68 



T. Lyttleton Lyon and James A. Bizzell 



Soil samples for moisture and nitrates were taken to a depth of ten 

 inches except on the cultivated plats, on which the surface two inches was 

 removed before boring and the samples were taken to a depth of ten inches 

 under the layer removed. The reason for removing the surface two inches 

 on these plats was to eliminate from the samples the loose, dry layer, in 

 which nitrate formation would not be expected to proceed under the same 

 influences that operate in the moist soil below. In Diagram XVI is shown 

 the course of the nitrates under the cultivated maize and under potatoes 

 and oats. 



B£FO/^£ 

 PLANT/NG 



JUN£ 



JULY 



/AUGUST SEFT 



OCT 



//O 



/oo 







y 



V 







90 







y 









ao 







/ 



7 







70 















60 













^ 



50 













^ 



40 















DIAGRAM XVII. — Relative nitrate content of soil under maize mulched, 1912 



The nitrate content and the moisture content of the soil on the planted 

 and unplanted sections of all plats are sho^vn in tables 21 and 22. The 

 characteristic relationship between the crop and the nitrate content of the 

 soil is again apparent in the former table, nitrates being higher under maize 

 than under potatoes during the active growing period and being lowest 

 under oats. 



Nitrates are sometimes higher in the soil under maize than in the 

 unplanted soil on the mulched plats; but the nitrates are .so high in the 



