AVEEAGE YIELD OF POTATOES 



123 



Abundance," five years; "Bruce," one year; and "White 

 Beauty of Hebron," 1897-1901. The question was not as to 

 the comparative merits of different varieties, but different 

 sorts were selected on the supposition that in growing the crop 

 year after year a change was desirable, especially with a view 

 to the avoidance or lessening of disease. The special object 

 was to ascertain the manurial requirements of the crop and 

 the comparative character and composition of the produce. 

 Table XLV. gives the details of the manuring and the 

 average produce for the whole period of twenty-six years. 



TABLE XLV. Potatoes, average yield per acre over 26 years 

 (1876-1901). 



* Applied in the first 6 years only (1876-81). 



t 8-5 cwt. Superphosphate also in the first 7 years (1876-82). 



J 550 Ib. Nitrate of Soda also in the first 6 years (1876-81). 



The crop was grown continuously without manure, with 

 various artificial manures, and also with farmyard manure, both 

 alone and with some artificial manures. There were ten 

 differently manured plots, and under each of the ten conditions 

 the crop more or less declined over the later compared with the 

 earlier years. The average produce per acre of total tubers 

 over the twenty-six years was without manure, only 27*4 

 cwt. ; with ammonium-salts alone, 34'0 cwt. ; with nitrate of 

 soda alone, 42'5 cwt. ; with superphosphate alone, 54'4 cwt. ; 



