110 



EXPERIMENTS UPON ROOT-CROPS 



14 tons per acre of farmyard manure every year, but for the 

 first nineteen years of the experiment, from 1876 to 1894, 

 Plot 2 received in addition 3J cwt. per acre of superphosphate. 



Tons 

 perAcre . 

 30 



1876-94 



1895- 1902. 



20 







Series 



':?';] only. 



A C AC 



Dung and Super- 

 phosphate (I9years) 



AC 



| Dung I Dung.Superphosph 

 only. I and Potash (7 years 



ate 

 ears) 



FIG. 16. Mangolds. Effect of addition of Mineral Manure to Dung, with various 

 Nitrogenous Cross-dressings. Average Produce of Roots per acre. 



From this first period we can ascertain the effect of super- 

 phosphate as a supplement to dung. In the second period, 

 which begins in 1895, sulphate of potash has been added to 

 the superphosphate on Plots 2, so as to institute a com- 

 parison between the effect of dung alone and of dung in 

 conjunction with potash and phosphates. The results are 

 set out graphically in the accompanying diagram Fig. 16. 

 The left-hand half of this diagram shows the first period, when 

 dung is compared with dung and phosphates. The right-hand 



