This paper explains the concept of composted mounding, which is used to cultivate sweetpotato/kaukau ( Ipomoea batatas) in many locations in Enga province and parts of Southern Highlands and Western Highlands provinces of Papua New Guinea (PNG). It draws both from published literature and recent findings on sweetpotato cultivation in the PNG highlands. The practice of composted mounding allows permanent land use and intercropping, and facilitates successive multiple harvests of sweetpotato tubers and other vegetables. It counteracts the risks of frosts and soil-borne pests and diseases, and reduces soil erosion. It offsets the inherent soil-fertility problems associated with the dominant volcanic ash soils in the mounding zone of the PNG highlands. The method utilises locally available organic materials such as garden debris, weeds, grasses and farmyard manure as compost. Numerous agronomic trials have been conducted to evaluate the effects of composted mounding on sweetpotato yield. However, further research is needed on the decomposition process to assess the beneficial effects of mounding in terms of reduced risk of frost, and pest and disease damage, and to evaluate the benefits of using ever-greater rates of compost in the light of the extra costs of collecting the compost material.
