INJURIOUS EFFECT OF SULFATE OF AMMONIA. 



133 



results given in Table IX. The crops were subsequently analyzed for 

 total nitrogen, iron oxide, silica and manganese, the results of which are 

 shown in Table X. 



Table IX. — Grams of Clover obtained from Pot Cultures. 



The soil from plot 6 was noticeably inferior in productivity to that 

 from plot 7, when used in the pots as well as in the field. This is shown 

 by comparing pot 1 vdth. pot 7 and pot 2 with pot 8. 



Extracting the soil with water diminished the crop, as shown in pots 3 

 and 4, indicating that soluble plant food was removed by the water, 

 whether toxins were removed or not. 



The addition of manganese sulfate to the soil produced a marked de- 

 pression in yield on both soils when unaccompanied by calcium carbonate, 

 while the employment of the calcium with the manganese resulted in 

 each instance in an increase of crop beyond that produced by the calcium 

 carbonate alone. These results are in accord with field experiments lately 

 reported by Skinner and Reid.^ 



Chemical analysis of the clover was confined to the crops from the soil 

 of plot 7. Manganese was found to increase in the clover tops nearly in 

 proportion to the quantities added to the soil. The presence of calcium 

 carbonate in the soil did not prevent the absorption of the manganese to 

 a marked extent; therefore it would seem to have been an antidote for 

 the poisonous effect of -the manganese witlain the plant. 



The consistent increase of the percentage of nitrogen in the crops 



Action of Manganese under Acid and Neutral Soil Conditions," Bui. No. 441, U. S. Dept. 



Agr., 



