MATERIALS FOR FERTILIZERS 149 



this conclusion and without bias or prejudice, let it be attempted 

 to draw up a statement as to what constitutes a fertilizer and what 

 materials may be included under that head. 



A fertilizer is any substance, subject to the qualifications given 

 below, which furnishes to the soil any one or more of the following 

 chemical elements nitrogen, phosphorus, potassium, sulphur, and 

 calcium; or which furnishes organic matter. The substances con- 

 taining the chemical elements named must, in addition, possess the 

 following qualifications : 



1. They must contain, if they are largely insoluble in water, no 

 less than the following percentages of their respective elements or 

 compounds: 3.0 per cent nitrogen, 20 per cent phosphoric acid, 20 

 per cent potassium oxide, 20 per cent sulphur, and 35 per cent 

 calcium oxide. 



2. They must contain, if they are largely soluble in water, no 

 less than 1 per cent nitrogen (as nitrate or ammonia) and 1 per cent 

 each of phosphoric acid and potassium oxide. Sulphur and calcium 

 materials do not in the present state of our knowledge need to be 

 delimited in accordance with solubility. 



3. In either insoluble or soluble form a material to be a fertilizer 

 must not be toxic to plants even when applied in large quantities, 

 such as 1000 pounds per acre for the soluble and ten tons per acre 

 for the insoluble. This does not include sulphur, which should pref- 

 erably not be applied even in the form of flowers of sulphur at rates 

 exceeding 100 pounds per acre. 



4. A material to be a fertilizer must, in addition to the foregoing 

 qualities, possess a more or less fine or powdery consistency so as to 

 allow of facile distribution in the soil; and it must be of a nature 

 to allow free handling without danger to man or animals. 



5. An organic material to be a fertilizer must either contain the 

 quantities of the elements above indicated in either soluble or in- 

 soluble form, or must be of a nature which is readily decomposed 

 in the soil (four to eight weeks in the summer) and preferably carry- 

 ing a large bacterial population. Even organic substances contain- 

 ing 3 per cent of nitrogen, mostly insoluble in water, must be of a 

 nature to decompose readily as above indicated if they are to be 

 considered as fertilizer material. 



In accordance with these definitions, the following common sub- 

 stances can properly be regarded as fertilizers or as sources of 

 serviceable organic matter : 



NITROGENOUS MATERIALS 



Sodium nitrate Fish scrap Guano 



Ammonium sulphate Castor pomace Rat guano 



Ammonium nitrate Horn meal Slaughterhouse tankage 



Ammonium phosphate Acidulated leather Garbage tankage 



Calcium nitrate Linseed meal Meat meal 



Cyanamidc Fish meal Hoof meal 



Cottonseed meal King crab Wood and hair waste 



Dried blood Rape meal 



