PREFERABLE FORM OF LIME 597 



fication, apparently require its presence for neutralizing the acid 

 formed. In general, it may be said that the presence of lime 

 hastens the destruction of organic matter. . 



It is difficult to say just what soils will be improved by liming 

 and what will not, and it is a matter which must be settled by 

 experiment in each case. As a rule, heavy clays and loams are 

 benefited, yet of two such soils, apparently identical, one may 

 not be affected in any marked degree while the other may readily 

 respond to treatment. Sandy soils are often improved but some- 

 times not. Sour, boggy lands, are usually improved by the ad- 

 dition of enough lime to neutralize their undue acidity. Marsh 

 grasses and plants are more tolerant of acid in the soil than tame 

 grasses are, so that in unlimed soil the former run out the latter. 

 The application of lime alone to a very poor soil does not pay. 



The particles of lime resting in the soil are partially dissolved 

 by the next rainfall after application, or by the soil moisture, 

 forming lime water, and the lime is distributed in this form 

 through the soil to some extent. It all probably soon becomes 

 converted into carbonate as ground air is usually quite rich in 

 carbon dioxid. Indeed, for many soils, it is immaterial whether 

 lime be applied as lime or as carbonate, granting, of course, that 

 the latter be ground to a fine powder. Economy is in favor of 

 the lime, however, not only because it needs no grinding, but 

 because it is lighter than the corresponding amount of carbonate, 

 making a saving in transportation. The difference is quite consid- 

 erable, 56 pounds of lime being equivalent in effect to 100 pounds 

 of carbonate. For these reasons as well as because it possesses 

 some valuable properties not shared by the carbonate, it is pro- 

 bable that for most localities lime is to be preferred to any form 

 of ground oyster shells, ground limestone, marble dust or the like. 



One of these valuable properties not possessed by limestone, is 

 said to be that of acting as a fungicide and insecticide. As a 

 rule, fungi prefer acid reaction in the substances in which they 

 grow, so that the strongly alkaline properties of lime may make 

 a limed soil unsuitable for their growth. 



502. Preferable Form of Lime. Burned lime or slaked lime 

 as has already been said, is to be preferred to lime carbonate where 



