82 



Elementary Principles of Agriculture 



115. Effect of Wheat and Barley Grown Continuously 

 on the Same Land. Some results from the famous ex- 

 periments of Lawes and Gilbert at the Rothamsted 

 estate* are very instructive in showing the effect of 

 growing crops continuously on the same soil. Wheat 

 and barley, as well as other crops, have been grown on 

 the same land through a series of years without manur- 

 ing. Adjoining these non-fertilized crops were others 

 treated annually with barnyard manure. Tests were 

 also made of the effect of various other fertilizers. 

 The results are given in averages for periods of eight 

 years. They show that the annual application of manure 

 increased the average annual yield twenty bushels per 

 acre for wheat and thirty-two and one-eighth bushels for 

 barley. 



EFFECT OF CONTINUOUS CROPPING WITH AND 

 WITHOUT MANURING. 



*Rothamsted Estate, Hartfordshire, England, the home of noteworthy in- 

 vestigations in agriculture under the Lawes Agricultural Trust, was founded in 

 1843 by Sir J. B. Lawes. These investigations, directed by Sir Joseph Gilbert 

 and the distinguished founder for more than half a century, have had great in- 

 fluence in shaping the agricultural practices of the world. 



