WINETECH Technical Yearbook 2019

will be increasingly in demand for wine grapes. The next step is a thorough soil and terrain survey in suitable areas to measure the natural resources. This information is essential when taking decisions about cultivars and rootstocks and where these grapevines should be planted. Grapevines should be planted on high potential soils which promote bigger and deeper root systems. The grapevine with the stronger root system is the one which will handle the extreme climate better.

Following selection of the best soils, situated against the best slopes, soil samples are taken to adjust the soil fertility. Deep soil preparation is recommended to correct any physical and chemical limitations. Deep soil preparation is essential to ensure a deep, properly buffered root system which is able to resist the detrimental effects of climate change. Poor decision making, such as ridging and the incorrect method of making plant holes,

was highlighted. I warned against excessive irrigation and fertilisation, both of which create a lazy root system. The first irrigation should be postponed for as long as possible to force the roots to grow deeper in search of water and nutrients. In difficult times a shallow root system will not have the ability to supply the plant with water and the grapevine may be permanently damaged or even die. Dry land grapevines with deep root systems on good soils fared best during the drought,

while intensively irrigated grapevines on sandy soils struggled most when the taps ran dry. Subsequently I focussed on cover crops and the benefits thereof to the soil’s carbon levels. Cover crops reflect sunlight and keep the soil cool, increase infiltration and suppress the growth of weeds. Soils with a higher carbon content require less fertilisation and irrigation and make a difference to the water retention ability of sandy soils.

– For more information, contact Heinrich Schloms at heinrich@vinpro.co.za.