SOIL PREPARATION

CHAPTER 7

without bringing the subsoil to the surface. It is also ideal to mix ameliorants with both top- and subsoil. Soils generally deep-ploughed using the mix-delve plough include Glenrosa, Swartland, Cartref, Valsrivier, Sterkspruit and Estcourt.

FIGURE 7.6: Shift-delve plough for mixing and sideways displacement of soil (Photo: ARC Infruitec-Nietvoorbij); dotted lines in sketch (right) show flow path of loosened soil (Sketch: J.E. Hoffman, Stellenbosch University). The mix-delve plough (also called finger plough) mixes soil in a special way. It causes minimum upward displacement of the subsoil (ARC Infruitec-Nietvoorbij, 2002). Soil moves slightly upwards but then tumbles back through the openings between the “fingers” while the soil that heaps up in front of the plough tumbles over the topmost blade.

FIGURE 7.7: Finger-delve plough that causes minimum upward displacement of the subsoil (left) (Photo: ARC Infruitec-Nietvoorbij) and sketch (right) with dotted lines indicating the flow path of loosened soil (Sketch: J.E. Hoffman, Stellenbosch University).

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