SOIL SESSION. 



127- 



of getting more plant food out of the soil, and so running out the faster 

 the supply of the limiting plant- food element. Where we have fol- 

 lowed the three-year rotation and have added lime to give us better 

 clover, corn has yielded seventy-eight bushels; the soil is not sour to any 

 marked degree. On the next plot to which steamed bone meal has been, 

 applied, the yield gave but two bushels more. Both of these applica- 

 tions have cost annually seven bushels of 35 cent corn. In the case of 

 the phosphorus plot, we have paid for the treatment, and have four 

 bushels of corn clear profit. The important thing here, however, is not 

 this profit for this year or for next year, but it is that the two-hundred:: 

 pounds of steamed bone meal applied carried phosphorus enough to • 

 grow ICO bushels of corn, and we have taken off but eighty-nine. 



Plate 2.— Clover after Oats with Lime Treatment. 



Under this system, not only is the supply of the limiting element 

 phosphorus being increased, thereby building up the soil, but at the same 

 time an actual profit is being returned. The fact is, there is nearly al- 

 ways profit in a system of soil management whereby the productive ca- 

 pacity is gradually and permanently increased. On the other hand, there 

 is ultimate loss in a system which destroys the productive power of a 

 soil, a system on account of which the yield gradually becomes smaller. 



On this same soil, on June 7, 1905, five plots, without phosphorus, 

 yielded on the average one and one-quarter tons of field-cured clover 

 hay, while five plots, to which phosphorus had been applied, averaged at-. 



