The mineral composition of lupins. 2. A comparison of the copper, manganese, molybdenum, and cobalt contents of lupins and other species at the one site

Abstract

In a field experiment on an ironstone gravel soil, six lupin varieties from four lupin species were compared with oats, Wimmera ryegrass, Erodium botrys, and three varieties of subterranean clover in their copper contents at four rates of copper application. Manganese, molybdenum and cobalt contents of bulked variety samples were also determined. At rates of up to 20 lb copper sulphate per acre, only subterranean clover and Erodium botrys showed appreciable response in terms of higher copper concentrations in the plants. Lupins had moderate to high contents, but showed little or no response to treatment. Oats and Wimmeya ryegrass maintained very low contents at all rates of application. Among the lupins, the order of copper concentrations in the whole plants, over all treatments, was L. digitatus > L. luteus > L. angustifolius > L. albns. Within L. luteus, the bitter strain wed had a higher mean copper content than the sweet Weiko III variety. Differences were also demonstrated among subterranean clover varieties, Yarloop being higher than Dwalganup or Mt. Barker over all treatments. Subterranean clover had the lowest molybdenum content. Lupins were very substantially higher in manganese than all other species. The particularly high manganese content of L. albus, especially in the seeds, was confirmed. Cobalt levels varied little between species, and were well below the minimum requirement of grazing ruminants. I t was concluded that generalizations as to the relative mineral contents of broad plant groups must be treated with caution when applied to particular species or varieties.