Run for cover–the ‘right’ species of under-vine cover crops do not influence yield in an Australian vineyard

Reducing herbicide application in viticulture is of increasing importance due to tightening regulations in multiple export markets, and consumer demands. As a result, alternative vineyard floor management options are becoming increasingly sought after in the context of sustainable viticulture. This trial aimed to quantify the effects of different under-vine ground cover species on soil properties and vine productivity and to reassess whether bare soil under-vine compares with a covered under-vine zone. In 2014, six under-vine treatments, including straw mulch, herbicide, medic (Medicago L.) mixes, and grasses (Wallaby grass [Rytidosperma sp. L], fescue [Festuca sp. L], and Cocksfoot [Dactylis sp. L]) were established in an irrigated vineyard field trial at Langhorne Creek, South Australia. In 2020, data on soil physical and chemical properties, moisture content, and leaf nutrient status were collected from the site. Yield data from 2016–2021 were also collected. Cover crop species seeded in the under-vine space play a major role in defining vine productivity but do not necessarily have a negative impact. Analysed using a linear mixed model, yields over six seasons were no different between the herbicide control, straw mulch, and the medic treatments. That is, there was no yield penalty with specific cover crop treatments. However, significant negative effects on yield were observed relative to the herbicide control, with more aggressively growing perennial grass treatments. In Australia, seed blends including Medicago species provide viticulturists with new tools to enhance their vineyard’s soil health and hence sustainability of their operations.