6 BULLETIN 102, PART 2, UNITED STATES NATIONAL MUSEUM. 
existing conditions at least, must be counted upon to carry fertilizer 
utilization to its proper realization. 
By long experience, it has been found that those elements of which 
the soil is most quickly depleted are nitrogen, phosphorus, and po- 
tassium; and therefore compounds of these elements are the chief 
ingredients of the commercial fertilizers. Calcium, in the form of 
lime or crushed limestone, is added with favorable results to some 
soils; but this is more to counteract or neutralize a high acidity or 
“ sourness ” than to contribute a needed constituent , 1 and since, 
moreover, limestone is so widely distributed that an organized in- 
dustry is not necessary to supply it, this substance will not be con- 
sidered in further detail in this paper. Sulphur, in the elemental 
condition, has recently come to the front as a fertilizing material of 
some promise, but its use, as well as that of sulphuric acid on the alkali 
lands of the West, may be said to be still in an experimental stage. 
The fertilizer industry, therefore, as it exists at present, is concerned 
with the preparation of suitable compounds of nitrogen, phosphorus, 
and potash to form commercial fertilizers, which are distributed for 
immediate addition to the soil. The securing of an adequate supply 
of raw materials, and the development of a wider and more intelli- 
gent use of fertilizers, are two problems of the utmost importance, 
especially at the present moment, when the World War endangers 
certain of the supplies and at the same time necessitates an increased 
yield in food. 
The chart accompanying this paper is designed to present in 
graphic form, in a single expanse, the normal fertilizer situation in 
the United States and the significant effects that the present war has 
exerted upon this situation. It will serve to set forth in their true 
proportions the relative importance of the many sources of supply, 
both domestic, foreign, and potential, that go to make up the manu- 
factured product ; and to remove the disproportionate weight that has 
attached to some of them as a result of undue publicity. 
THE RAW MATERIALS OF FERTILIZERS. 
Phosphorus. 
Phosphorus, in the elemental condition, is a very active substance, 
but in the form of compounds present in the soil it loses its vigor 
and enters quietly into the structure of plants and through them 
into animals. In the former it is found in largest quantity in the 
seed and fruit; while in the latter it is an important constituent of 
1 In some soils, lime and limestone set up chemical reactions which render 
the potash and phosphorus more available, and also facilitate the growth of 
nitrogen-fixing bacteria; so that in such instances these materials have an in- 
direct fertilizing value. 
