Hill country pastures in the southern North Island of New Zealand: an overview

Abstract

The 4 million ha of hill country pastures in New Zealand grow mostly on steep slopes and soils of naturally low soil fertility. Pastures are based on approximately 25 exotic species introduced within the last 130 years after the forest was cleared and burnt. Despite the environmental constraints and naturalised species, hill country is a major contributor to agricultural exports. The landscape and the pastures are spatially diverse, with slope and aspect strongly influencing the abundance and production of pasture species. The number of pasture species present is relatively stable, but the relative abundance of high fertility grass species (e.g. perennial ryegrass, Lolium perenne), low fertility grass species (e.g. browntop, Agrostis capillaris) and legumes (e.g. white clover, Trifolium repens) can be shifted towards high fertility grass species and legumes through the interaction of phosphate fertiliser application and grazing decisions (that is, sheep versus cattle, stocking rate, grazing management). Increased proportions of desirable species and improved soil fertility and structure can support sustainable farming systems. There are challenges such as soil erosion and nutrient loss into waterways, but these are more readily managed when the pastoral system is productive and profitable. Keywords: slope, pasture condition, browntop, perennial ryegrass, soil characteristics