108 Report op the Chemist of the 



and, particularly, phosphoric acid, were left unused when 2,000 

 pounds of fertilizer were applied. 



Phosphoric acid is probably applied often in uselessly large 

 quantities in raising potatoes, as compared with potash and 

 nitrogen. 



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. 



INTRODUCTION. 



In 1895 several different commercial fertilizers were used in an 

 experiment which had for its object a comparison of these ferti- 

 lizers for use in raising potatoes, and especially a comparison of 

 results obtained by using different amounts of fertilizer. The 

 results were given in detail in Bulletin 93. It was found that the 

 application of 2,000 pounds of fertilizer gave in no case as eco- 

 nomical results as did the use of 1,000 pounds. 



It was further designed to raise potatoes on this same field in 

 1896, without use of additional fertilizers, in order to ascertain to 

 what extent the fertilizing materials remaining unused in the 

 soil could be utilized during the second season. The soil is pecu- 

 liarly adapted to leaching, consisting of light loam, two or three 

 feet deep, underlaid by sand and gravel and extending down in- 

 definitely. 



The field is located at Northville, L. I. The details of the 

 work were in the hands of Mr. H. L. Hallock, under the super- 

 vision of Messrs. Stewart and Sirrine, of Jamaica, as representa- 

 tives of the Station. The same methods were used in growing 

 the crop "as the preceding year. 



We will now consider in order the following points: 



(1) Yield of potatoes. 



(2) Proportion of marketable potatoes. 



(3) Relation of yield to cost of fertilizer used. 



(4) Relation of plant-food applied to that removed by crop. 

 The table below gives the detailed results secured from each 



plot with reference to yield and proportion of marketable po- 

 tatoes during the two years of the experiment. 



