COMPUTATION OF FERTILIZER MIXTURES 7 
ferences recently held at Chicago, Boston, Baltimore, Shreveport, 
and Atlanta, attended by agronomists of various States and repre- 
sentatives of manufacturers selling fertilizers in the States mentioned 
on p. 12. At these conferences, 52 analysis formulae 4 were recom- 
mended, varying from 14 to 32 per cent in plant food constituents, 
with an average of 18 per cent. These recommendations, if put into 
practice, would increase the concentration of fertilizers about 51 per 
cent over the average mixed fertilizer of a few years ago. 
In addition to the cost of handling and transporting, there still 
remains a more serious objection to dependence on low-grade material 
for future expansion in fertilizer manufacture. This is the question of 
supply. A number of materials, as cottonseed meal, tankage, etc., 
which have been used extensively in fertilizers, are being used more 
ancLmore as feed for livestock. The output of these industrial by- 
products is limited by the production of the principal products and 
can not be increased independently of the latter to meet an increased 
demand for the by-product. 
To meet the probable future needs for nitrogenous materials, atten- 
tion is now being directed to a source that is neither mineral deposit 
nor industrial by-product — namely, the nitrogen cf the air. 
When atmospheric nitrogen is fixed as ammonia, nitrogen is obtained 
in one of its most concentrated combinations. Ammonia, as such, 
however, can not be used directly as a commerical fertilizer; it becomes 
suited for this purpose only when neutralized with an acid. 
Investigations by the Bureau of Soils, 5 now commercially utilized, 
have shown the feasibility of the industrial production of phosphoric 
acid by volatilization from phosphate rock, and the probable direct 
competition of this procedure with the sulphuric acid method for the 
treatment of phosphate rock. From the fertilizer standpoint, the 
newer method has the advantage of directly yielding an acid of a 
concentration most suitable for combining with ammonia, and for 
making, by substitution for sulphuric acid, many other concentrated 
materials such as the phosphates of sodium and potassium. 
The manufacture of fixed nitrogen and of phosphoric acid thus 
provides the means for making many high-analysis fertilizer materials 
which may have wide application in the future if the supply of low- 
grade material falls short of the demand. 
CONCENTRATED FERTILIZER COMPOUNDS 
In Table 3 are given the chemical and physical properties of a 
number of inorganic materials which contain one or more of the 
essential constituents of fertilizers. The incompleteness of the table 
is due to the fragmentary nature of the data recorded in the litera- 
ture, which, in addition, are often very conflicting. Some of the 
materials listed are now widely used in fertilizers. The data for the' 
others are supplied for the purpose of showing which materials may 
have future application in increasing the concentration of fertilizers 
and which have properties that prevent their use for this purpose 
unless a satisfactory way is found to eliminate the properties that 
are considered objectionable. 
4 The Standard Analyses. Anon. Am. Fertilizer, vol. 58, No. 4, p. 27, 1923; High Analysis. Anon. 
Am. Fertilizer, vol. 59, No. 9, p. 28, 1923. 
5 The Use of the Cottrell Precipitator in Recovering the Phosphoric Acid Evolved in the Volatilization 
Method of Treating Phosphate Rock. W. H. Ross, J. N. Carothers, and A. R. Merz. J. Ind. Chem., 
vol. 9, p. 26-31, 1917; Electric Furnace Smelting of Phosphate Rock and Use of the Cottrell Precipitator in 
Collecting the Volatilized Phosphoric Acid. J. N. Carothers, J. Ind. Eng. Chem., vol. 10, p. 3.5-8, 1918; 
Investigations of the Manufacture of Phosphoric Acid by the Volatilization Process. W. H. Waggaman, 
H.W. Easterwood, and T. B. Turley. U. S. D. A. Dept. Bull. 1179, p. 1-53, 1923. 
