LIME. 



LIME. 



being formed and hardened in the interior of 

 the organized material, protects it from farther 

 decay. For this reason it may be used to pre- 

 vent excessive fermentation in the dung-hill; 

 and to the same properties we may in part 

 ascribe its utility in the soil, viz., that of per- 

 mitting the slow and gradual decay of organic 

 matter in quantities suited to the demands of 

 vegetation. It has been supposed that the 

 chief value of lime as a manure lay in its 

 caustic or destructive effects, but that this po- 

 sition is untenable is proved by the successful 

 application of marls, and even powdered lime- 

 stone, which are robbed of their caustic quali- 

 ties. Sir H. Davy and others who have writ- 

 ten on the subject of agriculture, refer the 

 utility of lime to its causticity, and state that 

 'chalk, marl, or carbonate of lime will only 

 improve the texture of the soil or its relation 

 to absorption; it acts merely as one of the 

 earthy ingredients.' This view is unquestion- 

 ably- incorrect, for it has been known to pro- 

 duce astonishing effects on peaty soils, when 

 applied in the form of carbonate and not caus- 

 tic lime, and powdered limestone as well as 

 marl have been successfully used on ordinary 

 soils. Besides, if ' the formation of soluble 

 matter from insoluble organic materials' be 

 the chief effect of lime, this effect should 

 take place immediately, while the lime is in 

 its caustic state ; but it appears that it soon 

 becomes carbonated in the soil, or by exposure 

 to the air, and yet its useful effects are more 

 perceptible a considerable time after its appli- 

 cation, and may be perceived for many years. 

 Whence it appears that its action on organic 

 matters in the soil is continued (probably not 

 increased) in the soil after carbonation. 



"Much of the vagueness in descriptions re- 

 lative to the use of lime has arisen from an 

 imperfect knowledge of the organic constitu- 

 ents of soils, which have lately been partially 

 developed. Authors have divided the organic 

 matter into soluble and insoluble, by the for- 

 mer of which we understand the humic, crenic, 

 and apocrenic acids, and by the latter, hiunin, 

 humus-coal, and vegetable fibre; and they state 

 that lime is injurious where there is much 

 soluble matter in the soil, as it forms insoluble 

 combinations. The truth is, the humate of 

 lime is partially soluble, the crenate somewhat 

 so, and the bi-crenate very soluble. Now, by 

 admitting these acids as active ingredients in 

 soils, we are at no loss to account for the 

 utility of carbonate of lime, for the weak affi- 

 nity of the carbonic acid is overcome by their 

 superior attraction, and more soluble salts are 

 formed which may then be received into the 

 rootlets of plants. There can be no doubt, 

 however, that caustic lime is of greater benefit 

 where a soil contains humin and vegetable 

 fibre, as it promotes their incipient decomposi- 

 tion. The utility of lime, therefore, is three- 

 fold : first, that of decomposing organic matter, 

 and rendering it a suitable nourishment for 

 plants ; secondly, that of combining with orga- 

 nic matter and rendering it capable of being 

 received into the vessels of vegetable organ- 

 ization for promoting vegetation ; and, lastly, 

 that of lengthening the time of decomposition 

 of organic matter, which, therefore, yields nu- 

 91 



trition in proportion to the demands of a plant 

 in the progress of its growth. 



" It has been supposed by many to be neces- 

 sary that lime should be caustic, as. it is only 

 then soluble, but it should not be forgotten that 

 the carbonate is also soluble in water contain- 

 ing carbonic acid ; and farther, it is not neces- 

 sary that either the carbonate or quick-lime 

 alone should be dissolved in order to explain 

 its influence in vegetation, for moisture, the 

 medium of chemical action, is always present 

 in the soil, and assists in its soluble combina- 

 tion with the organic acids. There is, how- 

 ever, another action of lime with reference to 

 the soil itself, which is of importance, viz., that 

 it renders clayey lands looser, and sandy soils 

 more tenacious. The latter of these contrary 

 effects is of a chemical character, and there is 

 little doubt that lime acts like mortar by com- 

 bining the particles of sand together. The 

 former is partly mechanical, the mingling of 

 less cohesive earthy matter with the clay, and 

 partly chemical, in which the lime dissolved by 

 rains is washed into the crevices and cracks 

 of the clay, where, becoming carbonated, it 

 prevents their farther adhesion. To effect 

 these results most powerfully, it is evident 

 that the lime should be employed in a caustic 

 or water-slaked state. According to these 

 views, therefore, it is a matter of less moment 

 on what kind of land lime should be spread, 

 as it tends to ameliorate its condition or tex- 

 ture, and is the medium of conveyance of nu- 

 trition to vegetable life. 



"Nearly all the limestone employed in Dela- 

 ware for spreading on the soil is magnesian, 

 and it is therefore worth investigating how far 

 the magnesia may be injurious. One of the 

 first limestones employed for this purpose in 

 Pennsylvania, from which lime derived much 

 of its reputation as a manure in this section of 

 country, and which has not lost its character 

 to the present time, is nearly of the same com- 

 position with Jeanes' stone ; a very fair proof 

 that such a content of magnesia is not inju- 

 rious under certain circumstances. Sir H. 

 Davy's view of the subject appears to be cor- 

 rect, that magnesia in a caustic state is inju- 

 rious, but that when carbonated it is beneficial. 

 It was stated that it remains caustic for a long 

 time exposed to the air, and particularly when 

 mingled with lime; therefore, in employing a 

 magnesian limestone, if there is little vegetable 

 matter in the soil it will be apt to injure the 

 crops; but this effect may be obviated by 

 mingling it with fermenting manure, which 

 will rapidly carbonate it. There is another 

 view of the subject which has never been 

 broached, viz., the influence of the organic 

 acids in the soil. If much humic acid be pre- 

 ent, it will form humate of magnesia, soluble 

 in 160 parts of water, while humate of lime 

 requires 2000, so that it will be taken up in 

 greater quantity than lime. But by referring 

 to the quantity required by plants as shown 

 by an analysis of their ashes, we find that oak 

 requires about 5 times as much lime as mag- 

 nesia, and that ashes of straw yield nearly 12 

 per cent, of carbonate and phosphate of lime, 

 and no magnesia, from which it would seem 

 that the latter is injurious to plants from its 

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