]913] Burgess: Beduction Methods for Soil Nitrates 55 



Test of the Reduction Method With Large Quantities of 



Nitrate 



In soil work considerable amounts of nitrates are often 

 encountered. The first series of experiments were thus made 

 to determine whether or not the reduction method would prove 

 accurate in the presence of from 30 to 60 mgs. of nitrate nitrogen. 



The results set forth in the following table are averages of 

 several analyses made at the same time and under similar condi- 

 tions. A comparison is also made here of the reduction method 

 with the phenoldisnlphnnic acid method. 



TABLE I 



A Comparison of the Beduction Method and the Phenoldisulphonic 

 Acid Method With Large Amounts of Nitrate Nitrogen 



We thus see that the reduction method, even where no salts 

 are present, but where large amounts of nitrates are found, is 

 slightly more accurate than the phenoldisulphonic acid method. 



The Effect of "Alkali" Salts on the Reduction Method 



Method 



As stated above, in our research work on different "alkali" 

 problems in soils, more especially in soil bacteriology, and plant 

 physiology, considerable amounts of salts are often used in soils 

 in which later the nitrate content must be ascertained. Besides 

 it is frequently necessary to determine nitrates in soils of the 

 arid regions which contain considerable quantities of "alkali." 

 It is important therefore to ascertain if the method herein pro- 

 posed is in any wise affected by salts. Therefore the following 

 tests were carried out. The salts employed were "Baker's An- 



