CROPS AND SOIL IMPROVEMENT 



Fertilizer experiments at the various stations and 

 on farms are nearly a unit in showing that if any 

 need in plant-food exists, phosphoric acid is de- 

 ficient. When crop-producing power decreases, 

 and the farmer begins to seek a commercial fer- 

 tilizer to repair the loss, he finds that bone-dust 

 or acid phosphate is serviceable. The resulting 

 increase in yield often leads to such sole depend- 

 ence upon this fertilizer that clover and manure 

 are disregarded, the percentage of humus is al- 

 lowed to drop, and finally the fertilizer is brought 

 into disrepute. The need of phosphoric acid is 

 so common that it is the sole plant-food in much 

 fertilizer, and the dominant element in practically 

 all the remainder on the market. 



The Need of Potash. Land which is deficient 

 in organic matter ordinarily is lacking in available 

 potash, and responds with profit to applications, 

 provided the nitrogen and phosphoric-acid re- 

 quirements have been met. Clay soils contain 

 far more potash than sandy soils, and in a farm- 

 ing scheme for them that permits the use of ma- 

 nure and clover, it may not become necessary to 

 buy much potash. The liberal use of straw in the 

 stables, and the saving of all the liquid manure, 

 are helps. Farms from which the hay and straw 



[166] 



