Constraints faced by supply chains

 By Isidora Ramita and Eleo Dowa

Sweet potato is the main staple crop grown by subsistence farmers in Papua New Guinea. 

It is an important fresh produce sold in rural and urban markets and remains competitive with other foodstuffs. 

It is a favoured item for daily household meals apart from rice and other staples such as cassava, taro and banana. 

Today consumers prefer sweet potato grown in the Highlands region. 

The domestic market for highlands sweet potato was initially limited to local and urban markets. 

However, an increasing number of farmers in the Eastern and Western Highlands provinces are producing sweet potato as a commercial crop for sale at distant coastal markets in Port Moresby, Lae, Madang, Kimbe, Alotau and Rabaul. 

The domestic market for sweet potato is considered to be an important income avenue for smallholder farmers. 

The marketing of sweet potato is affected by supply-side constraints including lack of sorting facilities, poor packaging and handling, poor roads and transport services, poor storage and market houses, lack of market information and high cost of doing marketing. 

These constraints contribute to reduced returns to the farmers’ pocket. 

Moreover, post-harvest losses of sweet potato occur from farm to market and reduce the quantity and quality of saleable fresh produce.

A recent mapping study of sweet potato was carried out by the National Agricultural Research Institute (NARI) and Fresh Produce Development Agency (FPDA) and funded by the Australian Centre for International Agricultural Research (ACIAR). 

The study mapped the supply chain of major sweet potato farmers from Eastern and Western Highlands provinces to coastal markets in Lae and Port Moresby. 

The study found that problems along the supply chain from farmer fields to markets had severe impacts at the distant markets such as Lae and Port Moresby. 

These included:

• Improper harvesting, careless packing, poor packaging and transport conditions, poor handling, and lack of proper storage facilities allowed considerable postharvest losses (refer to figure).

For example, over-packing of bags in the garden and high temperatures during transportation led to higher percentage of damage of the sweet potatoes. Numerous handling during loading and unloading at each transit points resulted in much damage. 

Rot and disease affected sweet potatoes arriving by road at Lae’s Main Market. In Port Moresby there were higher incidences of rots and diseases of sweet potato in the bags.

• The absence of appropriate storage facilities meant that even undamaged sweet potatoes in over-packed bags could very easily deteriorate. 

Damage and disease as a result of poor post-harvest practice reduced the quality, which caused a problem in marketing sweet potatoes.

To minimise post-harvest handling errors of sweet potatoes farmers should use small packaging options such as 20kg-sized bags so that it is easy to handle, find ways to stabilise the crop during transportation, educate each actor along the supply chain, develop quality descriptors to define locally-appropriate grades to promote price premium and incentive for quality improvement, improve infrastructure for transportation (possibly a cool chain) and pre- and post-harvest storage by government agents.