Pedological studies of soils of the Tekapo set in East Lake Pukaki Region, South Canterbury, New Zealand

Abstract

Techniques were devised to map and describe the extremely variable soil pattern associated with moraines in the East Lake Pukaki Region. In such cases there arises a conflict between cost, utility, scale of mapping and purity of soil mapping units. Recent concepts of defining and relating soil profile classes to soil mapping units assisted in the choice of soil mapping units and facilitated concise descriptions of compound soil mapping units. Soil mapping units and soil profile classes were distinguished by means of a simple nomenclature. Soils of the Tekapo set were distinguished into four soil series. These series were described, and their genesis discussed in terms of environmental, morphological and chemical parameters. The major differences between soil series were attributed to difference in the covariant factors of age of soil development and soil parent material. Other factors discussed in terms of their importance to soil genesis included the effect of aspect, rainfall gradient, the rate of loess accumulation and the formation of fine textured subsoil bands. Soil properties indicated two periods of soil formation on former ground surfaces. It is predicted that these properties will allow the identification of comparable former ground surfaces in other areas. Predictions regarding soil fertility of the soil series are discussed. Land use capability units were devised and are superimposed on the soil map. The use of regression equations is discussed in regard to their use in classification and soil genesis studies. Classification of high country and upland sub-grounds of yellow-brown earths is discussed in relation to the series separated in this study and to other soils previously studies in Canterbury and Otago.