Use of geostatistics in designing sampling strategies for soil survey

Abstract

Semivariograms are used to quantitatively assess spatial variability of depth to mottles, depth to gravels, and thickness of loamy sand and/or coarser-textured layers, which are definitive criteria for classification of soils derived from alluvium on the Canterbury Plains near Lincoln College, New Zealand. Directions of maximum variation for depth to mottles and depth to gravels are NE-SW across an abandoned channel hollow. This pattern is reflected in the soil map of the study area and in the smaller-scale soil map of the adjacent region. Such variation reflects the past regional drainage patterns of channels flowing predominantly in a NW-SE direction. The appropriate field configuration of a sampling scheme for future survey of similar adjacent soils would be rectangular with a sample spacing in the direction of least variation k (anisotropy ratio) times that in the direction of maximum variation. -from Authors