Soil pH changes in drip irrigated vineyards
Abstract
Grapevines, like most plants, are affected by soil pH. In acidic soils, root growth is restricted resulting in a reduced ability of the vine to explore the soil volume for water and nutrients whilst in alkaline soils vines can suffer from zinc, iron, manganese and copper deficiencies. Building on previous work conducted for Land and Water Australia, this project aimed to investigate the occurrence of extreme soil pH in Australian viticultural soils and to develop and refine a
calculator of soil pH change and deliver it to growers. Key outputs from the project included assessment of soil pH change in 6 major Australian viticultural regions (Hunter Valley – New South Wales, Central Ranges/Southern Highlands – New South Wales, Murrumbidgee Irrigation Area (MIA) – New South Wales, Eastern Victoria, Western Victoria and Margaret River - Western Australia); further development of a “Calculator of soil pH change” following analysis of ash alkalinity of wine grapes and assessment of the effect of water quality on soil pH; and presentation of the refined Calculator to grower groups in each viticultural region.
Summary
Grapevines, like most plants, are affected by soil pH. In acidic soils, root growth is restricted resulting in a reduced ability of the vine to explore the soil volume for water and nutrients whilst in alkaline soils vines can suffer from zinc, iron, anganese and copper deficiencies. Previous work has shown that long term use of ammonium or urea based nitrogen fertiliser results in acidification whilst in some other districts, soil pH has tended toward alkalisation, presumedly due to the composition of irrigation water.
The Australians and Natural Resource Management 2002 report published by the National Land and Water Resources Audit (NLWRA) estimated annual losses caused by soil acidification in viticultural regions in Australia in 2000 to be as high as $118M. These losses were considered to be too high by the industry and would, in many cases, be the difference between making a profit and a loss. In response to these claims, Scholefield Robinson Horticultural Services (Scholefield Robinson) completed a project for Land and Water Australia (LWA) in 2003-2004 entitled “Vineyard Acidification Audit” in which the pH and buffering capacity of Australian viticultural soils was assessed and a Calculator of Soil pH Change developed to allow assessment of the risk of soil pH change in drip irrigated vineyards. However, this LWA funded project highlighted the need for more work to refine the Calculator of Soil pH Change and to assess soil pH in other viticultural regions of Australia considering that only vineyards in South Australia were investigated. This GWRDC-funded project aimed to address these requirements by investigating the occurrence of extreme soil pH in Australian viticultural soils and by further development and refinement of the Calculator of Soil pH Change, which was then presented to growers.