2 BULLETIN 42, U. S. DEPARTMENT OF AGRICULTURE. 



per cent MnO, the average content being 0.071 (instead of 0.20 per 

 cent given in the circular) . 



This element is universally found in plants, frequently in relatively 

 large quantities, exceeding often that of the related element iron. In 

 the ash of beech leaves was found in one case 11.25 per cent Mn 3 4 

 and only 1.07 per cent Fe^g. 1 Manganese has been found in the 

 various organs; young shoots and leaves are especially rich in the 

 element. 2 The conifers have a higher per cent than have leaf -bearing 

 trees. One case has been reported where 35 per cent was found in 

 the ash of pine needles and 41 per cent in the ash of pine bark. 3 

 Kelley 4 has reported the analysis of a large number of plants grown 

 on two different soils. The ash of these vary in manganese content 

 from a trace in the case of wheat straw to 1.70 per cent Mn 3 4 in 

 pineapple leaves grown on normal soil. Of plants grown on soil high 

 in manganese content, the analysis showed the ash of wheat straw to 

 contain 0.22 per cent and pineapple leaves to contain 2.41 per cent, 

 the highest quantity being in the leaves of Waltheria americana, which 

 contained 8.70 per cent Mn 3 4 . While manganese is found universally 

 distributed in plants and exists in most soils, it is recognized that it 

 does not serve directly in a plant-food capacity. Plants have been 

 raised in water cultures to perfection in the absence of any added 

 manganese. Nevertheless, manganese salts have been frequently 

 recommended in soil work for the increase of crop production, either 

 as soil amendment or fertilizer, although its action is neither well 

 understood nor its effects on crop yield very definitely determined, 

 the results in the literature being often contradictory. Its recent 

 prominence as a catalytic fertilizer makes a knowledge of its action 

 in soils of considerable interest. 



REVIEW OF EARLIER EXPERIMENTS WITH MANGANESE IN SOIL 



CULTURE. 



The study of the effect of manganese on growth has been made 

 almost entirely in foreign countries. The application of manganese 

 compound in soil culture has given widely different results. In 

 some cases there were beneficial actions, in others harmful, -and in 

 a large number of the experiments the results were negative. 



Of the various forms of manganese, the sulphate and chloride have 

 been used most by investigators. Nagaoka 5 working with the cul- 

 ture of rice in frames in paddy fields found that manganese sulphate 

 added at the rate of 25 kilos of Mn 3 4 per hectare (about 20 pounds 



i Wolff, E.,loc.clt., 1,121. 



» Pichard. Comp. rend., 126, 550 (1898). 



1 Schroder, T., Forstchemische und pflanzenphysiologische Untersuchungen, Thorand, 1878. 



4 Kelley , W. P., The function and distribution of manganese in plants and soils. Bui. 26, Hawaii Expt. 

 Sta. (1912). 



6 Nagaoka, M., On the stimulative action of manganese upon rice. Bui. Col. Agr. Tokyo, 5, 469 

 (1902-3); 6, 135 (1904-5); 7, 77 (1906-1908). 



