A study of soil variability within the Blackball Hill soils, Reefton, New Zealand

Abstract

Soil variability within the Blackball hill soils was investigated in some small catchments near Reefton. Soil-landscape relationships within this area were assessed and summarised in terms of a generalised model. Techniques were devised to map and describe the extremely variable soil pattern. Recent concepts of defining and relating soil map units to soil profile classes and landscape bodies were found to be particularly useful in establishing map delineations. Three such delineations were distinguished, and although based on landscape features and morphological evidence, they were generally supported by differences in measured soil parameters. Variations in pH, bulk density, particle size, oxidisable carbon, total nitrogen and phosphorus, poorly-ordered forms of aluminium and iron, and clay mineralogy were shown to support the concepts of translocation of materials implicit in both the soil catena and soil landscape systems models. Clay mineralogical data indicated that alternative weathering cycles could replace each other as pH values, and organic matter levels, altered during the course of soil development.