 Mounds above 2,500m in altitude can have a height of 0.85m in height; while crops below 1,500m are not mounded at all (Dove and Carpenter 2008).The function of the mound is to protect the crops from the frequent frosts that occur at the high altitudes of the Enga.With sweet potatoes having a very long maturation period, 9 months, the Enga also invest their time and space on the mounds with planting other crops that have much shorter maturation periods such as peas in case a heavy frost does claim the crop (Wohlt 2004).