134 ELEMENTS OF AGRICULTURE 



It seems to be very nearly as easy to double a yield of 

 one and one-half tons as to double a yield of one-half ton. 

 In the former case, the gain will be three times as much 

 as in the latter. 



The profitableness of a fertilizer is very much a matter 

 of season. In general, the best results are secured in 

 favorable seasons. A fertilizer that pays in a good season 

 may not pay in a season of deficient rainfall. 



In deciding on a fertilizer practice to be followed, one 

 should consult the State Experiment Station to learn 

 whether there are any fundamental deficiencies of the 

 soils of the region. "On practically all Ohio soils that 

 have been for any length of time in cultivation possibly 

 excepting the mucks phosphorus must be supplied be- 

 fore the maximum yield of any crop can be attained. 

 The longer the land has been in cultivation the greater 

 the need of phosphorus, but many comparatively new 

 soils will respond to it. Phosphoric acid seems to be 

 deficient in nearly all of the soils from the Appalachian 

 mountains to the Mississippi river. 



After one has obtained all the public information 

 concerning the region it is best to make trials of the most 

 likely combinations on small areas of the farm. For 

 this purpose, we should select as uniform a place in the 

 field as possible, and one that is neither better nor poorer 

 than the average. Even such trials must be accepted with 

 caution. For instance, at the Ohio Station, where trials 

 have been conducted on the same land for fourteen years, 

 the first season was abnormal ; potash gave an increase 

 in yield of wheat and phosphoric acid decreased the yield. 



, Circular No. 79 



