SOIL PREPARATION

CHAPTER 5

Under dryland conditions new vineyards on ridges should be established under a plastic ground cover. Ridged vineyards should have preference when the allocation of irrigation water is considered, but only micro-sprinkler or drip systems should be used. Conventional sprinkler systems will cause too much run-off as well as erosion of the ridges. The use of herbicides for weed control will be essential on ridges, while mulching is beneficial to lower soil temperature and prevents excessive drying of the topsoil. It also promotes exploitation of the full root volume, even close to the surface. Ridging is considered to be a soil preparation method, but it has occasionally been used by growers in old existing vineyards to induce a yield increase and keep the vineyard economically viable for a year or two longer. Root studies showed that in such vineyards, the graft unions are covered by soil, causing scion roots to form. Due to the danger of phylloxera infestation in the roots of the scion, ridging of existing vineyards is not a recommended practice.

FIGURE 5.6: Vineyard successfully grown on ridges at an in-row spacing of 1.5 m and inter- row distances of 2.0 m on top of ridges and 3.7 m between ridges which is equivalent to a plant density of 2 339 grapevines per ha (Photo: J.L. van Zyl, Stellenbosch University).

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