INFLUENCE OF PHYSICAL FACTORS ON PASTURE GROWTH ON HILL COUNTRY

Abstract

Pasture on north aspects of steep hill country (Waingaro steepland soil) produced more dry matter than on south aspects (7100 kg/ha cf. 6400 kg/ha) owing predominantly to a significantly higher growth rate during winter and early spring. Pasture species composition differed between aspects and changed during the year, especially on north aspects where Paspafum dilatatum and pasture dead matter content varied inversely with the amount of legumes and other grasses. A highly significant negative relationship Ibetween land slope and production accounted for 22% of the variability in pasture growth rate on both north and south aspects over the major part of the year excluding late autumn and winter. Soil moisture and grass temperature differed with aspect and also in their individual effect on pasture growth during the year. Temperature level and difference between aspects was found to be affected to a large extent by cloud cover, especially during winter on the south aspect (warmer than in clear weather) and during summer on the north aspect (cooler than in clear weather).