The utilisation of land for crop production is often accompanied by the modification of soil properties that may result in changes to other soil factors which may restrict crop growth. Some of the common soil factors likely to restrict crop growth include organic matter decline, soil structural limitations, pH limitations and the potential development of sodic soil or salinisation. Understanding and managing the optimal function of soil for crop production, in part, requires the assessment of basic soil properties that drive these soil factors. Routine analysis of soil supplies some of the information concerning these basic soil properties, while the more difficult and/or expensive to measure soil properties can be estimated from measured data using appropriate pedotransfer functions. It is not possible to identify a single soil property that may be used as an indicator that can monitor changes in these soil factors; rather it is the interrelationship and dynamics between several basic soil properties that drives changes in these soil factors. The objective of this study is to identify which soil properties and their interrelationships influence two soil factors that may influence crop production. Basic soil properties are estimated for the topsoil of 20 Vertosols utlised for cotton production in northern NSW. Statistical techniques such as classification and regression trees are employed to identify what interrelationships between the measured soil properties affect surface soil aggregate stability and soil available water capacity. It is demonstrated that several differing interrelationships between basic soil properties can result in similar stability classes. It is postulated that the identification of the interrelationships between basic soil properties is the first step to identifying a minimum data set of soil properties that form a rule base for estimating changes in soil factors affecting crop production.