III. COMMEHCIAL FERTILIZERS FOR 



POTATOES.* 



W. H. JORDAN. 



SUMMARY. 



In experiments on four farms including eight acres of land and 

 eighty plats, the production of potatoes from the application of 

 500 pounds, 1,000 pounds, 1,500 pounds, and 2,000 pounds of com- 

 mercial fertilizer per acre was ascertained. 



(1) The use of 1,000 pounds of fertilizer per acre gave the 

 greatest profit. The slightly larger jield caused by increasing 

 this application to 1,500 or 2,000 pounds, cost in fertilizer ex- 

 pense considerably more than the market value of the potatoes. 



(2) The fertilizer cost of the increased yield of potatoes where 

 500 or 1,000 pounds of fertilizer was used per acre was 20 cents 

 per bushel in those experiments that proceeded without unfortu- 

 nate conditions. 



(3) The yield of tubers from the L. I. formula was somewhat 

 larger than from a formula compounded with reference to the 

 composition of the potato plant. 



(4) The evidence obtained in these experiments concerning the 

 relative effect of the muriate and the sulphate of potash upon 

 the composition of the potato tuber is inconclusive. 



(5) The proportions of the valuable plant-food compounds 

 found in the potato tubers were not influenced appreciably by 

 the amount or kind of fertilizer used. 



INTRODUCTION. 



The economical purchase and use of commercial plant food is 

 at present one of the very complex problems of Agriculiure. 

 This is especially the case where intensive methods of culture are 

 followed and where the larger part of the materials needed for 

 the production of crops must be obtained from some source out- 

 side the soil. 



•Reprint of Bulletin No. 137. 



