( 6i cwt. 

 .4 dl " 



( 2i " 



MANLKES FOE POTATOES. 263 



Bushels per acre. 

 superphosphate .................... ) 



muriate ot potash .................. [-321 



sulphate of ammonia .............. ) 



j 6i cwt. superphosphate .................... (_ 90 



1 2* " sulphate 01 ammonia ............. J 



3. No manure ......................... -. ...... 252 



4 ( 6? cwt. superphosphate .................... ) 01 -. 



*'|-84 " muriate of potash ................. J 



5. 2i cwt. sulphate ot ammonia .............. 238 



6. 15 tons farin-yaid manure .................. 365 



" It is curious," said the Doctor, " that the plot with sulphate of 

 ammonia alone should produce less than the no-manure plot." 



"The sulphate of ammonia," said I, "may have injured the 

 seed, or it may have produced too luxuriant a growth of vine." 



Another series of experiments was made on another portion of 

 the same field in 1871. The "no-manure" plot produced 337 

 bushels per acre. Manures of various kinds were used, but the 

 largest yield, 351 bushels per acre, was from superphosphate and 

 sulphate of ammonia; fourteen tons barn-yard manure prod ce 

 340 buslicls per acre; and Mr. Hunter remarks: "It is evident 

 that, when the produce of the unmanured soil reaches nine tons 

 [336 bushels] per acre, there is but little scope for manure of any 

 kind." 



"I do not see," said the Doctor, " that you have answered my 

 question, but I suppose that, with potatoes at fifty cents a bushel, 

 and wheat at $1.50 per bushel, artificial manures can be more 

 profitably used on potatoes than on wbeat, and the same is prob- 

 ably true of oats, barley, corn, etc." 



I have long been of the opinion that artificial manures csn be 

 applied to potatoes with more profit than to any other ordinary 

 farm-crop, for the simple reason that, in this country, potatoes, on 

 the average, command relatively high prices. 



For instance, if average land, without manure, will produce fif- 

 teen bushels of wheat per acre and 100 bushels of potatoes, and a 

 given quantity of manure costing, say $25, will double the crop, 

 we have, in the one case, an increase of: 



15 bushels of wheat at $1.50 ................ $22.50 



15 cwt. of straw ............................ . 3.50 



$26.00 

 Cost of manure ......................... . 25.00 



Profit from uing manure ................... 7 61.00 



And in the o'her: 



100 bushels of potatoes at SO cents ...... . ..... ?50.00 



Cost of manure ............................. 25.00 



Profit from using manure ................ $25.00 



