104 



Physics of the Soil. 



120. Less of Nitrates from Fallow Ground During Winter 

 and Spring. A field which has been kept fallow during a 

 whole season and cultivated either once per week or once in 

 two weeks had the nitrates determined in it on August 25 

 and again the next spring, April 30. The field was di- 

 vided into nine plots and the nitric nitrogen was deter- 

 mined in each one to a depth of four feet on both dates. 

 The results are given in the next table. 



Table showing the amount of nitric nitrogen found in fallow 

 ground after the leaching of winter and early spring. 

 Pounds per million of dry soil. 



It is clear from this table that however large the leach- 

 ing may have been it was not enough to prevent the nitrates 



FIG. S3. Showing the difference in the amount of nitrates in the surf.ieo 

 four feet of fallow ground, the succeeding spring, and that upon \vbicb 

 crops had been grown. 



