46 



ON THE USE OF LIME, MARL, AND SHELL-SAND. 



will become sooner exhausted than would have been the case had 

 no lime been used at all. 



On the Composition of Soils not benefited by Lime. 

 Generally it may be stated that all soils containing more than 

 4 per cent, of lime are not benefited by lime. If a soil, there- 

 fore, naturally contains 10 or 20 per cent, of carbonate of lime, 

 we need not wonder that lime does not produce any good effect. 

 It must not be inferred from this observation that I think all 

 soils containing less than 4 per cent, of lime require lime. I 

 am quite aware that this is not the case, and have become ac- 

 quainted with excellent soils containing only 1J or 2 per cent, 

 of lime, and which are never limed, and yet maintain their fer- 

 tility. For all I know, there may be others which, although 

 they contain rather more than 4 per cent, of lime, may still be 

 improved by the use of lime. Experience alone can here be our 

 guide, and, as far as my experience goes, I have found that lime 

 does no good upon soils containing more than 4 per cent, of lime, 

 and that, generally speaking, the application of lime to land 

 need not be renewed if the proportion of lime in the land still 

 amounts to If to 2 per cent. But I have now to give the com- 

 position of four soils upon which I believe lime is largely 

 used : 



Composition of Soils from Longsutton (No. I.) ; from Mendip (No. II.) ; 

 and two Soils from Street, Glastoribury (No. III., a, 5). 



a. MECHANICAL ANALYSIS. 



No. III. 



100-00 100-00 100-00 100-00 



5. CHEMICAL ANALYSIS. 



Moisture 



Organic matter and water of combination 



Oxide of iron and alumina 



Carbonate of lime 



Insoluble si licious matter 



Magnesia and alkalies 



100-00 100-00 100-00 100-00 



The soils from Mendip and Longsutton, according to the 

 characters of their constituents, are marly loams ; the two others 

 stiff calcareous clays. 



The Longsutton soil contains many white soft particles of 



