Sampling considerations for surveying copper concentrations in Australian vineyard soils

Abstract

The Australian wine industry has funded a study to determine the concentrations of copper in vineyard soils and to assess whether the continued use of copper-based fungicides is likely to be detrimental to the long-term agricultural sustainability of vineyard soils. Prior to the conduct of regional surveys to determine copper concentrations in vineyard soils, a preliminary study was conducted in 6 vineyards near Mildura (34°S, 142°E) (north-western Vic., Australia) to determine sampling considerations. The study investigated the distribution of copper in the soils of vineyards with 3 different histories of copper-based fungicide use: <5 years old; at least 30 years old during which time the vineyard had been ploughed and replanted; and at least 60 years old. At 3 locations in each vineyard, soil samples were collected from 2 depths (0–0.15 and 0.15–0.30 m) at 0.30-m intervals along two 1.50-m-long transects running at right angles in opposite directions from the vine trunk towards the inter-row areas. The results showed that copper concentrations were higher in the top 0.15 m of soil (P < 0.001) and declined with distance from the vine (P = 0.002). The variation in copper concentrations between vineyards was found to be much greater than the variation within vineyards (variance component of 0.7746 and 0.0893, respectively). Balancing an acceptable level of error with the resources required to collect samples, we recommend obtaining 1 composite soil sample from each vineyard in regional surveys to determine copper concentrations in vineyard soils. Sampling depth and distance from the vine should also be taken into consideration in future soil sampling depending on the objective of the study.