Identification of pasture mixtures that maximise dry matter yield

Abstract A mixture experiment was conducted to identify an optimal pasture seed mixture that maximised dry matter (DM) yield under irrigated, sheep-grazed conditions in mid-Canterbury, New Zealand. Nineteen seed mixtures were created using a simplex design from a pool of four species: perennial ryegrass, plantain, white clover and red clover. Seed mixtures were drilled into plots in March 2015 and the yield from sowing to May 2017 was modelled. The model analysis defined the optimal seed mixture proportions as 0.25 ryegrass, 0.28 plantain and 0.47 red clover of total number of seeds per unit area, or 7.5, 6.3 and 8.2 kg/ha, respectively (22.0 kg total seed). This mixture was predicted to yield 39.81 t DM/ha after 2 years. Ryegrass and plantain interacted more strongly with red clover than white clover, leading to increased yields over monocultures (diversity effects). Additional yield benefits arose from the three-species mixture of ryegrass, plantain and red clover. Keywords: diversity effect, pasture establishment, perennial ryegrass, plantain, red clover, seed mixtures, simplex design, white clover