42 The Influence of Potsherds on Nitrification 



15 30 14 29 13 28 13 28 12 27 12 27 11 26 10 25 

 Julj' Aug. Sept. Oct. ,Xov. Dec. Jan. Feb. 



1916 1916 1917 



Fig. 3. Nitrates in the soils of 4 ft, gauges. 



12 27 12 27 11 26 10 25 



Nov Dec. Jan. Feb. 



1910 1917 



-70 



Fig. 4. Air temperature and river level. 



