D.L. LLOYD, K.P. SMITH, N.M. CLARKSON, E.J. WESTON and B. JOHNSON

Queensland Department of Primary Industries, Towoomba, Queensland, Australia.

Abstract

During the 1990s, wheat protein and yield from many cropping soils (mainly vertisols) in the subtropical wheat belt will continue to decline as soil fertility is gradually depleted. One option for maintaining crop yield and quality is ley farming. It has had limited application when soil fertility has been adequate for crops and where the use of N fertiliser has been a viable option. Temperate legumes of the genus Medicago (lucerne and annual medics), and tropical grasses are available for use in leys, but there are currently no suitable tropical legumes.
The increases in yield and quality of grain crops recorded after lucerne and annual medic leys in various experiments are reviewed and related to changes in soil N and other factors. Leys provide more enduring benefits to subsequent crops than does the application of fertiliser N.
Ley farming is productive, sustainable, and provides a greater hedge against climatic and economic risks than cropping alone. However, it requires a wider range of management skills, and the challenge remains to stimulate wider adoption of this system.