The microflora of the rhizosphere with special reference to the oxidation of manganese.

Manganese is widely distributed in soil. It occurs in all soils, though usually in low concentrations, and is found in deposits as the ore, pyrolusite. Analyses of plants (25, 33, 37, 39, 40, 44) show that it is absorbed by them and stored in the leaves and in the germ and pericarp of the seeds. That plants absorb manganese has been known since Scheele’s work in 1774, but recently it has been shown that different quantities will be absorbed under changing conditions (17,52); that the amounts absorbed will differ with various stages in the development of the plant (68); and, that the amounts required by different species will vary (36,37). Many workers (1,7,10,13,16,18,20,22,23,24,29,34,35, 37,40,41,42,43,45,54,55,57,58,60,63,75) have shown that manganese in certain concentrations stimulates the growth of higher plants, yeasts, and fungi; that to obtain maximal growth it must not be omitted from the nutrient solution; and that it cannot be replaced by any other element. [...