256 THE POPULAR SCIENCE MONTHLY 



I lived on one field for thirty-one consecutive years, and as an average 

 of the last six years the yield was only 23 bushels per acre. Thus it re- 

 quired three years to produce 69 bushels, whereas 87 bushels are now 

 produced in one year under this system of permanent soil improvement 

 in grain farming; and even 90 bushels per acre are produced where 

 limestone and phosphorus have been used in the live-stock system, 

 which, you remember, was also suggested by Doctor Science, and which 

 we have been trying out on Field D." 



The writer also has a confession to make : 



The six-year averages of 87 bushels in grain farming and of 90 

 bushels in live-stock farming are the records of the Illinois Agricultural 

 Experiment Station for the last six years, 1904 to 1909. 



1910 Clover on the Fairfield Experiment Field in Southern Illinois. 

 Manure alone (on left) supplies but little phosphorus and will not correct the soil 

 acidity. Manure, limestone and rock phosphate (on right) produces a large yield of 

 clean clover. (If the Corn Belt needs limestone and phosphorus, what shall we say 

 of "Egypt"?) 



During the same six years the average yield of oats was as follows : 



Field A 48 bushels. 



Field B 50 bushels (with limestone applied) . 



Field C 62 bushels (with limestone and phosphorus) . 



As an average of three years during which the second crop of clover 

 was harvested for seed, 1907, 1908 and 1909, the yield of clover seed 

 was as follows : 



Field A 1.9 bushels. 



Field B 2.1 bushels (with limestone applied) . 



Field C 2.7 bushels (with limestone and phosphorus). 



As an average of the last three years, 1907, 1908 and 1909, the yield 



