ranks above the acid phosphate both as an average for the entire
period and as an average between 1895 and 1900, during which time
the land to which no phosphorus was applied produced only 55 per
cent as much as where raw phosphate was used--a result worth every
farmer's consideration.

More Bushels and Tons

The Ohio Agricultural Experiment Station has reported investigations
covering sixteen years in which raw phosphate was compared with acid
phosphate costing twice as much per acre. As an average of all
results secured, 320 pounds of raw phosphate applied with manure on
clover sod produced 8.4 bushels more corn, 4.7 bushels more wheat,
and 0.49 ton more hay per acre than where manure alone was used, and
320 pounds of acid phosphate, costing twice as much money but
containing only half as much phosphorus, applied with the same
amount of manure, produced 7.5 bushels more corn, 5.1 bushels more
wheat, and 0.46 ton more hay than where the manure alone was used.

Now I have presented the averages or summaries of all investigations
that have been reported covering ten years or more where equal money
values of raw phosphate and acid phosphate have been used, or where
any apparent provision was made to supply some organic manure,
whether as farm manure, green manure or merely as clover grown in
the rotation; and I invite the reader to mix his own brains with
these data and not to expect me to state whether he should use the
relatively cheap ground natural phosphate rock or the more costly
manufactured acidulated phosphate in the improvement of his own soil
in systems of permanent profitable agriculture.