SUSTAINING MULTIPLE PRODUCTION SYSTEMS .5. SOWN PASTURES FOR MARGINAL CROPPING LANDS IN THE SUBTROPICS

Fertility and structure of surface soil is declining throughout the marginal dryland croplands of eastern Australia. The incorporation of a pasture phase in the cropping sequence appears to be the most promising option for developing a sustainable cropping system. However, special problems currently restrict the use of sown pastures in these lands in sub-tropical Queensland and NSW. For much of the region, productive and persistent pasture species have been identified. These include the native grasses, Astrebla lappacea and Dichanthium sericeum. Perennial grasses are still needed on the lighter textured infertile soils and there are still no adapted summer growing legumes for frost prone areas. Unreliable establishment is currently the main technical constraint limiting wider use of the available pasture species. Strategies for overcoming this constraint are discussed and include decision support packages using climatic and biological models, improving establishment by means of aerial seeding, mulches and stubbles, and management for improving the supply of soil moisture.