Abstract :
Relations between the geochemical nature of soils and their parent materials and the occurrence of nutritional deficiencies and excesses in grazing livestock have been documented since the 1960s and earlier, with notable work in Australia, New Zealand, United Kingdom, Ireland, USA and the Soviet Union. Studies at Imperial College London, into the development of regional geochemical mapping techniques as a means of delineating nutritional problems commenced in the 1960s and have continued to the present. Research has mainly focussed on deficiencies of Cu, Co and Se in cattle and sheep, and the role of Mo and S in the soil/plant system in both clinical and sub-clinical hypocuprosis in cattle. Exposure to heavy metals, in particular Pb, Zn, Cd and the metalloid As have also received attention in areas contaminated by past mining and smelting activities. Soil and plant factors influencing the dietary supply of both essential trace elements and toxic metals have been studied, including their speciation and bioavailability. Soil ingestion has been recognised as an important exposure pathway of heavy metal contamination to grazing cattle, and as an antagonist of Cu supply and a source of dietary Co in sheep. Relations between soil geochemistry and the mineral status of wildlife species, in particular impala and black rhinoceros, have been established in Kenya and recent work, presented elsewhere in this Symposium, has concerned the supply of nutrients to the Roosevelt sable in Kenya. The compilation of regional and national multi-purpose geochemical atlases, based on the systematic sampling of soils or stream sediments, is now recognised as a priority in many countries of the developed and developing world. This paper explores the opportunities for future research into the application of geochemical maps for the optimisation of land use, efficient livestock production, and improving conservation of wildlife.
