Oversowing of five grass species and white clover on a Taupo hill country pumice soil

摘要

Methods of establishing perennial ryegrass (Lolium perenneL.), prairie grass(Bromus willdenowiiKunth), phalaris (Phalaris aquaticaL.), cocksfoot (Dactylis glomerataL.), tall fescue (Festuca arundinaceaSchreb.), and white clover (Trifolium repensL.) by oversowing on a hill country pumice soil near Taupo were investigated in spring 1982 and 1983. Four pre-sowing sward treatments (paraquat herbicide application, hard grazing by sheep, treading by sheep, or treading by cattle) were applied in two experiments. Populations of seedlings, tillers, and plants, and herbage growth, were monitored for 2 years after each sowing. Degree of sward suppression resulting from sward treatments was the main factor influencing establishment success. Hard grazing resulted in minimal suppression of resident sward growth and hence poor establishment (2 of sown grass seed). Sheep treading yielded an average establishment rate of 4 of sown seed. Cattle treading removed most of the resident vegetation and resulted in high seedling emergence rates, but seedling survival was poor and final establishment was low (3 of sown seed). Paraquat herbicide application gave the best grass establishment (13) through a combination of high seedling emergence and good seedling survival. Large increases in the content of oversown grasses in swards occurred with time so that, in several instances, apparent establishment failures were rated as successful oversowings 2 years later. Grass species showed different responses to sward treatments and different rates of early growth, factors which should be considered when establishing grasses in this environment. Emergence of white clover cultivars Grasslands Tahora and Grasslands Huia averaged 60 of sown seed, but, with time, levels of white clover did not differ between sown and unsown plots.