224 K.BPOET ON Crop Production of the 



DISCUSSION OF RESULTS. 



The data from these experiments, which have been very fully 

 given in this and previous bulletins, bear upon three main points 

 which are important to Long Island potato growers, or those 

 producing potatoes under similar conditions: (1) The relation to 

 profit of the quantity of fertilizer applied; (2) the most desirable 

 mixture of fertilizing ingredients, with especial reference to (3) 

 the necessary amount of potash. 



THE QUANTITY OF FERTILIZER. 



For profit. — The experiments conducted by Dr. Van Slyke in 

 1895 and 1896 led to the conclusion that " the use of over 1,000 

 pounds of fertilizer an acre under the conditions tried was 

 attended with loss, as compared with the results obtained in 

 using 1,000 pounds of fertilizer." 



The results from 1897 to 1900 inclusive are summarized in the 

 following table: 



Table IX. — Increase of Yield of Potatoes from Different Quantities 



OF Fertilizer, Four Years. 



•Average of Fleet and Hallock plats. 



It is very evident that the increase in yield is not proportional 

 to the quantity of fertilizer applied. As an average for four 

 years, the first 500 lbs. caused an increased yield of 23.3 bushels; 

 the second 500 lbs., 21.9 bushels; the third 500 lbs., 11.2 bushels; 

 and the fourth 500 lbs., 6 bushels. The fertilizer (L. I. Formulas) 

 cost about $25.00 per ton. If we assume that the potatoes were 

 worth 50 cents per bushel we have the balances as shown below. 



