600 Keport of the Department of Field Crops of the 

 The Questions Asked of the Experiment. 



The main object of this experiment is to get information in 

 regard to the profitable quantity of fertilizer to be used, but there 

 are certain incidental problems which may be studied in connec- 

 tion with the main one without diverting the work from its chief 

 purpose. 



Three questions are asked, therefore: 



(1) What is the profitable amount of commercial fertilizer to 

 apply in potato growing? 



(2) Shall we apply plant food in the proportions used by the 

 potato plant or in some other? 



(3) Is the sulphate of potash preferable to the muriate for use 

 in growing potatoes? 



The Fertilizers Used. 



The purposes of this experiment require the use of four differ- 

 ent mixtures of fertilizing materials, the ingredients and actual 

 composition of which are given below. 



Formula No. 1. — This formula is supposed to contain plant 

 food in nearly the proportions used by the entire potato plant 

 excepting that the phosphoric acid is in considerable excess; and 

 was mixed as follows: 



Potato Formula A. 

 Ingredients. Composition. 



Nitrate of soda 192 pounds. Nitrogen 6.6 percent. 



High grade dried blood SOO pounds. Available phos. acid 4.75 per cent. 



Acid phosphate 570 pounds. Potash 10.31 percent. 



Muriate of potash 400 pounds. 



Land plaster 38 pounds. 



2000 pounds. 



Formula No. 2. — This formula was intended to contain the 

 same percentages of the three ingredients as Formula No. 1, the 

 only difference being that the potash is supplied as the sulphate 

 instead of the mutriate. 



