Soil types and traditional soil management in the Purari catchment.

Abstract

The soil pattern of the Purari catchment (Papua New Guinea) is greatly influenced by the distribution of volcanic materials, particularly volcanic ash. Volcanic ash soils are the most important soil type in the catchment occupying the largest area and supporting a large and diverse agricultural popuplation living mainly in the highland valleys. Soil degradation has been a problem in the catchment for 1000 yr, although evidence suggests that this has accelerated, particularly in the period since European contact. Rapid population growth and limited cultivable land, particularly in the highlands, are causing increased pressure on land resources. Gardens are being fallowed for periods too short for the soil to regain its fertility.-from Author