Hill country pastures, botanical composition and productive capacity


  • G.P. Cosgrove
  • T.R.O. Field


Botanical composition of pastures is indicative of their dry matter production and nutritive value and so capacity for animal production. Two previous national pasture surveys were conducted in 1935/1940 and in 1987/1988, and one regional survey in 1967/1968, to assess the state of this resource across all land classes. Among many purposes, results from these surveys were used to assess the outcomes of technological advances such as aerial topdressing and oversowing in hill country from the 1950s onwards, and to record changes in the abundance of particular species such as C4 grasses that could indicate effects of climate change, and identify research needs and opportunities. In the 28 years since the most recent survey, there have been many changes in the farm operating environment. This is particularly so in hill country, where other sectors such as forestry and dairy have encroached on traditional sheep and beef land, and poor profitability has forced variable and often sub-maintenance applications of phosphate (P) and sulphur (S) fertilisers. However, the low use of P and S has been partly offset by increased use of nitrogen (N) fertiliser. The declining number of beef cows, substituted by growing dairy and dairy-beef cattle, and the remarkable increase in the per head productivity of sheep are probably the biggest changes shifting the feed demand profile and the ratio of mature: young livestock. These changes affect pasture utilisation. This paper will consider the possible effects of those changes over the 28 years since the most recent national survey of pasture botanical composition, and the future capacity and resilience of this important resource to cope with continuing farm system change, emerging pressures for productivity growth, and regulatory and compliance requirements. Keywords: hill country pasture, botanical composition, resource status, survey






Past volumes