Spatial distribution of soil properties relevant to the sustainable production of cotton in the lower Namoi Valley

Date Issued:1994-06-30

Abstract

The anisotropic nature of the soil continuum does not lend itself to classification schemes constructed as many are by predetermined hierachical classes. Membership to classes are hard and are hence unable to consider the reality of the continuum, which ultimately manifests itself in the resultant soil map which delineates areas of supposed similarity. Further, the soil profile acts as the individual which itself varies vertically, with depth. In the following report the rather novel approach of fuzzy classification or continuous classification is used to classify individual soil layers from the lower Namoi Valley in an attempt to better represent the anisotropy of the soil continuum. Essentially 1419 chemical soil layers with particle siza analysis data taken from specified depths within 227 soil profiles were classified using fuzzy kmeans. Ten soil layer classes or clusters were identified within the data, which were then reclassified to consider an additional extrade layer class or outlier class. When reassembled into their constituent profiles the layers from these classes formed readilly identifiable profile sequences which were classified accordingly. The resultant proflies once mapped corellated well with field perceptions of the geology and geomorphology of the lower Namoi Valley. As with the classificatory difficulties associated with soil classification many land evaluations are constructed in a similar fashion in which subjective cut offs are used to delimit areas or tracts of land which are better suited than others. Continuous classification was applied to a quantitative land evaluation introduced for New South Wales for wide variety of land utilisations by using a function which by its nature produces a continuous membership between two classes, suitable and non suitable to any particular land utilisation. The following report illustates the potential of such a classification scheme which could be used in a number of disciplines where the continuous nature of a medium can be expressed and has potentially many practical applications. As a consequence of the work undertaken and presented within this report new directions and technologies are suggested which could be undertaken for further research

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