No. 6. DEPARTMENT OF AGRICULTURE. 407 



paper must »bow tliat the answer can not be the same under all cir- 

 cumstances. Many authorities assume that practically all the lime, 

 however prepared, that comes into action in the soil, is, before it has 

 had time to react upon the mineral or organic matters, converted to 

 either a neutral or an acid carbonate; and that, therefore, the main 

 (juestion is ui)on the liual state of subdivision of the carbonate. 

 While such condition must eventually occur, the writer's experience 

 does not permit the conclusion that the change is as immediate as 

 has been generally assumed. Scientific experiment has shown the 

 caustic lime far more active in amending stiff, runny clays. For this 

 purpose, therefore, air-slaked lime, especially such as has been long 

 exposed to the air, and thereby largely converted to calcium carbon- 

 ate, is not to be commended. Ground stone lime and finely powder- 

 ed, water-slaked lime packed in barrels, are now extensively adver- 

 tised. A patent has been taken out for slaking lime, piled on a slope 

 and covered with a layer of air-slaked lime, it being claimed that 

 by this process a very finely divided, carbonic acid-free slaked lime 

 can be obtained. No doubt these excellent products can be advan- 

 tageously' employed in manj' regions remote from cheap lime; but 

 carefully w^ater-slaked lime, home prepared from most of the limes 

 so readily found in middle and eastern Pennsylvania, will probably 

 be found more economical for farmers of these localities. This much 

 should ijossibly be said for the ground limestone, that Patterson. (21) 

 found from five years' trial, that lime slaked in the soil gave a larger 

 return than that slaked before application. He also found that 

 weight for weight, shell lime and stone lime were equally eflScient, 

 despite a common impression to the contrary. 



Where the correction of acidity, the promotion of nitrification or 

 tlie prevention of undesirable reversion of phosphoric acid is sought, 

 doubtless the carbonate will be as valuable as the caustic lime, if it 

 can be cheaply sub-divided and thoroughly distributed; in fact, how- 

 ever, burning and air-slaking is the cheapest process of preparing a 

 very fine carbonate of lime. The question assumes especial import- 

 ance in case of sandy soils, whose humus supply is, at test, rather 

 low, and whose w^ater-holding capacity is largely measured by the 

 humus it retains. On such soils, unless the dressings are very light, 

 finely divided carbonate forms are to be preferred. 



The writer has repeatedly urged, on the score of safety and 

 economy, the use of smaller dressings of lime than are usually ap- 

 plied, excepting those cases in which the character of a runny clay is 

 to be changed. Fleischer, (22) after a large experience with moor 

 lands, similar in many respects to the peat beds so many enterprising 

 farmers in northern Pennsylvania are preparing for onion and celery 



(21) Lioc. clt. 



(22) Jahresbincht t. Agrlk-Chem. , 1898, 136. 



