CHAPTER VIII 



EXPEKIMENTS UPON THE CONTINUOUS GROWTH OF LEGUMINOUS 



CROPS 



I. The Continuous' Growth of Beans on the' same land, Geescroft Field. 

 II. The Continuous Growth of Red Clover on ordinary Arable Land, Hoos 



Field. 



III. The Continuous Growth of Clover on Rich Gai'den Soil. 

 References. 



I. THE CONTINUOUS GROWTH OF BEANS ON THE SAME LAND, 



GEESCROFT FIELD. 



FROM the outset of the Rothamsted Experiments repeated 

 attempts have been made to grow leguminous crops year after 

 year on the same land. The particular importance of these 

 attempts comes from the special position occupied by the 

 leguminous plants. It is well known that ordinary farming 

 experience considers that the land requires a " rest " before the 

 growth of any of these crops is repeated. Satisfactory crops 

 of clover are rarely obtained except at intervals of four years, 

 and on many soils even six or seven years must elapse before 

 the growth of clover can be renewed with any prospect of 

 success. Not only does land become "clover sick," but the 

 farmer considers it will equally become bean or pea " sick " ; 

 even lucerne, though it stands without failure for five or six 

 years or more, rarely succeeds when re-sown immediately after 

 the removal of a previous crop of the same kind. The 

 leguminous crops of course contain far greater amounts of 

 nitrogen than any others, but it is now known that the greater 

 part of this is obtained from the atmosphere, so that the 



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