36 



EXPERIMENTS UPON WHEAT 



whether the fertility of the plots has increased or diminished 

 under the treatment they receive. 



Table XVI. — Experiments on Wheat, Broadhalk Field. Average Produce 

 of Grain and Straw per acre the first 8 years (1844-1851), anc? over the 

 successive 1() -year periods (1852-1901) inclusive. 



A. Maintenance of the yield under Continuous Wheat 

 growing on the same land. 



The curves in Fig. 2 show the fluctuations in the yield of 

 total produce for the first eight-year and five ten-year periods 

 from the beginning of the experiment on certain of the plots 

 — Plot 3, which is unmanured ; Plot 2, which receives farm- 

 yard manure every year ; Plots 6 and 7, which receive a 



