]SIew York Agricultural Experiment Station. 220 



In 1898, the first year, when the yield of potatoes was fairly 

 large, the entire absence of potash from the fertilizer was with- 

 out iuiiuence on any one of the four farms. Forty pounds of 

 nitrogen and eighty pounds of phosphoric acid per acre without 

 potash caused! as large an increase of tubers as when accompanied 

 by one hundred poundis of potash. In the two succeeding years, 

 while the erops were small on all plats, potash either in small or 

 large proportions had little effect. It must be conceded that up 

 to the point to which these experiments have been carried, nitro- 

 gen and phosphoric acid, one or both, were the ingredients upon 

 which dependence could be placed as a source of profit. 



Experimental results no more extensive than those herewith 

 reported should not be taken as justifying the exclusion of potash 

 from commercial fertilizers. This is in any case a local question. 

 There are good reasons for inquiring, however, whether, consider- 

 ing the capacity of our soils and in view of considerable experi- 

 mental data, the importance of potash salts has not been some- 

 what overestimated by Long Island potato growers. 



PRACTICAL LESSONS TAUGHT BY THESE 

 EXPERIMENTS. 



It seems to the writer that practical lessons of great value may 

 be drawn from the results of these experiments. In the first 

 place, it is clearly shown that the use of very large quantities of 

 commercial plant food is attended with great financial risk unless 

 all conditions of soil and season are favorable. But even when 

 the best conditions prevail, the largest crop which may be secured 

 by a very liberal application of fertilizers is not necessarily the 

 most profitable. The money balance from a medium crop may 

 often be larger than fro^m a maximum yield for the reason that 

 the fertilizer cost per unit of production increases very rapidly 

 after the production passes a certain point. It is only with very 

 high priced crops that excessive feeding is justifiable from the 

 standpoint of good business management. 



Again, it is well worth much time and careful observation to 

 discover the needs of a soil upon which commercial fertilizers are 



