PRACTICE VI 



DETERMINATION OF NITROGEN IN SOILS 



Each group of students will work upon one stock soil, such as the 

 following : 1 



1. Surface of gray silt loam. 5. Surface of black clay loam. 



2. Subsoil of gray silt loam. 6. Subsoil of black clay loam. 



3. Surface of brown silt loam. 7. Sandy soil. 



4. Subsoil of brown silt loam. 8. Peaty soil (use 2 g.). 



For all soils except peat weigh out 10 g. of air-dry soil and use 

 10 cc. of standard hydrochloric acid in the receiver. 



(1) Titration cc. XH 3 



(2) Titration cc. NH 3 



Av cc. XH 3 



Per cent N 



Calculate the results obtained, and with these record the results 

 obtained by three members of each group as indicated upon the 

 following page. 



Assuming that there are 2,000,000 pounds in an acre to the depth 

 of 6 inches, how many pounds of nitrogen are there in this plowed 

 soil'? How many 100-bushel crops of corn will this produce if the 

 total crop is removed ? 



1 These are types of soil which can easily be found in almost every state in the 

 North Central group ; but in other sections the important and extensive type soils of 

 the state should be substituted for some of these. 



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