Influence of some soil and pasture components on the growth of hill country pastures 1. Winter and spring production

Abstract

Aspect and land slope have a major influence on winter and spring pasture growth. Possible physiographic, soil, and plant factors contributing directly to this influence were examined across a range of microsites in steep North Island hill country. As land slope increased, organic and inorganic nitrogen in the soil decreased. Similarly, organic carbon decreased and this was associated with a decline in soil water-holding capacity. Soil water potentials were high during winter and spring and showed little effect of aspect. Pasture growth was greater on warmer, north-facing than on colder, south-facing aspects, the difference being less for ryegrass-dominant sites than for browntop associations. Where long-term site conditions (e.g., slope, fertility, moisture) allow the development and maintenance of perennial ryegrass populations, greater winter and spring growth rates were recorded. The importance of developing an effective N cycle based on stable legume populations for improving soil N status, ryegrass content, and cool-season pasture production in hill country is highlighted.