Soil-landscape models as a basis of land resource assessment Flock Hill Station, Central Canterbury, New Zealand

Abstract

A methodology for using physiographic analysis and soil-landscape models to apply nationally available data to land resource assessment at the property level is outlined. The analytical procedure promotes the sequential analysis of existing data, air photo interpretation, selective field work and sampling. The method reduces operational costs, provides semi-quantitative fertility data, and improved assessment standards. Resources are targeted onto areas with greatest agronomic potential. Emphasis is given to those criteria recognisable in the field and on aerial photographs. The technique complements the present land resource data base. Detail and variability within existing mapping units is documented, and field relationships are illustrated.

A case study from Flock Hill Station, a property representative of the eastern South Island intermontane basins is presented. Rock type(s), soil-landscape model(s), soil form(s), mapped soil set(s) and land use capability class(es) for 114 physiographic units are recorded. Eleven dominant soil-landscape models are reviewed. Field relationships are illustrated within 8 representative windows at scales of 1:20,000, and 1:13,000. Twenty soil forms and 19 soil form classes reflecting stage of soil development, soil fertility status and hydrological regime were recognised. Soil forms were differentiated on the following key criteria; soil horizon sequence, B horizon colour and hue, soil redox, texture, and structure profile form, solum depth, landform, and parent material, and are supported by soil fertility quick test data. The 20 soil forms are correlated to one of seven mapped soil sets.

The method is used to identify favourable sites for intensive management and development, in combination with stratified soil sampling and quick test analyses. Utilisation of MAF fertiliser models to calculate pasture maintenance and establishment requirements are also illustrated.