CONSERVATION TILLAGE AND SEEDING SYSTEMS IN THE SOUTH-PACIFIC

The preservation of the non-renewable soil resource is a vitally important aspect of the long-term development of conservation tillage and pasture production systems in the Pacific region. Improved grasses and legumes are commonly sown in New Zealand and Australia to increase pasture and animal production. Pastures sown by conventional cultivation are becoming increasingly expensive and time consuming. Crops and pastures sown in rotation by conservation tillage methods (including no-tillage) are becoming more common. This paper summarises major soil and plant management factors and their interactions with the environment and machinery, which improved biological reliability and sustainability of no-tillage in the Pacific region. Collectively the research has demonstrated that the habitat of seeds under no-tillage together with their resulting seedling microenvironments, are pivotal to yield and are influenced by micromanagement of the soil, surface residues and soil fauna in the sown slot zone. These parameters are themselves influenced by the action and the design of seed drill openers. Soils under sustained no-tillage systems, involving organic matter return, contain vapour-phase moisture even in dry soils, often together with oxygen-enhanced diffusion potential largely unmatched by tilled soils. Description of technology designed to create and exploit such environments is made. The causal processes of failures and the high biological risks associated with conventional no-tillage drills are also explained. Provided appropriate pest control measures are taken, this technology has resulted in biologically predictable, reliable and sustainable crop establishment and production systems.