Review: soil biological properties as indicators of soil quality in Australian viticulture

Any reduction in soil quality as a consequence of production practices, through processes, such as erosion, salinisation, sodicity, acidity and structural decline, threatens the long‐term sustainability of winegrape production. Monitoring of soil quality is thus needed to identify when degradation is occurring in order to allow management intervention. This review examines the suite of biological indicators available for this purpose and the potential for their adoption as part of a minimum dataset by industry. Physical and chemical indicators are discussed in a companion paper. Many groups of organisms and various biological processes have been used as indicators of soil quality in research programs. There is a lack of consensus, however, on which are the key indicators for extensive monitoring programs, and little information is available on threshold values to aid data interpretation. At present, only soil organic carbon (together with labile carbon), potentially mineralisable nitrogen and microbial biomass can be recommended for measuring the biological aspects of soil quality in Australian viticulture. Although newer molecular methods have been developed to elucidate the community structure and genetic profiles of groups in the soil biota, and thus supplement measurements of microbial biomass, these methods are not readily available through commercial laboratories. Moreover, with the exception of tests for some pathogenic organisms, these measurements have not yet been linked to soil functions influencing grapevine growth and nutrition and so are not suitable for routine monitoring of vineyard soil quality.