Nitrogen and grassland production in the mid‐altitude zone of Canterbury, New Zealand

An account is given of three experiments conducted on uncultivated grasslands in the fescue tussock zone of the Broken River Basin. Where other nutrients were not limiting, constant returns in grass yield were shown to increments of nitrogen up to 200 lb N per acre. On both poor and good sites grass yield was increased fivefold with applications of nitrogen at the level of 200 lb N per acre. Increases were shown to persist for at least two years after fertiliser application on the poor sites. In the presence of adequate supply of other nutrients the adventive grasses, especially Yorkshire fog, tended to be superior to native grasses in response to nitrogen applications. Where sulphur and phosphate were in scarce supply, browntop responded more to fertiliser nitrogen than did sweet vernal. In discussion of results some changes are predicted in pasture production and composition as the outcome of different manuring and grazing management policies.