Soil quality, in a viticultural context, can be thought of as the soil’s ability to support grapevine growth and the production of a crop (with consideration to both yield and quality) without resulting in soil degradation or harm to the environment. It includes the functions of soil such as the provision of a medium for vine growth, the retention and release of water, nutrient cycling and the regulation of biological populations. The assessment of soil quality should therefore include the analysis of its physical, chemical and biological properties. By conducting a range of field and laboratory analytical tests, grape growers can determine
whether corrective action is required to alleviate any constraints to soil use or whether their practices are having any beneficial or deleterious impacts on soil quality. In established vineyards, soil testing is undertaken regularly (i.e. annually or biennially) in order to provide information that is required for making decisions on the need for and application rate of inputs such as fertilisers, soil amendments (e.g. lime and gypsum) and bio-fertilisers/inoculants (i.e. products which contain living micro-organisms).
Regular soil monitoring over time using sound sampling and measurement strategies is important. There is no single descriptor of soil quality; instead a ‘tool kit’ of indicator tests is used. Results from these tests should be evaluated by comparing them with known benchmark (or optimum threshold) values and vine performance criteria such as crop yield and fruit quality. Benchmark values should be evaluated against vine performance on a regional basis using different soils and management practices over time.
The field and laboratory measurements described in this publication have been selected on the basis of scientific
merit and practicality (e.g. Oliver et al. 2013, Riches et al. 2013). For some soil tests (e.g. biological properties), little information is available on benchmark values to aid data interpretation.