VARIATION IN GRASSLAND PRODUCTION IN THE NORTH ISLAND WITH PARTICULAR REFERENCE TO TARANAKI

Abstract

Variation in levels of annual dry matter production is discussed for the North Island. On average most sites on flatland farms are capable of producing at least 9000 kg DM ha-r under fortnightly and 11000 kg DM ha-r under monthly cutting, These yields arc slightly lower than yields recorded on experimental farms. Variation in seasonal patterns of pasture production is compared between districts. The major geographical effect on pasture growth is related to climate and the water holding capacity of the soil. Within district variation is considered in detail for Taranaki (Waimate West and Stratford). Pasture growth in spring is strongly correlated with daily maximum air temperature (r2 = 0.73***) and accumulated heat units ( > 6°C) for lOcm soil temperature (r2 = 0.91 ***). Pasture growth rates were at least 25% higher in spring with a cutting interval of four weeks than with two weeks. The use of rate of growth data from standardized MAF trials for feed budgeting purposes is discussed.