184 ALFALFA FARMING IN AMERICA. 
or Florida phosphatic rock, is the basis of the fer- 
tilizer called acid phosphate, or acidulated bone. It 
is made into acidulated form by the addition of 
about as much sulphuric acid as is taken of finely 
ground rock. 
The raw rock contains a large amount of phos- 
phorus, but it is not in an available condition to 
be taken up by plants; at least this is the general 
supposition. Experiment, however, shows that when 
the finely ground phosphatic rock is put in contact 
with decaying organic matter in the soil it does be- 
come available and plants feed upon it. A given 
amount of money will purchase about two or three 
times as much phosphorus in the form of raw rock 
as it will purchase in the acidulated form. 
J. F. Jack on his farm in eastern Virginia has 
given the raw rock a careful test and with very 
marked results. The rock was applied at varying 
rates, from 250 pounds per acre to 1,000 pounds per 
acre. Check strips where no fertilizer was applied 
were left. The result showed conclusively that the 
raw phosphate was available and where 1,000 
pounds per acre was applied the result was a splen- 
did growth of alfalfa. Even the application of 400 
pounds gave good results, though it is not probable 
that it would be nearly so permanent. Fully as good 
results were obtained with the raw rock on this par- 
ticular soil where a heavy growth of crimson clover 
had been turned down and about 1,000 pounds per 
acre of water-slaked lime was used, as was had from 
raw bone, 400 pounds, or acid phosphate, 400 pounds. 
