COVER CROPS in South African Vineyards

COVER CROPS IN SOUTH AFRICAN VINEYARDS

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Irrigation water supplied in millimetres

0 Sown annually Sown two- Sown annually Sown two- Sown five- yearly Dwarf fescue yearly yearly Grazing vetch Triticale

Chemical

Mechanical control

control

No cover crop

FIGURE 6.2. The amount of irrigation water per hectare per annum required in vineyards with and without cover crops under full-surface micro-sprinkler irrigation in the Breede River valley. Adapted from Fourie (2015). the requirement when no cover crop is present. In contrast, the requirement in the grazing-vetch treatment was greater than the control, due to the additional water needed for the vetch to complete its life cycle. The water consumption of a vineyard with a perennial dwarf-fescue cover crop was 731 millimetres per hectare per year.This was significantly higher than the water requirement of the annual cover-crop treatments, or of the control with no cover crop. The increased irrigation needed to maintain a perennial cover crop, especially in drier regions, is one of the reasons why perennial cover crops are not recommended. These results illustrate that the summer mulch provided by annual cover crops can reduce the total irrigation requirement of a vineyard by as much as 86 millimetres per hectare per year in the Breede River valley. However, keep in mind that the growing cover crop may increase water use if not controlled during bud-break. Reference list Fourie JC. 2015. Soil tillage, cover crops and weed control as part of an integrated approach to the cultivation of grapevines. Part 3: Amount of irrigation water needed per hectare as affected by soil management. Wineland July, 76–79.

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