THE MODE IN WHICH LIME OPERATES. 



333 



THE MODE IN WHICH LIME OPERATES 



IN RENDERING THE SOIL BETTER ADAPTED FOR THE GERMINATION AND 

 GROWTH OF PARTICULAR PLANTS. 



BY ROBERT jrTURK, ESQ., OF HASTINGS HALL, DUMFRIESSHIRE. 



[Premium, the Silver Medal] 



[A FAVORITE practice in Maryland, where clo- 

 ver is much relied on for restoring worn-out 

 lands, and for maintaining the strength of such 

 as have been recruited, is to sow the clover- 

 seed on the snow, in February, and leave it 

 without any covering except what it gets by 

 sinking into the ground, on the melting of the 

 snow and the alternate thawing and freezing in 

 spring — othei-wise it is sowed, in like manner, 

 on the surface, later in spring, but generally be- 

 fore the cessation of frost. Sometimes, as was 

 the case last spring, the young cl8rv-er is killed 

 by a severe fro3t occuring just when the young 

 clover is coming up, but generally this system 

 of sowing appears to answer well. It is usual- 

 ly on the young wheat or oats — harrowing is 

 sometimes resorted to but very rarely. Where 

 the land is light it is deemed advisable to roll 

 the clover-seed which may serve to give more 

 compactness to that sort of land, liable as the 

 young grain crop is to be injured by the March 

 winds. It would seem clear from the experi- 

 ments here detailed, that covering the seed is 

 not necessary to its germination, and that when 

 it is done, it cannot be done too lightly.] 



There is no substance, perhaps, so exten- 

 sively used for agricultural purpo.ses, with re- 

 gard to whose agency, and the time of apply- 

 ing it to the soil, the opinions of practical men 

 have differed so widely as that of Lime ; for, 

 while it has been, and, I may say, is at the pros-* 

 ent time, regarded by one class of agriculturists 

 as a manure, it is by another, and, perhaps, not 

 the ^vorst-informed clas.s, regarded merely as a 

 stimulant ; that of itself it contributes almost 

 nothing to the growth of plants, and that the 

 benefit resulting from the application of it to 

 the soil is owing entirely to the action which it 

 exerts upon other bodies which it encounters in 

 the soil. It would not be difficult to show that 

 lime, like the other earthy bodies, enters so 

 sparingly into the constitution of plants, that its 

 presence, in many whose growth it promotes, 

 can, upon analysis, with difficulty be detected, 

 and we are, therefore, entitled, perhaps, to re- 

 gard its presence, on .some occasions, as acci- 

 dental rather than as a necessary constituent. — 

 Were Lime really entitled to be regarded as a 

 manure, ■we are inclined to think that its ef- 

 fects ^vould be less evident than they really are, 

 especially when we take into consideration the 

 very small proportion in which it is found to ex- 

 (697) 



ist in those plants which are considered as most 

 worthy of cultivation, and for promoting the 

 growth of which it is most frequently applied. 

 To what, then, are we to attribute the increased 

 fertility of these soils which have received a 

 due proportion of Lime ? Most certainly not to 

 the mfluence which it exerts over the earthy 

 bodies which constitute the soil, these being 

 saturated metallic oxides, which have no affinity 

 for it. Nor has Lime an affinity for auy of the 

 elements which they contain ; and, if the soil 

 did not contain other ingredients, upon which it 

 powerfully acts, its application would be follow 

 ed by no beneficial results. These ingredients 

 are the remains of bodies which have lived and 

 died, and still, in some degree, retain their or- 

 ganization ; and, in proportion to tlie quantity 

 of decomposable matter which they contain, 

 and the causticity of the Lime when applied to 

 them, will be the effect produced. If, then, the 

 action produced by the Lime depends so much 

 upon the state in which it is applied, it is also 

 proper that we should mention that its caustici 

 ty depends, frst, upon the freeness from other 

 earthy matters, or, in other words, its purity ; 

 and, sccoudh/, on the time tliat is allowed to 

 elapse between the burning and the application ; 

 the burning being simply the means by which 

 the carbonic acid is expelled, and the Lime be- 

 ing thereby changed from a mild to p caustic 

 state, or, as it is called, quick-lime. Water is 

 then applied, for the purpose of slaking or pul- 

 verizing it, in order that its distribution over the 

 land may be more equal, and effected with 

 greater facility. But, from the time it is cooled, 

 after it comes from the kiln, its affinity for car- 

 bonic acid gas is very strong, and it will con- 

 tinue to attract it from the atmosphere till it is 

 again united to a proportion C(iual to what was 

 expelled by the operation of buraing ; and if 

 this is allowed to take place before it is applied 

 to the soil, it returns to a state comparatively 

 inactive, and, in proportion as it has been al- 

 lowed time, and placed under circumstances 

 favorable for attracting carbonic acid gas, it 

 will lose the power of acting upon, or disorgan- 

 izing the animal or vegetable remains which it 

 encounters in the soil, and also of neutralizing 

 any acidulous matter which ma.v there exist. 



We shall now endeavor to explain the nature 

 of the action which L ime exerts upon the organ- 

 ized matter it encounters in the soil, and in 

 what manner this action tends to promote the 

 generation and growth of particular vegetables. 



When a plant dies, it leaves its roots in the 

 soil; and the roots of some plants occupy a 

 much larger space than a person unacquaintej 

 with their growth may suppose. The softer 

 and more juicy parts begin to rot or to be de- 



