COMPUTATION OF FERTILIZER MIXTURES 3 
If it is desired to supply a fertilizer constituent, such as ammonia, 
from two or more single constituent materials, it is customary to 
decide arbitrarily beforehand on the percentage of the constituent 
in the fertilizer which shall be supplied by each material. The 
quantity of each material to be taken is then found directly in the 
usual way by reference to Table 1. 
When one or more of the materials used in a fertilizer contains 
more than one fertilizer constituent, the calculation of the mixture 
can most conveniently be done by listing the data in tabular form, as 
illustrated in Table 2. Of the materials listed in the table for use in a 
3-8-3 mixture, three contain ammonia. If it is decided that the 
sodium nitrate shall supply half of the ammonia (or 30 pounds per 
ton of fertilizer) and the cottonseed meal and tankage 15 pounds each, 
then the weights of these materials required to yield these quantities 
of ammonia are 162, 200, and 177 pounds, respectively. But 200 
pounds of cottonseed meal also contain 5.6 pounds of P 2 5 and 
3.4 pounds of K 2 0, while 177 pounds of tankage contain 8.8 pounds 
of P 2 5 . The remaining 145.6 pounds of P 2 5 and 56.6 pounds of K 2 
require, respectively, 910 pounds of acid phosphate and 283 pounds 
manure salt. 
Table 5 
!. — Method of listing data for 3 
-8-3 fertilizer mknture 
Materials 
Composition 
Constituents required 
Material 
NH 3 
P2O5 
K2O 
NH 3 
P2O5 
KO2 
required 
Nitrate of soda. . 
Per cent 
18.5 
7.5 
8.5 
Per cent 
Per cent 
Pounds 
30.0 
15.0 
15.0 
Pounds 
Pounds 
Pounds 
162 
2.8 
5.0 
16.0 
1.7 
5.6 
8.8 
145.6 
3.4 
200 
177 
910 
20.0 
56.6 
283 
Total 
60.0 
160.0 
60.0 
1 732 
Filler 
268 
2,000 
The general formula for the calculation of a fertilizer mixture of 
this kind may be expressed as follows: 
If a = Percentage of NH 3 
a' = Percentage of NH 3 
a' ' = Percentage of NH 3 
b — Percentage of P 2 5 
b' = Percentage of P 2 3 
6"= Percentage of P 2 5 
c = Percentage of K 9 
in sodium nitrate 
in cottonseed meal 
in tankage 
in cottonseed meal 
in tankage 
in acid phosphate 
in cottonseed meal 
c' = Percentage of K 2 in manure salt 
then for an A-B-C fertilizer 
X, sodium nitrate required = 2, 000 
A/2 
X' ', cottonseed meal required =2, 000 
A/ 4: 
X" , tankage required = 2, 000 
A/4 
a' 
Y, acid phosphate required 
a 
2,000 B 
Q>X' + V X") 
Z, manure salt required = 
2,000 C-cX' 
