28 POTATO CULTURE. 



the manufacturers would not send me a poor article. I will 

 tell you of one experiment. 



S. C. rock phosphate, pure ground bone, and Mapes potato- 

 manure (a so-called complete manure for potatoes) were 

 used. Muck had been applied to the land, which contained 

 much nitrogen, and potash was abundant naturally, and so 

 in theory the rock phosphate was just what I wanted. The 

 complete manure, containing every ingredient necessary for 

 the growth of a crop, was certainly all right, but it might 

 cost too much, as some of the ingredients, might not be 

 needed. Experiments were made in three different lots, on 

 strips 50 to 60 rods long, using at the rate of 600 to 1000 

 pounds per acre. Great care was used in the measuring, 

 weighing, etc., that the experiments might be accurate. I 

 will not take space to give full details, but will simply say 

 that, much to my surprise, no benefit was derived from any 

 of them. There were slight variations in yield, but no great- 

 er than could be accounted for by the natural variations of 

 the soils. It was a wet season. The next year was quite 

 dry, and the same ground was in potatoes again, but no 

 difference in growth or yield could be seen on these plats. 



The experimental rows in one case ran across a piece of 

 rather poor land, where the yield was much below the aver- 

 age. Here, I thought, surely I should see good results, but 

 was disappointed. Rotten stable manure will increase the 

 yield every time, even when the land is already quite rich ; 

 now, why will not a complete manure, containing all the 

 ingredients of stable manure, do the same ? Why did it not 

 show some effect on poor land ? Rotten manure would have 

 done so. That same season, by the use of stable manure, 

 freely applied, a half-acre was made to yield more than 200 

 bushels. 



In spite of these experiments, when a circular came one 

 spring, with a picture of a fine large potato (450 bushels per 

 acre) grown with the potato-manure, and a little scabby one 

 (120 bushels per acre) grown with animal manure, I could 



