Direct drilling tall fescue (Festuca arundinacea Schreb.) prairie grass (Bromus catharticus Vahl) and Italian ryegrass (Lolium multiflorum Lam.) into kikuyu and paspalum pastures

Abstract

Italian ryegrass (Lolium multiflorum Lam.), prairie grass (Bromus catharticus Vahl) and tall fescue (Festuca arundinacea Schreb.) were direct-drilled into paspalum and kikuyu pastures at Camden (1980-83) and Bega (1 982) in New South Wales. Prior to sowing, pastures were either slashed or slashed and sprayed with herbicide. In 1980, paraquat (0.28 kg a.i./ha) and glyphosate (0.5 kg a.i./ha) were compared with slashing-only at a March sowing. In 1982 and 1983, glyphosate only was compared with slashing, and grasses were sown on four occasions at 5-week intervals from late January or mid- February to early June. Seedlings were counted and weights of individual seedlings were measured at about 5 weeks after sowing, and pasture yield and species composition were measured 10 weeks after sowing, at the end of winter, and on selected plots, in winter in the following year. In 1980, plant density and dry matter yield at the first harvest of prairie grass and tall fescue was better from plots treated with glyphosate than from those treated with paraquat or slashed-only. However, plant density and dry matter yield of ryegrass was unaffected by preparation. In 1982 and 1983, plant densities 5 weeks after sowing increased with the use of glyphosate, and with later sowing. Prairie grass was least sensitive to sowing time establishing similar populations of between 50 and 150 seedlings/m2 from February to May. Tall fescue only established satisfactory seedling populations (50 to 200 seedlings/m2) at April and May-June sowings with glyphosate; it required suppression of competition, and low temperatures for faster growth than kikuyu and paspalum. The use of glyphosate reduced total pasture production during the first 10 weeks from 5 to 3 t/ha, but the contribution of sown grasses was increased. Winter production was greatest from sowings in March and April. Italian ryegrass always produced significant quantities of dry matter at the first cut and in winter; tall fescue was never productive in the first year. Persistence of prairie grass and tall fescue from 1982 sowings until 1983 was good, and highest tiller densities of 300-400 and 800 tillers/m2 respectively occurred from April sowings with glyphosate. Between June and September 1983, prairie grass and tall fescue from these plots produced about 3 and 2 t/ha of dry matter respectively. As seedling vigour declined from Italian ryegrass to prairie grass to tall fescue, conditions required for successful establishment became more stringent. Persistence and production of perennials was excellent if sown at the right time to encounter favourable temperatures, and competition was suppressed. Mixtures thus established need to be assessed on a paddock scale under grazing to determine their final viability.