Agricultural Topography and Management in New Zealand

  • Topography in New Zealand Agriculture

    • Importance of hill country farming:
    • Majority of New Zealand farming takes place in hilly terrains.
    • Pastures predominate landscape compared to other countries where flat land is common.

  • Key References:

    • New Zealand Pasture and Crop Science textbook, Section 3.8.
    • Breanna Taylor's honors project paper on suppressing gorse seedlings after the Port Hills fire in the Journal of New Zealand Grasslands.

  • Influence of Topography:

    • Defines climatic conditions (temperature and moisture), soil quality (edaphic factors), and biological components (grazing effects).
    • Effects vary with altitude and latitude across different landscapes.

  • Hill Country Farming Development:

    • Subdivision: Crucial for effective grazing management; develop prime land (usually flatter) first.
    • Utilize high stocking rates with hoof and tooth method to manage weed growth, e.g., manage scrub and brown top vegetation.
    • Essential to ensure a consistent water supply to facilitate grazing.
    • Photos depict rolling hill country with challenges of thistles and rushes from grazing livestock.

  • Four S's for Success in Hill Country:

    1. Find the Right Soil Nutrients:
    • Focus on phosphorus and sulfur levels with recent considerations for lime and molybdenum.
    • Fertilizer management aims to bolster clover growth, which is crucial to pasture health.
    1. Pasture Management:
    • Strategies include over-sowing with clover and cocksfoot in drier areas to enhance pasture biodiversity.
    1. Temperature and Altitude Effects:
    • Higher altitudes experience reduced pasture production due to lower temperatures (e.g., yield drops from 6000 kg to 2000 kg from 300m to 1100m elevation).
    • Rainfall patterns change, influencing moisture retention; higher altitudes tend to be wetter.
    1. Aspect Influence:
    • Shady aspects (southern slopes) retain moisture longer than sunny aspects, affecting species composition.
    • Different evapotranspiration rates between north and south slopes (e.g., 1.3mL/day vs 0.07mL/day) influence pasture growth.

  • Species Composition:

    • Drought-tolerant species more prevalent on sunny slopes which experience higher temperatures and lower moisture retention.
    • Genetic composition reflects environmental adaptability (e.g., bromes and cocksfoot on sunny vs wetland species on shady slopes).

  • Fertility and Nutrient Distribution:

    • Grazing behaviors affect nutrient allocation (e.g., sheep camp at the tops, leading to increased fertility zones).
    • Fertility can create richer zones that favor annual grasses and thistles, while lower fertility areas may struggle.

  • Topography and Fire Effects:

    • Burning Practice:
      • Intended to eliminate gorse and rejuvenate pasture.
      • Post-burn recovery shows varied response by species; perennials tend to recover more effectively.
    • Monitoring with drone-seeded overseeding of Italian ryegrass to combat gorse regrowth shows effectiveness.

  • Conclusion:

    • Effective agricultural development in New Zealand hill country is complex and requires an understanding of topography, climatic influences, species interaction, and nutrient management.
    • Successful management incorporates subdivision, the use of legumes, and holistic grazing practices to foster sustainable pasture growth.