Mance: Quarry Industry of Southern Indiana 125 



When this water-slaked Kme comes in contact with the air 

 it tends to take up carbon dioxide from the air and to change back 

 to calcium carbonate. The reaction takes place as follows: 



Ca(0H)2 + COo = CaC03 + H2O 



In addition to the fact that the crushed limestone is as effective 

 as lime on the soil, since both do the same work thru the same 

 chemical reactions, the quicklime is far more destructive of the 

 organic matter that might be present in the soil. The use of 

 crushed limestone is accompanied by less inconvience than the 

 use of the lime. The latter is injurious to the skin and must be 

 handled with care. The burned lime, in addition to being a 

 powerful chemical agent in the destruction of animal matter, 

 tends to increase the solubility of the phosphorus and potassium 

 in the soil. Altho this may give larger crops at the time of dressing 

 the soil, it tends presently to cause a rapid impoverishment of 

 the field. Since the main object of the use of lime or limestone 

 on land is to correct the acidity of the soil and thereby increase the 

 amount of nitrates present, the use of ground limestone is just as 

 effective as lime dressing and is less expensive. Where the soil 

 is especially rich in organic matter, as in the case of peaty and 

 other swamp soils, the quicklime is probably the better dressing 

 because such a soil can spare a large amount of its organic matter 

 without becoming impoverished. There are types of soil also 

 that contain large amounts of phosphorus and potassium which 

 become available very slowly, and in such cases the use of lime 

 will hasten the liberation of these necessary plant foods. Pro- 

 fessor Hopkins says {op. cit., p. 164) : 



Of course, the landowner must be governed somewhat by the cost of the 

 material. As a rule, fine-ground limestone will be both the best and the 

 most economical form of Hme to use, wherever it can easily be obtained. 

 If caustic lime is used, we should make special provision to maintain the 

 humus in the soil by making even larger use of farm manure, legume crops, 

 and green manures. 



It might be expected that burned lime would produce a greater increase 

 in the crops for the first year or two than would be produced by ground 

 limestone, more especially where the mineral elements, phosphorus and 

 potassium, are not applied; for . . . ground limestone produces only 

 the milder action, chiefly of correcting the acidity of the soil and thus en- 

 couraging the multiplication and activity of the nitrogen-gathering and 

 nitrifying bacteria; whereas, the burned lime not only produces this same 

 effect, but it also acts as a powerful soil stimulant, or soil destroyer, attacking 

 and destroying the organic matter and thus liberating plant food from the 

 soil, usually resulting in more or less waste of valuable nitrogen and humus. 



