance of 100 to 200 km had less than 10% loss.

The location of farms with moderate (10 to 19%) to very high levels (>30%) of postharvest horticultural loss are shown in Figure 4. Elevated postharvest loss was more prevalent in supply chains sourcing products from the far eastern part of the main production center (see Figures 2 and 4). There were multiple supply chains sourcing products from Tutumu, Tenaru, Vatukukau, Ruavatu, Siara, Binu, Aola, Tasimboko, Dadai villages on Guadalcanal Island, and Matakwara and Buma villages on Malaita Island with moderate to very high levels of postharvest loss. While there are relatively few farms located on the southern and far western parts of Guadalcanal supplying the Honiara markets (Figure 2), none of these had elevated postharvest loss (Figure 4).

**Figure 3.** A linear regression analysis of percent postharvest loss verses transport distance for all vendors, markets and survey dates (n = 346). R2 = 0.2503.

**Figure 4.** The locations of farms supplying the Honiara municipal or road-side markets with elevated levels of postharvest loss. (Source: Base map: Popgis@spc.int Solomon Islands National Statistics Office, Solomon Islands, 2018). Note farm locations are not GIS positioned.

The type of products being sourced by market vendors differed depending on farm location (Figure 5). Inter-island supply chains and those chains sourcing from the remote farms on Guadalcanal Island were less likely to include vegetables. Vendors instead tended to source vegetables from closer proximity intra-island located farms, especially those in the "greater Honiara" region and north-eastern Guadalcanal.

The most commonly sourced product from remote farms (>50 km) was watermelon, green banana and English cabbage (Table 7). Highly-perishable crops sourced from remote farms on Guadalcanal tended to be higher-value Asian leafy vegetables such as Pak choi and Choy sum (Table 7). Mean postharvest loss for these chains was 13.2% with half the consignments incurring ≥20% loss (data not shown).

**Figure 5.** The commodity composition (vegetables to fruits ratio) of consignments sourced from intra verses inter-island located farms. (**A**) Intra-island supply chains (Guadalcanal) into the Honiara market; (**B**) Inter-island supply chains into the Honiara market. Data is based on number of consignments, rather than consignment volume or weight.

**Table 7.** The most common commodities being sourced by vendors at the Honiara municipal market from remote located farms (>50 km from farm to market).


A wide range of different packaging types were observed in the markets (Table 8). Large sacks (≥40 kg) were the most common type of packaging, especially for leafy indigenous vegetables. Higher value crops such as tomato and Asian vegetables tended to be limited to smaller (<20 kg) packing units. Postharvest loss was highest in very large packing units (Table 8).



<sup>z</sup> Values followed by the same letter are not statistically different at *p* < 0.05 based on Tukey–Kramer test. <sup>y</sup> Vendors also used a range of other packaging options: plastic trays (14.2% of vendors), small plastic bags (5–10 kg) (10.5%), plastic crates (1.5%), plastic buckets (3%), steel basins (8.4%), locally woven baskets (1.5%) and nil packaging (1.5%).

#### **4. Discussion**

Horticultural postharvest loss in the Honiara municipal market was 7.9 to 9.5%. In comparison, postharvest loss in the Honiara road-side markets tended to be lower (2.6 to 7.0%) but more variable. This level of loss was consistent with other South Pacific municipal markets, with Reference [19] reporting a 6.2% loss in the central municipal market in Samoa. Most municipal market vendors in Honiara experienced some level of postharvest loss, whereas road-side market vendor loss tended to be less common. Based on mean postharvest market loss and the incidence of individual vendor loss, Honiara's road-side market system appears to be more effective in minimising postharvest loss, compared to the municipal market.

The potential contributors to postharvest market loss in Guadalcanal markets and reasons for reduced loss in the road-side markets are likely to be multifaceted. Diverse market participation (commercial-scale farmers through to semi-subsistence farm surplus), poor road infrastructure, the lack of a cool chain, limited or poor packaging, and inadequate market storage facilities needs to balance against potential supply chain practices that seek to mitigate or lessen potentially elevated postharvest loss. While the contributors to generic postharvest loss in horticultural markets have been widely reported [19,21–24], the inclusion of possible vendor or farmer strategies to reduce this loss are often overlooked.

Intuitively, it would be logical to assume that transport distance would have a significant effect on the level of postharvest loss seen in the market, consistent with the findings in other postharvest supply chain studies [24,25]. While inter-island supply chains appear to have higher levels of postharvest loss compared to intra-island chains, we found that postharvest loss was poorly correlated to transport distance. Farms with very high levels of postharvest loss (>30% loss) tend to be located within 50 km of the markets, most supply chains with a transport distance of greater than 100 km have less than 10% loss, and loss associated with very remote intra-island supply routes was similarly less than 10%. These observations would suggest that the distance horticultural produce needs to travel from the farm to market is not a good indicator of potential market postharvest loss in Guadalcanal.

The type of crops sourced from inter-island and remote intra-island farms and their associated supply chain practice may provide some insight into the disconnect between transport distance and postharvest loss. Most inter-island supply chains included in this study were dominated by semi-perishable crops such as watermelon, pineapple and citrus. Such crops are often considered to be more tolerant of challenging transport logistics and potentially prolonged market storage. In the more remote Malaita to Guadalcanal inter-island supply chains, the product was sourced from two fruit production centers, watermelons from Buma and pineapples from Bina. These chains involved commercial-scale farms with relatively predictable transport logistics, with resultant postharvest loss being relatively low (<5%). Georgeou et al. [11] reported that the most commonly traded crops from Savo and Nggela Islands into the Honiara markets were fruits, nuts and root crops. In remote intra-island chains, such as products sourced from Mbalo on the far south-eastern part of Guadalcanal and Tangarare on the far south eastern part of Guadalcanal, there was a similar dominance of semi-perishable crops such as watermelon and citrus. While this might simply reflect local agronomic production conditions favouring certain crops, it is also possible that there is deliberate strategy by farmers supplying the Honiara market to avoid highly perishable cash crops if the associated transport logistic is likely to incur high-levels of postharvest loss.

Vegetable supply chains still represented a significant portion of the overall inter-island trade into Honiara. A recent study of the Savo to Honiara market supply chains [16] reported not only semi-perishable crops but also highly perishable leafy vegetables being traded. Savo farmers indicated high levels of postharvest loss due to in-transit damage and delays in accessing transport [16], even though Savo Island is only about 35 km from Honiara. The presence of inter-island trade of perishable vegetable crops in spite of high-levels of postharvest loss is interesting. Georgeou et al. [16] reported that much of the trade from Savo Island into the Honiara municipal market was due to opportunistic market participation due to surplus local production [16]. Faced with possibly few alternative local market opportunities on Savo Island, potentially high postharvest loss does not appear to disincentivise market participation.

When intra-island vendor loss was analysed in terms of where produce was grown, we found that there was a cohort of villages in the western and southern parts of the main horticultural production (which is located in eastern Guadalcanal) which were consistently associated with atypically high levels of postharvest loss. This result might reflect the type of crops grown in these locations, with Reference [11] reporting that most of the perishable leafy vegetables sold in the Honiara municipal market were sourced from farms located in north-eastern Guadalcanal. An alternative or additional possibility is a lack of reliable commercial transport options in these villages, or generic poor harvesting

and handling practice. Further studies are required to better understand on-farm postharvest practice and supply chain logistics within these villages. Spatial mapping of high-loss postharvest chains has not been previously reported in the South Pacific, and provides useful information in terms of helping to better target possible future technical farmer assistance and supply chain remediation.

Supply chain modes of transport associated with Honiara's markets reflect the diversity of agronomic production systems, from the commercial-scale through to semi-subsistent trade farm surplus. The most common form of transport was open trucks, consistent with the findings reported by Reference [11]. Nearly all of the supply chains sourcing products from eastern Guadalcanal were dependant on trucks, possibly reflecting the volume of trade, poor road conditions and some level of local transport coordination. In Samoa and Vanuatu, where there is a relatively well maintained road-network and small production volumes, public buses, minivans and private vehicles are more commonly used [19]. While the mode of transport is interesting, the specific postharvest transport conditions need to be better understood. How crops are loaded and the load configuration within the truck, the volume being transported, other possible items being co-transported can also have a significant influence on postharvest loss. More work is required to better understand transport logistics especially between eastern Guadalcanal and the Honiara markets as a possible contributor to postharvest loss.

A range of packing types were used by farmers, the most common of which was 40 kg of woven sacks. Given the large diversity of crops and packaging options, only a superficial assessment of the implication of packaging type on loss could be undertaken. As anticipated, very large agricultural sacks (>100 kg) used transport traditional leafy vegetables incurred significantly high levels of postharvest loss compared to smaller sizes of the same packaging type. Most heavy produce (such as pineapples, watermelon) were transported loose (no packaging). In the case of pineapples, the product was often tied into bundles of up to 40 fruit and carried using wooden poles. Plastic crates were rarely observed. Plastic buckets and steel trays were used for crops prone to damage during transport (such as tomato and papaya). The packing options used by farmers and vendors is thought to simply reflect the type of packaging readily available, with Reference [23] noting that vendors in Malaita Island were aware of the adverse implication of poor packaging.

Comparatively low postharvest loss (4 to 5%) associated with a commonly used form of packaging (i.e., woven sacks ≤40 kg) would suggest that while packing is far from ideal, for most farmers packing had little effect on resultant postharvest loss. However, damage associated with poor packaging can be latent and, therefore, not immediately evident when product arrivals at the market. Georgeou et al. [11] reported that product in the Honiara municipal market is commonly sold with 1/2 to 1 day or arriving at the market. It is possible that the potential full implications of poor packaging may be somewhat negated due to rapid market-throughput.

How efficiently the market-to-consumer food system operates directly influences postharvest supply chain loss. Noting high tropical ambient conditions, prolonged market storage has been reported to significantly elevate postharvest loss in other Pacific horticultural markets [19]. The observation by Reference [11], that most vendors in the Honiara municipal market sell their produce within 1/2 to 1 day is therefore significant. Honiara's road-side markets are likely to experience even more rapid product throughput due to fewer vendors and smaller volumes of product being sold, reducing vendor competition, and road-side markets located close to the resident's areas increasing potential consumer accessibility. In comparison, a product traded through the municipal market in Samoa is often stored for 2 to 3 days before it can be sold [19]. In Samoa, the benefits of comparatively good on-farm postharvest handling practice and shorter transport distances are being undermined by prolonged market storage [19]. In the Honiara markets, rapid market throughput of a perishable product is thought to be an important factor in avoiding potentially higher-levels of postharvest loss due to poor on-farm and transport practice. Fast on-selling by vendors in the Honiara municipal market is not the result of a better designed market infrastructure. Instead, high market vendor fees, over-crowding, poor market storage conditions, and significant concerns over vendor safety and

hygiene create tangible incentives for Honiara vendors to sell their produce as quickly as possible. Further studies are required to better understand road-side market trading practices and whether this further contributes to slightly lower postharvest loss in these markets. The implications of current vendor practice on postharvest loss at the consumer-end of the value chain also warrants further investigation.

One variable that needs to be considered when interpreting market survey data in this study is the potential for inter-market trade (particularly between the Honiara municipal market and the various road-side markets). Georgeou et al. [11] reported that approximately 30% of consumers at the Honiara market were on-selling products in other markets. In this study, we sought to exclude vendors who had sourced products from other markets from the survey, however, 2.6% of market vendors surveyed were unable to identify the farm location where the product was sourced. However, given that Reference [11] further highlighted ongoing tension between farmer vendors and re-sellers, suggesting that re-sellers may not self-identify when surveyed, we cannot exclude the possibility of some level of data error based on vendors providing deliberately inaccurate survey responses.
