CAN WE MANIPULATE THE ANNUAL PATTERN OF PASTURE GROWTH?

Abstract

The annual pattern of pasture growth rates on two Rangitaiki plains dairy farms is examined. The cyclical pattern of growth is largely determined by temperature, moisture and light levels, but modified by changes in the relative importance of individual pasture species through the year. Within this pattern, variation from year to year is least during the spring, apparently related to the flowering period of ryegrasses, and greatest in the summer-autumn period. Animal production systems are often constrained by shortfalls in late winter-early spring feed supplies and the variability of summerautumn growth. Grazing management has a limited potential for directly modifying the pattern of pasture growth. However, application of nitrogen fertilizer can increase late winter growth rates to help overcome feed deficits, while the use of specialized pastures can ensure more reliable summer growth.