SOIL PREPARATION

In the winter rainfall area soil preparation is normally done after the soil has adequately dried after winter. Establishing a cover crop on the land will aid the drying while clean cultivation after winter will conserve moisture which will allow soil preparation at ideal soil water content even in late summer and autumn. 7.1.2 Single versus double tillage In most cases soil preparation using a ripper or a wing plough needs to be done in two directions, i.e. in a grid pattern, in order to create a uniformly loose medium that can be fully exploited by roots. Single-direction delve ploughing tends to yield a sandwich effect (Figure 7.17) that impedes soil water drainage and also water and root distribution. A second tilling at an angle of 60° to the first work direction will give good mixing of the soil.

FIGURE 7.17: Sandwich pattern of soil layering obtained with single-direction delve- ploughing of a sandy soil (Photo: J.E. Hoffman, Stellenbosch University).

Double tilling is not a general recommendation. Inspection of profile pits, after single-direction tilling has been done, will be necessary to decide on the need for double delving. The decision whether double tilling will be necessary depends on factors such as soil texture, gravel content, shape of the mouldboard, and soil water content. Single-direction tillage should be adequate in most cases if the correct choices were made regarding implement type, cutting width and soil conditions.

124 | CHOICE OF IMPLEMENT FOR SOIL PREPARATION