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VIII. On the Exhaustion of Soils. By Edward Solly, Esq., 

 F. R. S., F. L. S. t Hon. Memb. Roy. Agr. Soc. Eng. Experi- 

 mental Chemist to the Horticultural Society. 



(Communicated by the Chemical Committee.) 



Although it is well known that some plants take more from the 

 soil than others do, some requiring a large quantity of inorganic 

 matters, such as Alkalies and the earthy Phosphates, whilst 

 other plants require a comparatively small quantity, and hence in 

 growing do not exhaust or impoverish the soil to so great an 

 extent ; yet there are many points connected with the subject, and 

 having immediate reference to practical operations, which are by 

 no means so clear as could be wished. The following observa- 

 tions relate to one of these questions in particular, viz. what is the 

 maximum and minimum of exhaustion, for any given plant. In a 

 previous paper it has been shown, that the same plant grown in 

 the same soil but differently manured, exposed to the influence 

 of particular substances, or placed under different conditions, con- 

 tains variable proportions of inorganic matter. This naturally 

 leads to the question of how far these conditions are under our 

 controul, because if they are so to any extent, it is evident that 

 that mode of cultivation must be most desirable, in which the 

 largest amount of vegetable matter is formed, at the least ex- 

 pence of inorganic matter. 



The plant selected for some experiments on this subject was the 

 Red Mangel Wurzel, which was cultivated in rich soil, abundantly 

 supplied with animal manure. A fair average plant was examined 



