Removal of pruned vine biomass (PVB) from vineyards – Examining the impact of not incorporating PVB into vineyard soils

The wine industry worldwide faces increasing challenges to achieve sustainable levels of carbon emission mitigation. This study seeks to establish the feasibility of harvesting winter pruned vineyard biomass (PVB) for potential use in carbon footprint reduction as a renewable biofuel for energy production. Of particular interest is the role PVB plays as a carbon source in vineyard soils and what effect annual removal might have on soil carbon. An investigation was carried out in the Coombe vineyard, Waite Campus (University of Adelaide), Australia. Vines are grown in a Vertic clay loam soil with well-managed mid-row swards in a temperate zone. A comparison was undertaken of two mid-row treatments after 13 years of consistent management: 1) the deliberate exclusion of PVB from every third row, and 2) in the remaining rows PVB was incorporated at an average of 3.4 and 5.5 t/ha in two 0.25 ha blocks containing Shiraz and Semillon respectively. In both 0-10 cm and 10-30 cm soil core sample depths, combined soil carbon % values in the desired range of 1.80 to 3.50 were not significantly different between treatments or cultivars and yielded an estimated 42 t/ha of soil carbon. Other key physical and chemical values were likewise not significantly different between treatments. Results suggest that in a temperate zone vineyard, managed such as the one used in this study, there is no long-term negative impact on soil carbon sequestration through removing PVB. This implies that growers could confidently harvest PVB for use in biofuel production.