Lucerne is the most tropical of the temperate legumes; it is mainly summer-growing but is much more frost-tolerant than the tropical species. It is an erect perennial with a low-set crown and an extremely deep root system, allowing it to be grown with as little as 550 mm of annual rainfall.
Lucerne needs at least 30 cm of friable loam, and demands high fertility, being very responsive to phosphorus and sulphur; it may grow under slightly acid conditions if top-dressed with lime. Old stands cut for hay can respond to potash.
Lucerne is quite widely used as a pasture plant in sub-coastal and inland subtropical areas. It combines with green panic, buffel grass and rhodes grass to provide protein-rich grazing, but persists for only a few years despite rotational grazing of a system of two weeks grazing and six weeks resting. It is usually lost within a year under continuous grazing.
Stands for hay should be cut when the new shoots are less than 2 cm in length.
Lucerne can be used in ley farming systems to improve the protein status and yield of following wheat crops on the Queensland Darling Downs. The deep root system of lucerne can be used as a 'water-pump' in areas of rising ground water. Conversely on the drier marginal cropping areas of the western downs, lucerne can remove so much soil moisture as to depress yields of succeeding crops.
When some winter rain occurs, lucerne will make a valuable showing and respond better than the summer-growing grasses.
Persistence is a problem in the subtropics because lucerne is attacked by many leaf and root diseases and by insect pests.
Lucerne is sown into well-prepared, fine, firm seed beds in autumn using inoculated seed. Seed rates are 0.5-2 kg when sown with grasses; in pure swards, seed rates should be up to 8 kg/ha in rain-grown conditions and 12-15 kg/ha under irrigation.
All lucernes cultivars are summer-growing, but some are more winter-active. Cultivars can be described as winter-dormant, semi winter-dormant, winter-active, and highly winter-active.
Growth in semi-dormant and dormant cultivars slows down more during the colder months but generally these have lower crowns and are more persistent in dryland grazing systems.
Highly winter-active cultivars will provide year-round feed with only a slight reduction in production in winter, especially under irrigation.
Winter-active cultivars fall between these extremes, with moderate winter growth; they are generally moderately persistent under grazing.
Breeding superior characteristics into lucerne is a major industry and there are numerous excellent cultivars. Recommended cultivars are listed by the state departments of agriculture and by commercial companies, and these should be consulted for suitable selections.
|Creator: Ian Partridge,
Date created: 14 April 1998 Revised: 17 February 2004