I905J 



The Use of Lime. 



405 



Chalk, after the flints are removed, is usually a very pure form 

 of carbonate of lime, but even when fairly pure it contains little 

 more than the equivalent of about 50 per cent, of lime (CaO). 

 For this reason, and also because it is unburned, much more 

 chalk than lime is applied per acre. Chalk acts somewhat like 

 lime but more slowly, and although useful for checking finger- 

 and-toe is not so efficacious as lime. 



Marls are really mixtures of earthy matter and carbonate of 

 lime, but their consideration is beyond the scope of this paper. 



It maybe well to state here that while good lime (lime shells) 

 may contain 90 per cent. Of lime (CaO), fresh gas lime contains on 

 the average only about 34 per cent., and chalk only about 52 per 

 cent of the same substance. It therefore requires over 2\ tons of 

 fresh gas lime and about if tons of chalk to supply the same 

 amount of lime as is contained in a ton of the best lime shells. 



As has already been stated, the use of lime is now considerably 

 restricted. Careful experiments have shown that the good effects 

 of lime for pasture can usually be more economically obtained 

 by basic slag than by lime, a method of manuring by which the 

 farmer gets an excellent phosphatic manure to supply him 

 with lime free of cost. Basic slag usually contains about 45 per 

 cent, of lime, about a third of which is probably in the active 

 form. A dressing of half a ton of basic slag per acre therefore 

 supplies as much lime (partly free and partly in combination) 

 as is contained in 5 cwt. of ground lime. It is only on pastures 

 rich in organic matter and plant food that liming is now likely 

 to be profitable. 



For arable land poor in lime the application of lime is still 

 most desirable, this being especially so where swedes and turnips 

 suffer from finger- and-toe disease. There is no doubt also 

 that the quantity of corn crops is considerably improved by 

 judicious liming, especially on soils of a somewhat moorish 

 character. The old practice on such soils in the West of Scotland 

 of harrowing in a light dressing of slaked lime at the time of 

 sowing the corn crops is a most beneficial one. 



The importance of guarantees as to the purchase of burnt 

 lime (lime shells) or ground lime has already been urged. 

 Very many of the limes now on the market contain con- 

 siderably less than 85 per cent, of lime, some of them having 



