the staff of the Office of Soil-Fertility Investigations and others/ so 
its repetition here is not deemed necessary. 
Working with soil extracts 2 from poor, unproductive soils, man- 
ganese salts were found to increase the oxidizing power of the plant 
roots grown therein and increased the growth of the plants. With 
extracts from good, fertile soils the oxidative power of the plants was 
increased, but it was not attended by an increase in growth. This 
was attributed to excessive oxidation in the soil solution. The plant 
tips and leaves themselves showed indications of this excessive oxi- 
dation. Similar results were obtained with soil in pots. The poor, 
unproductive soils were improved by manganese, while good soils 
were not further benefited. The best results were secured with small 
amounts varying from 5 to 50 parts per million of the element 
manganese. 
Schreiner and Sullivan 1 have further pointed out that the oxida- 
tive power of the soil is dependent in part on the nature of the organic 
matter. Thus, when salts of manganese, iron, calcium, etc., were 
added to soil of slight oxidative power, oxidation was but slightly 
increased until certain kinds of organic matter, such as citric, malic, 
tartaric, and glycolic acids or their salts, were added, when marked 
improvement in oxidation took place. 
EFFECT OF MANGANESE ON ARLINGTON SOIL UNDER ACID CONDITIONS. 
Field tests with manganese sulphate were inaugurated on the ex- 
periment farm of the Department of Agriculture at Arlington, Va., 
in 1907. The results secured from 1907 to 1912 have already been 
published. 2 The experiment has been continued with some modifica- 
tion, and the additional data throw considerable fight on the action 
of manganese in soils of this character. The soil in which these ex- 
periments were made is a silty clay loam, low hi organic matter. 
The physical condition of the soil is rather poor, and great care had 
to be practiced in cultivation to keep it in a good physical condition. 
The ground is level and has surface drainage, and the soil throughout 
these manganese plats and their controls is uniform, so the results 
obtained should not be considered as unduly influenced by irregu- 
larities due to nonuniformity of the soil hi different plats. The soil 
is of an acid nature. 
The ground on which these experiments were made consists of two 
parallel strips of land, each 1 rod wide and separated by a 3-foot 
path. Each strip is divided into seven plats of 1 square rod, with 
1 Schreiner, Oswald, and Sullivan, M. X. Studies in soil oxidation." U. S. Dept. Agr., Bur. Soils Bui. 
73, 57 p. 1910. 
Kelley, W. P. The function and distribution of manganese in plants and soils. Hawaii Agr. Exp. 
Sta. Bui. 26, 56 p. 1912. 
5 Skinner, J. J., Sullivan, M. X., et al. The action of manganese in soils. U. S. Dept. Agr. Bui- 42, 
32 p. 1914. 
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