The Effects of Shifting Cultivation on Soil Properties: An Example from the Karimui and Bomai Plateaux, Simbu Province, Papua New Guinea.

Abstract

The analysis of soil samples removed from both rainforest and subsistence food gardens on the Karimui and Bomai Plateaux revealed that shifting cultivation has a marked effect on soil chemical properties. With cultivation there is a reduction in available P, exchangeable Ca and Mg, cation exchange capacity and %C and %N. The decline in soil fertility with cultivation is thought to be due mainly to a reduction in soil organic matter resulting from the clearance of the rainforest vegetation. The likely effects of resettlement are discussed, and it is thought that only about 5500 people could be resettled on the plateaux under the existing system of shifting cultivation. A further increase in population would require more intensive cultivation techniques to be developed, and these could result in soil deterioration and environmental disturbance.