16 



PRACTICE 7. 



NITRIFICATION. 



Dilute 20 cc. of the standard ammonium sulfate solution to 500 cc., 

 add. 3 gm. of dipotassium phosphate, 5 gm. of calcium carbonate, and 

 about 2 gm. of fresh rich garden soil. Mix well, let settle, and draw off 

 two loo cc. portions. 



Place 500 gm. of clean washed and dried white sand in a percolator. 

 Upon this pour 100 cc. of the above solution and immediately wash the 

 sand with about 500 cc. of ammonia-free water, collect the washings and 

 make up to exactly 500 cc. Place 250 cc. portions in copper flasks, add 10 

 cc. of alkali and determine the nitrogen in the usual way. Compare the 

 amount of nitrogen distilled as ammonia with that originally applied in 

 the ammonium sulfate. 



Titrations (1) cc. NH 3 



(2) cc. NH 3 



Average cc. NH 3 



Mg. N found 



Add the other 100 cc. portion of ammonium sulfate solution to 500 

 grams of clean, washed and dried sand in a percolator and allow to stand 

 in a dark place at warm room temperature for four weeks. Then wash 

 out and determine the ammonia nitrogen as directed above. 



Titrations (1) cc. NH 3 



(2) cc. NH 3 



Average cc. NH 8 



Mg. N found 



Percent N nitrified 



What change has been brought about and how? 

 Explain fully. 



