COVER CROPS in South African Vineyards

CHAPTER 8 EFFECT OF COVER CROPS ON GRAPEVINE NUTRITION AND PERFORMANCE

Reference list Conradie WJ. 1994. Vineyard Fertilisation. Proceedings of a workshop on fertilization, Nietvoorbij, 30 September,ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599. Conradie WJ. 2001. Timing of nitrogen fertilization and the effect of poultry manure on the performance of grapevines on a sandy soil. II. Leaf analysis, juice analysis and wine quality. South African Journal of Enology and Viticulture , 22(2), 60–68. Fourie JC, Louw PJE andAgenbag GA. 2006. Cover crop management in a Chardonnay/99 Richter vineyard in the Coastal region, SouthAfrica. 2. Effect of different cover crops and cover crop management practices on grapevine performance. South African Journal of Enology and Viticulture , 27(2), 178–186. Van Huyssteen L and Weber HW. 1980. The effect of minimum and conventional tillage practices in vineyard cultivation on vine performance. South African Journal of Enology and Viticulture , 1(2), 77–83. Lower Orange River region The study was conducted on cover crops in a table-grape vineyard under full-surface micro-sprinkler irrigation near Keimoes. Nitrogen status of vines The nitrogen levels in the grapevines in the different cover-crop treatments and the control are shown in Figure 8.18. Measurements of nitrogen as nitrates in the leaf petioles of grapevines were done at flowering. Grazing vetch increased the nitrogen levels significantly, as did oats when sown annually. Nitrogen levels in these treatments was above the threshold of 1 000 milligram per kilogram where nitrogen fertilisation at grapevine berry set is not necessary.This suggests that cover crops can reduce the need for inorganic nitrogen application during the grapevine-growing season on these sandy soils. However, the vines experienced a shortage of nitrogen when oats were sown every two years. Nitrogen levels were also low where no cover crop was grown, and where perennial dwarf fescue was established.This demonstrated that these management practices require an increase in nitrogen fertilisation during the grapevine-growing season to avoid deficits.

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