352 



ANNUAL REPORT OF THE 



Table VIII. 



Off. Doc. 



Nitrogen as Nitrates in Drainage Waters, Broadwalk Field at Dif- 

 erent Seasons. Average of three Years in parts Per Million of 

 Drainage Water. 



o 



Character of the Manuring of the Land. 



6. 

 6, 



7, 

 8, 

 15, 

 17, 

 18, 

 2, 

 19, 



Mixed mineral manures. 

 *200 lbs. ammonium salts and minerals. 

 *40O lbs. ammonium salts and minerals. 

 *600 lbs. ammonium salts and minerals. 

 t400 lbs. ammonium salts and minerals. 

 400 lbs. ammonium salts alone. 

 Mixed mineral manure. 

 Barn yard manure. 

 Rape cake. 



•Applied In the spring. 

 fApplied in the fall. 



The use of large quantities of ammonium salts, or of nitrate of 

 soda at the time of spring seeding results, as the last table shows, in 

 an immediate increase of nitrates in the drainage waters. 



There is ever}' reason to believe that ammonium salts, w^hen ap- 

 plied to the soil, are very rapidly converted into nitrates, and in this 

 form washed out of the soil. The same loss would follow similar 

 applications at the time of autumn sov,'ing as shown by the results 

 from Plot 15, given in the last table. 



Hence whenever it becomes necessary to use ammonium salts or 

 nitrates as a crop stimulant, tliey should be applied in small quanti- 

 ties while the crop is growing. The custom of introducing nitrate of 

 soda with the seed is accordingly a most wasteful operation. 



T/ie Amounts of Nitrates Lost m the Drainage. 



It is calculated that the Kiver Khine discharges daily into the 

 ocean 220 tons of nitrates, calculated as nitrate of soda; the Seine 270 

 tons, and the Nile 1,100^^ tons. 



Since the great bulk of this comes from nitrates produced in the 

 soil it is easy to form some idea of the tremendous losses of this the 

 most valuable of all plant nutrients. 



From what has already been said it is seen: 



1. That given equal rainfall, the amount of nitrates lost in the 

 drainage is greater in sandy than in heavy soils; and in direct ratio 

 to the porosity of the latter. 



2. That the loss by drainage, and hence the corresponding loss of 



