COVER CROPS in South African Vineyards

CHAPTER 7 EFFECT OF COVER CROPS ON SOIL CARBON AND MINERALS

Figure 7.5 shows the potassium levels for the 0–600-millimetre soil levels measured after harvest in 2003. The levels are particularly high in the treatment with perennial dwarf fescue, which suggests that planting this cover crop on these soils could exacerbate the accumulation of potassium. st mber otation ion August November

No cover crop

Perennial dwarf fescue Grazing vetch weed control November Grazing vetch weed

control August Triticale|vetch annual rotation Triticale|vetch

two-yearly rotation Rye|faba bean mix

Triticale weed control November Triticale weed control August 0

300

500

100

200

600

400

Potassium in milligram per kilogram soil FIGURE 7.5. Soil potassium measured after harvest in the 0–600-millimetre soil layer in cover-crop treatments compared to a control in the Breede River valley. Adapted from Fourie (2012). Reference list Fourie JC. 2012. Soil management in the Breede River valley wine grape region, South Africa. 4. Organic matter and macro-nutrient content of a medium-textured soil. South African Journal of Enology and Viticulture ,

33(1),105–114. Coastal region

Unless otherwise mentioned, the trials in the Coastal region were conducted at the ARC Infruitec-Nietvoorbij research farm near Stellenbosch in the Western Cape. Eight cover crops, namely Henog rye, Overberg oats, Saia black oats, grazing vetch, faba bean, Paraggio bur medic, Kelson snail medic andWoogenellup subterranean clover, were compared to a control without a cover crop.

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