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. 



