COVER CROPS in South African Vineyards

CHAPTER 4 COVER-CROP ESTABLISHMENT

The results obtained with the six treatments are illustrated in Figure 4.8. Seed germination in grazing vetch and Paraggio bur medic was improved when using a rotary harrow (treatments 5 and 6) compared to the disc harrow (treatments 1 and 2), or a combination of disc harrow and a cultivator (treatments 3 and four).A cultivator (ghrop) should not be used to cover the seeds of plants with medium-sized, elongated seeds like rye, as it reduces seed germination. Although the incorporation of plant residues into the soil prior to sowing did not improve the germination of Paraggio bur medic, it improved the dry- matter production. Incorporation of plant residues also tended to improve the dry-matter production of rye. In addition to the implements discussed above, a planter can also be used to establish cover crops (Figure 4.9). The advantage of a planter is that soil cultivation, to break the surface crust just before the seeds are sown, is unnecessary.A planter ensures that the seeds are placed at the correct depth. The seeds are also more evenly spread over the surface area than when sown by hand.

FIGURE 4.9. Two types of planter. On the left, a commercially available model from Piket Implements, and on the right, a planter made by a farmer for his own use. (Photo: ARC Infruitec-Nietvoorbij). As seen with other implements, the cover-crop stand is improved when the planter is used in combination with the incorporation of plant residues from the previous season into the soil four to six weeks before sowing. Reference list Fourie JC and Ochse CH. 2002. Die invloed van verskillende vestigingsteg- nieke op dekgewasprestasie. Wynland Mei, 11–12.

90