COVER CROPS in South African Vineyards

CHAPTER 3 COVER-CROP SELECTION

Total dry-matter production of the vetch was approximately 8.0 tonnes per hectare, which was sufficient to control weeds. Dry matter did not increase significantly from the end of August to early November, suggesting that there is no benefit in allowing the cover crop to grow after grapevine bud-break. Interestingly, dry-matter production of the vetch in this trial was 3.53– 6.52 tonnes per hectare more than that recorded in the Coastal region. Reference list Van Huyssteen L, Van Zyl JL and Koen AP. 1984. The effect of cover crop management on soil conditions and weed control in a Colombar vineyard in Oudtshoorn. South African Journal of Enology and Viticulture , 5(1), 7–17. Lower Orange River region

COVER CROPS REQUIRE FULL- SURFACE SPRINKLER OR MICRO-SPRINKLER IRRIGATION IN THE SEMI-ARID LOWER ORANGE RIVER REGION, AS WINTER RAINFALL CANNOT SUPPLY THEIR NEEDS.

Trials in this region were conducted on the farm Boomplaas near Keimoes, in the Northern Cape. Cover crops require full-surface sprinkler or micro-sprinkler irrigation in this semi-arid region, as winter rainfall cannot supply their needs. Vineyard trials Cover crops were chosen for evaluation in this region based on the results of open-land trials in the Breede River valley and Olifants River

valley. Four grasses (dwarf fescue, rye, Overberg oats, and black oats) and four legumes (grazing vetch,Woogenellup subterranean clover, Paraggio bur medic, and pink serradella) were assessed over four seasons. Annual cover crops were sown each year in March in the work row. Full- surface chemical weed control was applied from just before bud-break until harvest. Dwarf fescue, a perennial grass, was sown once, and was slashed during the grapevine-growing season. The cover crops received 8 millimetres irrigation twice weekly for the first four weeks after sowing, following by 16 millimetres irrigation per week for the following four weeks.Thereafter, they received 16 millimetres irrigation every two weeks until the start of the grapevine-growing season in August.

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