No. 4.] COMMERCIAL FERTILIZERS. 117 



it is likely to be, under average metliocls of application, quite 

 as useful as the nitrate, if not more so. In dry seasons, the 

 nitrate, being in the most useful form when applied, is likely 

 to be more serviceable than the ammonia. 



In reference to cyanamid, lime-nitrate, and the other new 

 compounds which have recently been placed upon the market 

 and whose position as yet has not been fully determined by 

 experimental work, will probably be classed with the ammo- 

 nia. The very fact that these exist in soluble forms suggests 

 a greater usefulness for them than for the inorganic forms 

 derived from ordinary supplies. 



Farmers also know that the chief sources of supply of 

 insoluble nitrogen are derived from what are called organic 

 forms, — forms which must decay before the nitrogen con- 

 tained in them can distribute itself and feed the plant. Fur- 

 thermore, because it is necessary that decay shall take place 

 before the nitrogen becomes available, the rate of availability 

 will depend very largely upon the rapidity with which the 

 substance is likely to decay. Substances that are soft, easily 

 penetrated by water and air and easily made fine by grinding, 

 or other processes, are more likely to give up their nitrogen 

 to plants than those which are hard and dense, and which 

 resist the attacks of soil solvents or other processes of decay. 

 Nevertheless, because of the characteristics which they pos- 

 sess, they play an important part in the uses that may be 

 made of commercial fertilizers containing nitrogen. Of 

 these substances, those that are the most quickly available 

 are dried blood, dried meat, cotton-seed meal, linseed meal, 

 castor pomace, meat tankage and gi'ound fish, and those which 

 are likely to decay slowly are ground bone, ground tankage, 

 ground leather and products of a similar character. It is 

 obvious, therefore, that aside from the relative availability 

 of the nitrogen contained in the two groups of nitrogenous 

 substances there is another advantage derived from a knowl- 

 edge of the sources of supply. For example, in the case of 

 nitrate of soda or sulphate of ammonia we have products 

 which are uniform, both in their composition and in their 

 rate of availabilitv, under similar conditions. In other 



