26 



PRACTICE 12. 

 DETERMINATION OF NITROGEN IN SOILS. 



Each group of students will work upon one of the following : 



1. Surface of gray silt loam. 



2. Subsoil of gray silt loam. 



3. Surface of brown silt loam. 



4. Subsoil of brown silt loam. 



5. Surface of black clay loam. 



6. Subsoil of black clay loam. 



7. Sandy soil. 



8. Peaty soil (use 5 gm. soil and 20 cc. standard HC in receiver.) 

 For all soils except peat weigh out 10 gm. air-dry soil and use 10 cc. 



of standard hydrochloric acid in the receiver. 



Titrations (1) cc. NH 3 



(2) , cc.NH 3 



Average cc. NH 8 



Percent N 



Calculate the results obtained and with these record the results ob- 

 tained by three members of each group as indicated upon the following 

 page. 



Assuming there are 2,000,000 Ib. in an acre to the depth of seven 

 inches, how many pounds of nitrogen are there in this plowed soil? How 

 many loo-bushel crops of corn will this produce if the total crop is re- 

 moved ? 



