SOIL SODICITY IN VICTORIA

This paper gives a broad overview of the distribution and agricultural importance of sodic soils in Victoria. Sodic soils are estimated to o ccupy at least 13.4 Mha, representing at least 73% of Victoria's agric ultural land. Most of this land is used for dryland farming; about 85% of the cropped land and 66% of the land sown to dryland pastures occu rs on sodic soils. The largest sodicity class is 'alkaline sodic', dom inated by a diverse range of soils (red duplex, yellow duplex, calcare ous earths and self-mulching cracking clays). Alkaline sodic soils com prise half of the total agricultural land area, or about 24% of the ar ea of land currently used for dryland cropping and 21% of the land und er sown pasture. Land degradation problems are recognized as affecting most agricultural land in Victoria, and to be substantially limiting its productivity. The nature, extent and severity of the various forms of land degradation are a consequence of both intrinsic soil properti es and of management practices. There is an urgent need to improve cur rent farming practices to prevent further deterioration of the soil re source. Existing knowledge of the behaviour of sodic soils under both dryland and irrigated agriculture is reviewed. It is concluded that su bstantial gains in productivity are possible, but will require effecti ve collaboration between soil scientists, agronomists, and land manage rs. Collation and integration of current knowledge on the properties a nd management of sodic soils in Victoria, and the acquisition of addit ional relevant information by targeted long-term research is required. Key issues for future research are identified.