Effects of establishment method, seeding rate and soil fertility on the growth and persistence of a prairie grass pasture in the Waikato

Abstract

The production and persistence of 'Grasslands Mama prairie grass were compared when direct drilled or oversown at a low or high seeding rate, and with or without extra fertiliser before planting. To estimate possible effects of insects on prairie grass persistence, insecticide was applied to a small area. Prairie grass growth during the first winter/spring was greater when direct drilled than when oversown, but thereafter treatment effects disappeared. High seed rate plots maintained higher prairie grass plant and tiller densities than low seed rate plots during the first year, but this did not affect annual herbage accumulation, Two years from sowing, prairie grass plant and tiller densities had declined to a low level in all plots. At this time, prairie grass tiller density and prairie grass content (% of DM) in insecticidetreated areas were about twice those in untreated areas. Mean total annual herbage accumulation in the second year had declined by 21% compared with the first. This work shows that prairie grass does not require extra fertiliser at planting when sown into a well maintained high fertility site, and that direct drilling at a low seed rate produces results similar to those of the traditional method of establishment of oversowing at a high seed rate. Insect attack contributed to poor prairie grass persistence. Keywords Bromus willdenowii Kunth, oversowing, direct drilling, pasture botanical composition, major element composition, tiller density, insect damage, annual herbage accumulation, root yields