2 BULLETIN" 441, U. S. DEPARTMJ^N-T OF AGEICULTTJRE. 



the staff of the Office of Soil-Fertility' Investigations and others/ so 

 its repetition here is not deemed necessary. 



Working with soil extracts ^ 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 miUion of the element 

 manganese. 



Schreiner and Sullivan ^ 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 shght oxidative power, oxidation was but sHghtly 

 increased until certain kinds of organic matter, such as citric, mahc, 

 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 in organic matter. 

 The physical condition of the soil is rather j)oor, 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 in different plats. The soil 

 is of an acid nature. 



The ground on which these experiments were made consists of two 

 paraUel 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. V. S. Dept. Agr., Bur. Soils Bui. 

 73, 57 p. 1910. 



KeUey, W. P. The function and distribution ot manganese ui plants and soUs. Hawaii Agr. Exp. 

 Sta. Bui. 26, 56 p. 1912. 



2 Skinner, J. J., Sullivan, M. X., et al. The action of manganese ia soUs. U. S. Dept. Agr. Bui. 42, 

 32 p. 1914. 



