28 



Vegetation Experiment to Determine the Nitrogen Activity of Several 

 Fertilizers Found in 1913 Inspection, and a Comparison with the 

 Laboratory (Alkaline Permanganate) Method. 



A few fertilizer manufacturers have expressed the belief that the 

 alkaline permanganate method was not a reliable one in detecting 

 the presence of low grade organic ammoniates. Although the 

 method has been successfully checked several times with vegetation 

 experiments conducted in other experiment stations, it was thought 

 best to conduct a very careful vegetation test in our own greenhouses 

 during the winter of 1913 in order to throw more light upon this im- 

 portant matter. 



The nitrogen sources used were in a large measure derived from 

 the water insoluble portion of the nitrogen content in several of the 

 mixed commercial fertilizers taken from the 1913 fertilizer inspection, 

 and included not only some of the brands noted as suspicious, but also 

 other brands the quality of whose nitrogen was not in any way ques- 

 tioned. 



The following brief data may be noted regarding the outline of 

 the experiment: 



Soil: The soil for the experiment was selected on account of its 

 nitrogen deficiency and was taken from the Station south soil test 

 plot No. 11. It was found to contain by actual analysis .125 per 

 cent total nitrogen. The pots held about 43 pounds of soil and 

 were filled with a mixture composed of one part of soil and two parts 

 of sifted sand which carried .0039 total nitrogen. 



Organic Matter: The organic matter necessary to produce nor- 

 mal conditions was furnished by an application of 100 grams of de- 

 composed straw; (this would be equivalent to about 4 cords per acre). 



Lime: Each pot received 27.52 grams of marl (equivalent to 

 2 tons per acre). 



Fertilizer: The fertilizer and lime were mixed thoroughly with 

 the soil in each pot. The source of each fertilizing ingredient was 

 as follows: 



Potash: Each pot received 10 grams of high grade sulfate of 

 potash testing 49.92 per cent K2O; (this would be equivalent to 1320 

 pounds per acre). 



Phosphoric Acid: Each pot received 18 grams of acid phosphate 

 testing 14.57 per cent available phosphoric acid and 18 grams of basic 

 slag phosphate testing 14.80 per cent phosphoric acid, (equivalent to 

 2800 pounds of acid phosphate and 2800 pounds of basic slag phos- 

 phate per acre). 



