SOIL PREPARATION

CHAPTER 2

2.5.2 Carbonate hardpan Carbonate hardpans form in warm semi-arid areas from parent material that contains high Ca concentrations. Calcium carbonate forms a massive cemented layer (Figure 2.7), which is impenetrable to roots and has slow water permeability. According to the South African Soil Classification system, soil forms that have hardpan carbonate horizons in the subsoil are Immerpan, Prieska, Plooysburg, Coega, Askham and Gamoep.

FIGURE 2.7: Carbonate hardpan in the subsoil (Coega soil form), massive and impenetrable to grapevine roots (Photo: ARC Infruitec-Nietvoorbij).

SOIL PREPARATION | 27