Food for 

 Plants 



44 



The point of importance, therefore, is the price 

 that is paid for the organic forms of Nitrogen. In the 

 above discussion, it has been assumed that the organic 

 Nitrogen contained in the fertilizers has been derived 

 from dried blood, or from similar materials. As a 

 matter of fact, however, dried blood does not con- 

 stitute even a large proportion of the organic Nitrogen- 

 ous materials used — the bulk of the Nitrogen being de- 

 rived from products of a lower grade. Various kinds of 



Hedge of California Privet Three Years Old, Fertilized for 

 Three Years by Nitrate. New Jersey. 



meat and bone, tankage, dried fish, fish scrap, cottonseed 

 meal, garbage-tankage, leather meal and even peat, 

 being used to supplant products of the higher grade. 

 These Nitrogen-carriers, have been shown to have a 

 wide range in availability, the leather and peat rating 

 in availability as low as 4 in comparison with Nitrate 

 at 100 and barnyard manure as low as 3. 



It may be urged, first, that these products possess 

 some value as sources of Nitrogen and, second, they 



