PENNSYLVANIA FIELD EXPERIMENTS 



429 



TABLE 80. PENNSYLVANIA EXPERIMENTS : FOUR-YEAR ROTATION 

 Records per Acre for Three Complete Rotations, 1897 to 1908 



12-year period. Of course, the actual decrease will grow less and 

 less as soil depletion continues, even though the per cent of decrease 

 remain constant, for, as already stated, it is as impossible to com- 

 pletely exhaust a soil as it would be to exhaust a bank account 

 under a contract that only 2 per cent of the remaining deposit 



