PRACTICE XVI 



THE EFFECT OF LIME UPON NITRIFICATION 



Place 500 g. of a worn acid soil in a percolator. Upon this pour 

 100 cc. of a dilute ammonium sulfate solution (40 cc. of the standard 

 ammonium sulfate solution plus 460 cc. of water). Allow to stand 

 one hour, wash with about 500 cc. of ammonia-free water, and deter- 

 mine the total nitrogen * as directed in 3, Practice XXIV. 



Titrations (1) cc. XH 3 



(2) cc.XH 3 



Av cc. XH 3 



X found mg. 



Into one percolator bring a second 500 g. of the worn acid soil, 

 and into another a third with which 5 g. of finely ground limestone 

 has been thoroughly mixed. To each of these add 100 cc. of the 

 ammonium sulfate solution used above, and allow to stand in a dark 

 place at room temperature for six weeks. Then wash out and deter- 

 mine the total nitrogen as directed above. 



Without lime- With lime- 



stone stone 



Titrations (1) cc. XH 3 



(2) cc.XH 3 



Av. cc. XH 3 



X found mg. 



Per cent X nitrified 



Explain the effect of the limestone. 

 What is one effect of liming worn lands ? 

 Does nitrification enrich the soil ? 



1 See " Soil Fertility and Permanent Agriculture," pp. 562-563. 



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