COVER CROPS in South African Vineyards

CHAPTER 6 EFFECT OF COVER CROPS ON WATER USE

break, the average water requirement was approximately 190 millimetres per hectare per year.This reduction is due to the water-saving summer mulch created by the cover crops. When chemical control of the cover crops was left until grapevine berry set, the average water requirement was approximately 238 millimetres per hectare per year, which is similar to the requirement when no cover crop is present.This is due to the additional water needed for the cover crops to grow and set seed. However, even with later chemical control, the rye treatment still used about 10 millimetres less water than the control with no cover crop, probably due to its short lifespan. These results illustrate that the summer mulch provided by cover crops can reduce the total irrigation requirement of a vineyard in the Coastal region by as much as 50 millimetres per hectare per year. 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. Breede River valley A trial in the Breede River valley was conducted over ten seasons at the ARC Infruitec-Nietvoorbij research farm near Robertson in the Western Cape. The site had sandy clay loam soils.Annual cover crops were sown in autumn. Rainfall was supplemented with irrigation as needed. The vineyard required an average of 592 millimetres of water per hectare per year when no cover crop was present.When triticale or grazing vetch was sown annually, and chemical control started just before bud-break, the average water requirement was approximately 534 millimetres per hectare per year.This reduction is due to the water-saving summer mulch created by the cover crops. When chemical control of the cover crops was left until grapevine berry set, the average water requirement in the triticale treatment was similar to

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