WILD WHITE CLOVER SEED PRODUCTION

Field experiments on the management of ryegrass/white-clover pastures for seed production were carried out from 1958 to 1961. Replicated trials with ¹/₆-acre plots compared continuous grazing, rotational grazing and cutting once at the silage stage of growth as methods of pasture management from April to June. An additional mechanical method, gang mowing, was introduced in 1960 and Hayter mowing was used in 1961. In 1958 to 1960 the treatments were studied with and without the application of 70 lb nitrogen per acre. Clover flower heads per square foot, clover seed and ryegrass seed yields were greatest under continuous grazing, although in some years comparable results were obtained from the mechanical defoliation treatments. There were substantial differences between potential and harvested clover seed yields, the latter ranging from 20% to 75% of the potential yield. The weight of ryegrass seed harvested was highest under continuous grazing and least under the cutting treatments. The nitrogenous fertilizer increased the production of herbage dry matter and of ryegrass seed, but greatly reduced clover seed yields. The results are discussed in relation to the influence of weather on the incidence of flowering and the influence of methods of defoliation on flower-bud emergence. It is concluded that mechanical methods of defoliation can produce yields similar to those obtained under continuous grazing, provided that cutting is carried out at the correct stage of growth.