Responses of ryegrass, browntop, and an unimproved resident pasture in hill country, to nitrogen, phosphorus, and potassium fertilisers: 1. pasture production

Abstract

The response characteristics of a 'Grasslands Ruanui' rye grass (Lolium perenne L.) sward, a browntop (Agrostis tenuis Sibth.) sward, and a resident unimproved pasture to N, P, and K fertilisers were determined using a mowing study based on a 3-factor response surface design. Swards were established on low fertility hill country (slope 5°-10°) in the southern Ruahine Range. Fertilisers were applied at rates up to 80 kgP/haJa, 896 kgN/ha/a, and 430 kgK/ha/a over 3 years. Swards showed large responses to Nand P but little response to K. Significant N x P interactions occurred on ryegrass, but not on other sward types. Annual and seasonal pasture production differed with sward types, with resident and rye grass swards out-yielding browntop swards under most fertiliser combinations. Fertiliser application increased the proportion of annual pasture growth occurring over winter and reduced the proportion that occurred over the summer and autumn in all pastures. © 1981 Taylor & Francis Group, LLC.