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The search for economically viable ley pastures in the Australian tropics is an attempt to emulate the successful ley farming systems, based on subclover and wheat, in regions with Mediterranean and temperate climates in southern Australia.

The paper examines experimental legume ley pastures in the semi-arid tropics from four points of view, viz - initial establishment and re-establishment of the various ley species after a crop; the contribution of biological nitrogen from the ley to the farming system; the control of pasture species during the crop phase; and the feeding value of ley pastures and crop residues to grazing cattle.

Management problems highlighted by the research on experimental ley pastures include: grass dominance in the pasture; the extremely rapid decomposition of legume residues and the resultant leaching of mineral nitrogen beyond the root front of the developing crop; and the lack of sufficient crop and pasture residues in some seasons for successful crop establishment using no-till methods.

The adequacy of existing genetic resources for ley pastures in this region, the biological and economic sustainability of tropical ley systems, and the prospects for commercial use of the experimental results, are also examined.