COVER CROPS in South African Vineyards

COVER CROPS IN SOUTH AFRICAN VINEYARDS

Control the cover crop with the appropriate dosage of a post-emergence her- bicide four weeks before planting the grapevines. Flatten the cover crops before planting starts. Do this manually, not with tractors and tractor-drawn implements. It is important to prevent traffic on the soil at this stage, as traffic will contribute to compaction. PREVENT TRAFFIC ON THE SOIL BEFORE PLANTING GRAPEVINES, AS TRAFFIC WILL

RECOMPACT THE LOOSENED SOIL.

The mulch created by the cover-crop residues will help to suppress weeds during the first year after planting the grapevines. Cover-crop management in established vineyards

Incorporate the mulch created by the cover crops in the previous year into the soil using a disc harrow. It is important to do this at least four weeks before the sowing date, because the addition of the mulch to the soil will increase microbial activity, leading to a short-term nitrogen deficit in the topsoil. If this deficit coincides with cover-crop sowing, the cover crop will not establish properly and will fail to produce enough dry matter. The mulch from the previous year should be incorporated four weeks before sowing even when a planter is used to sow the seeds. Incorporation of superphosphate during seedbed preparation will help to supply the nutritional needs of the cover crops, especially legumes and brassicas, but must remain within the limits of the fertilisation programme for the grapevines. If available, a planter is preferable for establishing cover crops, as the depth at which seeds are placed, as well as the seeding rate per surface area, are better controlled.When a planter is not used, soils that tend to form a surface crust should be tilled just before sowing, preferably using a rotary harrow. Seeds should be covered with a thin layer of soil (maximum 25 millimetres) directly after sowing by means of a shallow cultivation, preferably using a rotary harrow.This is especially important in the case of the small-seeded bur medics, snail medics, canola, Caliente 199, white mustard, and Nemat. Make sure that a roller is mounted behind the rotary harrow to improve contact between the seeds and the soil.

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