198 DR. DAUBENY ON THE ROTATION OF CROPS, ETC. 



The following represents the curve of their growth : — 



Beans. 



Years. 



A , 



10 



60 



50 



40 

 Pennanent 



30 



Shifting 



20 



10 



60" 



50 



40 



30 



20 



10 



>"lbs 



1 2 3 45678910 



In the contiguous manured bed the crop was only 27' I lbs., not greatly exceeding 

 the average of the permanent, and falling considerably short of that of the shifting 

 crops. 



7. Nicotiana rustica. 



Tobacco is one of the plants which most strikingly illustrates the dependence of the 

 crop upon manuring; the first year the produce being 178 lbs., whilst it sunk in six 

 years' time to 17 lbs. The whole of this diminution, however, must not be set down 

 to the deficiency of inorganic matter, since in subsequent years the produce became 

 greater, although it never recovered its former rate. 



In this instance the permanent presents a higher average than the shifting crop, 

 but this seems attributable to the circumstance that in the latter instance the soil had 

 been previously drawn upon by a crop of beans, whilst in the former it had been 

 recently manured. 



The following are the results : — 



