50 " " 5c 2.50
----- ------
Totals 167.7 $15.00
Add average charge for mixing, etc. 8.00
------
$23.00

The selling price of this would very likely be not less than $25.

This seems at first sight to be cheaper and more reasonable. But let
us see.

In a ton of mixture A he gets 335.4 pounds of plant food for $40, or
at an average cost of twelve cents per pound, while in a ton of
mixture B he gets 167.7 pounds of plant food for $25, or at an average
cost of fifteen cents per pound.

To put it another way, in a ton of the high grade mixture A, he gets
335.4 pounds of plant food for $40. To get the same amount of plant
food, 335.4 pounds, in the low grade mixture, B, it will be necessary
to buy two tons at a cost of $50.

A low grade fertilizer is always expensive even if the plant food is
furnished by high grade materials.

BUY ON THE PLANT FOOD BASIS

The farmer generally buys his fertilizer on the ton basis. A better
method is to buy just as the fertilizer manufacturers buy the raw
materials they use for mixing, namely, on the basis of actual plant
food in the fertilizer. The dealers have what they call the "unit
basis," a "unit" meaning one per cent. of a ton or twenty pounds of
plant food. A ton of nitrate of soda, for instance, contains 310
pounds or 151/2 units of nitrogen, which at $3.20 cents per unit would
cost $49. Buy your mixture of a reliable firm, find out the actual
amounts of the plant foods in the mixture and pay a fair market price
for them.

CHAPTER XXIII

COMMERCIAL FERTILIZERS--CONCLUDED

THE HOME MIXING OF FERTILIZERS

When a considerable amount of fertilizer is used a better plan than
buying mixed fertilizer is to buy the raw materials and mix them
yourself. For example, a farmer is about to plant five acres of
cabbages for the market. He finds that a certain successful cabbage
grower recommends the use of fifty pounds nitrogen, fifty pounds
phosphoric acid and seventy pounds potash per acre. For the five acres
this will mean 250 pounds nitrogen, 250 pounds phosphoric acid and 350
pounds potash. To furnish the nitrogen he can buy 1,613 pounds of
nitrate of soda or 2,500 pounds dried blood or 1,250 pounds sulphate
of ammonia, or a part of e