Abstract:
Dryland salinity and water quality problems occur in the Great Plains and cornbelt regions of the United States of America (USA) and southern Australia due to the replacement of native perennial systems by annual species. We outline the hydrological effects of selected farming systems in both countries and review progress towards development of new perennial systems with potential to reduce dryland salinity effects. In Australia, development and large-scale trialling are further advanced than in the USA. In both countries there are usually insufficient benefits to farmers to adopt perennials at the scale needed to reduce environmental effects. Perennials are generally more complex to manage and, for successful adoption, greater skills are often required than to manage annuals. Experience from the Conservation Reserve Program in the USA to encourage conversion of cropland to perennials indicates that the scale of landscape change achieved (in the order of 5%) is still low. Lessons learnt in both countries from experiences include: (1) careful thought as to where perennials are most needed (targeting); (2) plant development programs targeted at key environments; (3) involvement of farmers in research at the outset to ensure that systems developed are profitable and adoptable; (4) the need for a trialling and learning program; (5) appropriate choice of policy tools to maximise environmental outcomes.