This thesis was prepared while the author was employed with the Victorian Department of Agriculture at the Mallee Research Station, Walpeup, and at the Longerenong Agricultural College, Dooen. It is in the form of five papers.
The first is a review on the place of barrel medic (Medicago tribuloides Desr) in the Australian wheat belt. The review was published in J. Aust. Inst. Agric. Sci. (1965) 31: 25-35. This provides the background information for the experimental work which is prefaced by a section on climate and soils at Walpeup. The experimental work is concerned with a comparison of four annual medics in pure swards, competition between two annual medics, root studies, and the residual effect of superphosphate on medic pastures in the year after a wheat crop.