254 SYSTEMS OF PERMANENT AGRICULTURE 



TABLE 396. OHIO EXPERIMENTS WITH MANURE, RAW ROCK PHOSPHATE, 

 AND ACID PHOSPHATE Continued 



CLOVER HAY, TONS PER ACRE 



TOTAL VALUE OF THE THREE CROPS PER ACRE 



It is worth while to note that the first corn crop on Series C 

 (Table 39) was not benefited by raw phosphate, and the first corn 

 crop on Series B (Table 38) was increased only 2.7 bushels, as an 

 average, by raw phosphate, while other instances appear in which 

 phosphorus produced no apparent benefit, as, for example, with 

 stall manure for corn in 1901 and 1906, and with either manure 

 for wheat in 1907, all of which emphasizes the fact that one field 

 trial with one crop for one year may have almost no value in de- 

 termining the effect of additions of phosphorus to the soil. 



Director Thorne has expressed some disappointment l because 



1 Considering its source, the following statement by Director Thorne, taken by 

 itself, probably constitutes the strongest "evidence" that can be quoted in favor 

 of acid phosphate and against the use of raw rock phosphate. In referring to the 

 general averages of all results secured in these manure-phosphate experiments 

 from 1897 to 1907, he says (Ohio Agricultural Experiment Station Circular 83, 

 page 23) : 



''While the treatment of manure has in every case increased its effectiveness, the 

 gain per acre produced by reenforcing the manure with acid phosphate has been so 

 much greater than that from any other treatment that it has not been profitable 

 to use anything else, even though the other materials had cost nothing. " 



Of course, in this statement, Director Thorne refers not to profit on investment, 

 but to profit per acre regardless of the amount invested, and he includes the data 



