Feasibility of winter cover crop production under rainfed conditions in the eastern Cape Province of South Africa.
Low winter rainfall poses a challenge to production of high biomass from cover crops, which is necessary for the success of conservation agriculture systems in the Eastern Cape Province of South Africa. An experiment was conducted to evaluate the adaptability of white oats (Avena sativa), grazing vetch (Vicia dasycarpa), rye grass (Lolium multiflorum), barley (Hordeum vulgare), radish (Raphanus sativa) and triticale (Triticale secale) production under low winter rainfall conditions in the Eastern Cape. The cover crop species were relayed into maturing maize (Zea mays L.) in February, March and April of 2010, exposing them to varying rainfall conditions. They were followed with summer maize. Growth rate and final biomass of cover crop species decreased with delayed planting, except for radish. February planted cover crops had the lowest residues remaining at maize planting, resulting in higher weed dry weights at 3 and 6 weeks after planting (WAP). April planted cover crops improved soil N by a greater margin compared to earlier plantings, which were comparable within their category. Grazing vetch and radish resulted in the greatest soil N improvement. Significantly higher (P<0.05) maize grain yield was recorded in grazing vetch, while all other species had comparable yields. It is, thus feasible to produce cover crops under winter rainfall conditions in the Eastern Cape and grazing vetch and radish can serve this purpose.
Key Words: Barley, oats, radish, vetch