Improving: the Condition of the Soil 



they are capable of producing good crops when well 

 treated, and respond freely to the manures. Where 

 chalk is clayey the quantity of clay is predominant, 

 and the proportion of calcium is sometimes reduced 

 to 10 per cent. In this case it ought not to be used ; 

 but with nearly 35 per cent, of limestone it is excel- 

 lent on sandy and dry lands. It decomposes less 

 quickly and less completely and is darker in colour. 



When chalk is sandy, the quantity of sand pre- 

 dominates. It would sometimes be 85 per cent. ; 

 when there is about 40 per cent, limestone, it is 

 very suitable for wet clayey land, because it makes it 

 at the same time less tenacious and more friable. 

 It does not form a sticky mud with water, and easily 

 decomposes. When it is dolomitic it contains a 

 considerable proportion of carbonate of magnesia, 

 sometimes 30 per cent, or more, and 50 per cent, of 

 carbonate of Ca. This form is very frequent in 

 England ; it is suitable for clayey soils, for pastures 

 in wet situations, and, generally speaking, for all 

 soils requiring limestone. 



One should avoid making lime of these magnesian 

 chalks, because the magnesia which they contain 

 by the transformation of carbonate of magnesia into 

 oxide of magnesia ; this magnesia is caustic, as we 

 have seen, to growing plants, and ought always to 

 be applied a long time in advance to the fallow. 



One should for choice employ each kind of chalk 

 on the soil which it suits, it then has a double value ; 

 that of the limestone carbonates is evidently the 

 most important, but that of the second element, 

 whichever it may be, is not negligible. The best 



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