INJURIOUS EFFECT OF SULFATE OF AMMONIA. 131 



Table VIII. — Composition of Clover and Grass Tops and Roots, in Milli- 

 grams per 1 Gram of Dry Sample. 



A study of the table shows that the manganese is taken up to a greater 

 extent by the poor plants, both clover and grass, than by the good plants. 

 The grass seems to be more tolerant than the clover, much more being 

 taken up than by the clover. The results would also seem to indicate 

 that the manganese was not evenly distiibuted throughout the plot, but 

 was more concentrated in spots. As it was rather difficult to find normal 

 clover on the plot it might be said that the spots of better plants were 

 the places of smaller amounts of manganese. A somewhat similar condi- 

 tion has been found by Guthrie and Cohens on a golf green. 



The variations in the iron content of the good and poor plants are so 

 small as to come within the limit of experimental error. The increased 

 amount of silica in the poor plants is probably due to their more mature 

 state. 



As the foregoing experiments with manganese salts in nutrient solutions 

 had shown that calcium carbonate did not counteract the toxicity of the 

 manganese, while in the field an application of lime to soil supposedly 

 infertile because of the presence of manganese salts corrected the toxicity, 

 pot cultures were started to determine whether calcium carbonate in 

 the soil could counteract the toxicity of manganese. 



The soil used was from the unlimed end of plot 7 and the unlimed end 

 of plot 6. As the soil from the unlimed end of plot 6 already contained a 

 large amount of soluble manganese it was first extracted by shaking it 

 for two hours on a mechanical shaker with a volume of water twice that 

 of the soil. The soil was then air-dried and passed through the large 

 sieve (7 holes to the hnear inch). 



» Agr. Gaz. New South Wales, 21 (1910). 



