296 SYSTEMS OF PERMANENT AGRICULTURE 



In Scott County, Indiana, an experiment to determine the relative value of 

 raw rock phosphate and acid phosphate was started in 1904 and continued for 

 four years. Equal values of rock phosphate and acid phosphate were ap- 

 plied in ONE application the first year corn and wheat alternating. The 

 actual amount of plant food applied was 286 pounds of total phosphoric acid 

 in the rock phosphate and 100 pounds phosphoric acid in the acid phosphate. 

 There were three plots in the experiment one fertilized with rock phosphate, 

 one with acid phosphate, one unfertilized. Notwithstanding the fact that the 

 first year's corn crop was a total failure on all plots, the results on wheat showed 

 a gain of fourteen bushels per acre with acid phosphate as against only nine 

 bushels for the rock phosphate over the unfertilized plot. The profit per acre 

 in four years from rock phosphate was $11.55; ' the profit in four years from 

 acid phosphate was $13.50. 



In Marion County, Indiana, another experiment for the same purpose was 

 started, and crops harvested for two years. 2 Only one application of fertilizer 

 was made, the entire amount being applied the first season. As in Scott County, 

 equal values of rock phosphate and acid phosphate were applied. The results 

 speak for themselves, and they are given in the table below as taken from 

 Circular No. 10 of the Indiana Experiment Station. The yields are given in 

 bushels per acre: 



CORN WHEAT 



Amount per acre 1904 1905 



Unfertilized 20 3 



Rock phosphate, 1000 Ib 20 6 



Acid phosphate, 715 Ib ._ 27 16 



The value of the increase per acre, figuring corn at 35 cents 

 and wheat at 80 cents per bushel, on the plot fertilized with 



acid phosphate, was $12.85 



Deducting cost of acid phosphate 5.00 



Net return on the increase $7.85 



Value of the increase with rock phosphate 2.40 



Deducting cost of rock phosphate 5.00 



Or a net loss of $ 2- 6o per acre 



On the total yields the results were as follows: 



Unfertilized . ^.40 per acre 



Raw rock phosphate 6.80 per acre 



8 Acid phosphate I7 . 25 per acre 



: This is a very fair profit considering that about two thirds of the raw rock 

 phosphate will remain in the soil after the acid phosphate is completely exhausted, 

 .t should also be noted that the cost of the acid phosphate was figured at $14 per 

 ton, and the cost of the raw phosphate at $10 per ton. C. G H 



3 Italics mine. C. G. H. 



8 Cost of rock phosphate and acid phosphate deducted. 



