WILD VEGETATION AFTEE WHEAT, ETC. 137 



another leguminous crop, after it had become " sick " through 

 the long-continued growth of beans ; there is ottyer evidence, 

 however, that the growth of one leguminous crop renders the 

 soil less fitted to carry another, even of a different species. 



TABLE XLIX. 



* Barley and Clover together. 



After the removal of the clover crops in 1885 this portion 

 of the field was fenced off to exclude cattle, and has been left 

 uncultivated ever since. A luxuriant growth of grasses and 

 other vegetation soon established itself, which may be profit- 

 ably compared with the similar natural vegetation that has 

 established itself after the wheat at the top of Broadbalk field 

 (see p. 41). In the summer of 1903 a portion of the herbage 

 was cut on both these portions of land which had been allowed 

 to run wild after wheat and leguminous plants respectively ; 

 these were sampled as usual and a full botanical analysis 

 made, the results of which are set out in Table L. Early 

 in 1904 soil samples were also obtained from three places 

 in each field, and determinations of carbon and nitrogen 

 have been made to compare with those made at the beginning 

 of the experiments, so as to ascertain the accumulation of 

 fertility by the land left under "prairie" conditions for twenty 

 years. 



It will be observed that the leguminous plants had never 

 been able to obtain a footing in the Geescroft field after clover 

 and beans, although in the similar wilderness following wheat 

 in the Broadbalk field, Lathyrus constituted a considerable 

 proportion of the herbage. The conclusion seems inevitable 

 that the preliminary long-continued growth of leguminous 



