Some insights into the health of Dermosols around Tasmania, Australia

Abstract

Previous research in Tasmania has provided information on the effects of land management on soil properties. However, there remains a lack of data on if and how soil health in Tasmania is changing over time. The Soil Condition Evaluation and Monitoring (SCEAM) project was developed to provide reliable data on soil condition and to fill this gap by providing information on soil health on a 5-yearly basis. The SCEAM project measures several soil properties considered to be indicators of soil condition, for a variety of soil–land use combinations from around the state and will enable the identification of trends in soil condition over time. Dermosols are the dominant soil type in Tasmania and 59 sites comprising this soil order were assessed for a range of key indicators of soil condition, including pH (1 : 5 soil : water), organic carbon, bulk density and aggregate stability. Target values for each soil property were identified based on local expert knowledge and are intended as a trigger for further site investigation rather than to label soils healthy or otherwise. Baseline data were collected for each site which was subsequently resampled 5 years later to provide a repeat set of results for comparison. The data showed that most sites have declined in condition based on the results for one or more indicators. So far, the changes identified between sampling rounds are generally small and the number of sites with indicator values that fall outside identified target values is low. However, for some indicators the number of sites outside identified target values has increased between the two sampling rounds. The greatest degradation impacts are observed for Dermosols under cropping. The results provide an early warning that although improved crop varieties and fertiliser applications may, in the short-term, be able to overcome yield declines as a result of soil degradation, long-term agricultural activities are continuing to have an adverse effect on soil health.