EFFECT OF COMPOSTED MULCH APPLICATION ON SOIL AND BUNCHZONE TEMPERATURE IN 'SEMILLON' GRAPEVINE

This paper reports on the effect of recycled organic composted mulch application on soil and bunch zone temperature differences when compared to grapevines grown on bare under-vine soil across three different sites in the Hunter Valley (2009-2010). Soil temperature was measured using MEA GTBUG data loggers at 10 cm depth. Soil temperature under the composted mulch treatments were consistently buffered on two irrigated sites across the entire vintage period. However, limited differences were observed in soil temperature at the one dry-land site. Bunch zone temperature positioned at ±10 cm on the cordon wire were measured using Dallas Semiconductor 1 Wire I-Buttons, housed within semi-enclosed ventilated PVC pipe. Daily average bunch zone temperatures were consistently lower in mulch treatments at the maximum temperature across all three sites. Limited differences resulted between treatments at the minimum temperature on a daily basis across all sites. All mulch treated vines across all sites spent less ‘hang time’ above 35°C and more time within an ‘optimum’ of 15-35°C than bare under-vine soil grown vines from veraison to harvest. The data reported from this trial provides a clear benefit of using composted mulch on either irrigated or dry land sites of different soil types as a management tool to enhance the viability of ‘Semillon’ within the Hunter Valley under increased temperature. Further replicated studies are continuing across the three established ‘Semillon’ sites and three new ‘Shiraz’ sites over the 2010-2011 vintage.