OCCUEBENCE OF MANGANESE IN SOIL AND ITS EFFECT ON GRASS. 357 



20 fbs. sulphate of manganese per acre, applied after the 

 seeds had germinated, and although the season was not a 

 favourable one, and the figures are not conclusive, and in 

 some cases the treated plots did not yield any better than 

 the untreated, he finds that on the average the yield from 

 the untreated plots is somewhat better. In the pot-experi- 

 ments also, Mr. Potts reports a slight average increase 

 with wheat, tares, and oats on treating the soil with '001, 

 *002, and *005°/° manganese sulphate. Oats are stated to 

 show the greatest increase. 



In larger quantities manganese compounds have been 

 found to act as plant-poisons. G. Salomone 1 finds as the 

 result of experiments in the field, that 50 kilogrammes of 

 manganese sulphate per hectare (about 44 ihs per acre) 

 produce the most favourable results in the case of wheat. 

 Above this quantity the development of the plant is retarded 

 and the proportion of grain and straw diminished. With 

 80 to 85 kilos per hectare the plants died before flowering, 

 and with 90 kilos per hectare the plants only attained a 

 height of a foot and then suddenly wilted. He finds also 

 that the toxicity of the different salts of manganese in- 

 creases in those in which it acts as an electronegative 

 element, being greatest in the manganates and perman- 

 ganates. 



A series of interesting experiments has been published 

 by W. P. Kelley 2 of the Hawaii Experiment Station, into 

 the effect of manganese upon the growth of pineapples. He 

 finds that certain areas of the soil in Hawaii on which the 

 plants do not develop, turning yellow in colour and pro- 

 ducing inferior fruit, always contain excessive quantities 



1 Le Staz. Sper. Agric. Ital., Vol. xxxviii, p. 1015, and Vol. xl, p. 97. 

 In the first paper will be found a good bibliography of previous work on 

 this subject up to 1905. 



2 Journal of Industrial and Engineering Chemistry, Vol. i, No. 8, p^ 

 533 (August 1909). 



