SOIL-LANDSCAPE MODELS AND SOILS OF EASTERN HIGHLANDS, PAPUA-NEW-GUINEA

Soil-landscape models of three landscapes representative of the Easter n Highlands, Papua New Guinea, have been developed and validated in a study area east of Kainantu. Soils were classified according to Soil T axonomy. Validation of a model in a strongly dissected landscape predi cted soils 88% correctly at Order level, 94% at Suborder and 88% at Gr eat Group and Subgroup level. Soils in weakly dissected landscapes wer e predicted 96% correctly at Order level, 92% at Suborder and Great Gr oup level, and 88% at Subgroup level. Soils on a simple alluvial terra ce system were predicted 100% correctly at Order and Suborder level an d 89% correctly at Great Group and Subgroup level. Soils of the strong ly dissected landscape are formed from an irregular cover of weathered tephra overlying weathered schist. They are mostly well drained Haplu dolls or Argiudolls on steep slopes with Troporthents on slipped slope s. Soils of the weakly dissected landscape are formed from thick weath ered tephra. Broad ridges and sideslopes are dominated by Argiaquolls, Argiudolls, Hapludalfs, Hapludolls and Humitropepts with dense concre tionary layers of iron and manganese. Soils of the terrace landscape a re formed from alluvium and vary from Fluvaquents and Endoaquolls to H apludolls. General nutrient trends of the soils of the strongly and we akly dissected landscapes show low levels of exchangeable cations, pla nt available phosphorus and zinc. Profile readily available water is l ow and clay mineralogy is dominated by kaolinite. Volcanic glass occur s in upper horizons of stable sites. Alluvial soils of the terrace lan dscape have higher nutrient values, particularly exchangeable magnesiu m.