Soil Management in the Breede River Valley Wine Grape Region, South Africa. 2. Soil Temperature

Five soil management practices (treatments) were applied in a micro-sprinkler irrigated Chardonnay/99 Richtervineyard on a sandy clay loam soil near Robertson, commencing in April 1993 (one year after planting). The effectof the treatments on the soil temperature at a depth of 200 mm was measured on an hourly basis from April 1995 toMarch 1999. Differences in soil temperature between the un-mulched and mulched treatments, as measured in thegrapevine rows, were negligible from late April to the end of August. From mid-September (grapevine bud break)to the end of March, the temperature of the mulched soil was, with the exception of the third week in October, lowerthan that of the un-mulched soil. Results indicated that soil temperatures during early spring had a slight effect onthe onset of grapevine bud break. Mulching minimised the diurnal variation in soil temperature. The annual covercrop did not cause any delay in bud break and kept the soil temperatures below 25°C, with the exception of a threeweek period just before harvest.