BARNYARD MANURE 



137 



years on land unmanured, manured continuously, and 

 manured during the first twenty years only, showed a 

 gradual decrease in the crop on the unmanured soil and a 

 gradual increase from year to year on the manured soil. 

 When the application was stopped there was a gradual 



Pounds of grain per acre 

 6,000 



5,000 



4,000 



3,000 



2,000 



1,000 



1852- 1871 1872-1881 1882-1891 1892-1901 



Fir,. 59. Effect* of barnyard manure on the yield of barley ten-year averages. 

 ^H Manured every year. 



2- Manured every year until 1871, but no manure since that date. 

 === No manure since 1852. 



Thirty years after the last application of manure to the second plot it still 

 Kave a ten-year average yield double that of the unmanured. 



decrease, but, at the end of thirty years after the last 

 application, the yield was still double that on the unma- 

 nured part. 1 (See Fig. 59.) 



1 The Book of the Rothamstccl Experiments, by A. I). Hall, p. 7S 



