White clover, red clover, lucerne and sainfoin were grown in the field, and the mineral composition and cation/anion balance of the herbage were determined on samples taken at advancing stages of growth on eight occasions from 29 April to 18 July.The elements which showed the greatest differences in content between species were calcium, sodium, and molybdenum. White clover was consistently higher than the other species in nitrogen, phosphorus, chlorine and molybdenum. Sainfoin was consistently and substantially lower in calcium and sodium than the other species.Evidence based on the total contents of cations and inorganic anions and on determinations of ash alkalinity indicated that white clover and red clover had the highest contents of organic acids, sainfoin having substantially lower, and lucerne intermediate, levels.