54 Fertilizers 



its extreme solubility makes it possible, when moisture 

 conditions are good, to reach every portion of the soil in 

 which the roots are located, so that it is not only more 

 available by virtue of its being in the right form, but 

 because it readily goes to the place where the plant 

 roots are. The next substance in order of availability 

 is ammonia, and the rapidity with which ammonia 

 will change to a nitrate makes it under many 

 circumstances quite as useful. It possesses, also, one 

 great advantage possessed by the nitrate, that of being 

 soluble in water, and thus readily distributes itself through- 

 out the surface soil. The difference in usefulness of 

 these two forms seems to depend more largely upon the 

 character of the season than upon the exact form. In a 

 very wet season the nitrate is less useful, because liable 

 to be washed below the reach of the roots, or lost alto- 

 gether, and in a dry season it is more useful than the 

 ammonia, because as soon as it is in solution it is capable 

 of being absorbed. It must be remembered, however, 

 that these two forms possess the further advantage over 

 organic forms, that they are definite chemical compounds, 

 which always possess the same characteristics, and under 

 similar conditions they always act in the same way. If 

 nitrogen is purchased as ammonia, the source of the 

 nitrogen is not important ; that is, whether derived from 

 the manufacture of illuminating gas, coke, or bone- 

 black, or from one of the newer ammonia compounds, if 

 it is ammonia, it is identical in character. The same is 

 true of nitrate the original source of the nitrogen is 

 immaterial. 



The availability of nitrogen in organic forms, as already 

 pointed out, depends upon the rapidity with which they 

 will change to the nitrate under varying conditions. 



