Winetech Technical Yearbook 2022

• Subsoils in which vertical eluviation of clay has occurred: the removal of soil material in suspension from a part of the entire soil profile. The s t ruc t ur e s i n the pedo - or prismacutanic B horizon (clay horizons) (photo 6) are not water stable and, therefore, must never be ploughed to the surface. If this happens, the clay peds disperse on the surface and form a crust which delays water infiltration with a subsequent decrease in the soil water content and increased erosion vulnerability. The restrictive layer can be broken up with a mix-rip implement if the clay horizon has sufficient structural stabi l i ty and won’ t return to the compacted state again after loosening. The action must occur during ideal soil water conditions to achieve the best uplifting action. SOIL PREPARATION The soil’s chemical and physical conditions will determine the planting date; certain soils must go through a rehabilitation process first. For example, if the lime recommendation exceeds 25 - 30 tons/ ha, or drainage has to be installed to, for instance, leach out excessive salts, any planned vineyard establishments would have to be postponed in favour of starting the rehabilitation process. After the nec essary actions have been carried out, the soil is re-evaluated after 6 - 12 months to determine if additional adjustments are re quired and whether the preparation action or drainage installation was successfully performed. The soil type determines the correct im plement choice, considering the chemical limitations. IMPLEMENT CHOICES FOR SOIL PREPARATION We have various names for the same im plements, namely ripper, rippers with wings (two or three toes) (photos 7 and 8), mix ripper (photo 9), finger delve (photo 10) and excavator (no longer recommend ed). An ideal implement for all purposes does not exist; the soil’s limitations will determine the specific implement to be considered. In certain blocks on the same farm, there will also have to be varying use between different implements, as soils in the Western Cape can vary enormously over a short distance. The following factors also have to be considered in the choice of implement: • Soil water content : A soil that is too wet, smears, and no crumbling occur in the subsoil. Soils that are too dry break up into large clods, and uneven distribution

PHOTO 7. Ripper with wing on toes.

PHOTO 8. Ripper with swing wings behind toes.

PHOTO 9. Mix rip (ripper with swing wing behind toe and scrapers that mix downward).

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WINETECH TECHNICAL YEARBOOK 2022