2 86 SYSTEMS OF PERMANENT AGRICULTURE 



on the investment in the first three years, and during the next two 

 years it paid the annual cost and 40 per cent net profit on the same. 



The results of the Galesburg field are in harmony with those thus 

 far secured from many other University of Illinois soil experiment 

 fields in different parts of the state, and they are also in harmony 

 with numerous practical tests by progressive Illinois farmers who 

 make adequate provision for supplying the soil with decaying 

 organic matter. Thus, as an average of four independent tests on 

 each experiment field, Tennessee raw rock phosphate increased the 

 yield of corn in 1908 by 12.1 bushels per acre on the Galesburg 

 field, by 11.9 bushels on the Myrtle field for first-year corn and 9.3 

 bushels for second-year corn, by 16.0 bushels on the Rockford 

 field for first-year corn and 7.6 bushels for second-year corn, by 

 3.5 bushels on the Antioch field, by 9.1 on the Auburn field, and 

 by 8.4 bushels on the Urbana field. 



These experiment fields are in six different counties, and they 

 have been in operation from four to six years. The average yield 

 of corn in 1908 was 67.3 bushels where raw phosphate has been 

 applied and 57.5 bushels without phosphorus. The phosphate 

 applied thus far adds phosphorus to the soil at the rate of 60 pounds 

 or more per year, while 16 pounds are required for a 68-bushel crop 

 and about 2 pounds for the lo-bushel increase. Thus, the value 

 of the increase ($3.43) will pay the cost of the phosphate (less 

 than $2) and leave 50 per cent net profit, and with 70 per cent of 

 the phosphorus left in the soil. 



The effect on wheat and clover is almost as marked as on corn. 

 Of course, more clover means more nitrogen secured from the air, 

 and it may also mean more manure to return to the soil. Mean- 

 while, the untreated land grows poorer year by year. 



In Table 51 are given the results reported by the Illinois Experi- 

 ment Station (Circular 97) from a series of pot cultures conducted 

 for the purpose of comparing equal money values of raw rock phos- 

 phate and steamed bone meal. In the Illinois field experiments, 

 the standard annual application of phosphorus is 25 pounds per 

 acre in 200 pounds of steamed bone meal and nearly equal money 

 values of other forms of phosphorus. The 25 pounds is based upon 

 the requirements of a zoo-bushel crop of corn, with i or 2 pounds 

 for loss in drainage. In pot cultures very large crops are commonly 



