78 



EXPERIMENTS UPON BAELEY 



this case is very high, being estimated at nearly five times as 

 much as on any of the other plots. 



One of the permanent barley plots (Plot 7) received 14 tons 

 of farmyard manure per acre each year for tv^^enty years in 

 succession, viz., from 1852 to 1871. It was then divided into 

 two plots, one of which, 7-1, has received no manure of any 

 kind since ; the other, 7-2, continued to get its annual dressing 

 of 14 tons of dung. After the discontinuance of the dung, the 

 barley crop on that half of the plot naturally began to fall off", 

 but only slowly, and even now, after thirty years' cropping 

 without manure, the effect of the residues left by the previous 

 twenty years' application of dung is still to be seen in a 

 yield that is double the crop obtained from the continuously 

 unmanured plot. Table XXXII. shows the total produce 



Table XXXII. — Total Produce per acre of Barley Plots, shovjin;/ Prsid/a'l 

 affects of Dung. 



obtained from the three plots in question for the thirty years 

 tvhich have elapsed since the dung on Plot 7-1 was discontinued, 

 the first five years are given singly, after that five years are 

 grouped into one period and the mean result given. In order 



