Future Directions for Dryland Soil Management Under Direct Seeding Techniques - an Australian Perspective

摘要

Tillage practices associated with seedbed preparation for crop establishment have contributed to land degradation in the cropping zones of southern and central NSW, Australia, as elsewhere. The links between tillage practices and soil structure decline, salinisation, acidification, erosion, declining organic matter levels and declining soil hydraulic properties have been well documented, contributing to a decline in catchment health over many decades. The potential benefits of direct seeding techniques have also been well established, but Australian experience suggests that direct seeding alone may not be sufficient to reverse this trend. Wider environmental issues are also involved, such as increasing levels of greenhouse gasses. This paper reviews historical and current data on the impact of seeding method on soil quality, confirming that direct seeding techniques create positive benefits to soil quality in an acceptable time frame. From this, critical success factors and key indicators are evaluated, including organic carbon content 0 - 50 mm, soil hydraulic properties, and macropore development and continuity. For landholders and advisors, tactile/visual indicators and field assessments are needed. It is recommended that direct seeding techniques be integrated into the design of farming systems, as part of a 'best practice' approach to soil management and catchment health. Such an approach requires landholders to know the properties of their soils. Landholders should strive to maximise ground cover, minimise soil disturbance, maximise vegetative plant growth, and minimise soil compaction by both machines and livestock. Barriers to adoption of direct seeding techniques need continuing investigation.