390 LIME HASTE>-S ORGANIC DECOMPOSITION. 



lime as much time as possible to operate before a crop is taken from 

 land in which organic matter already abounds. Or where fermenting 

 manure is added, it advises the farmer to wail till spontaneous decom- 

 position becomes languid, when the addition of lime will bring it again 

 into action and thus maintain a more equable fertility. 



In a work upon soils, which 1 have fretjuently commended to your 

 notice, (Morton ''On Soils,'' third edition, p. 181,) you will fijsd the 

 following observations : — " Writers on agriculture have stated that lime 

 hastens the decay of vegetable matter, whereas the fact is, that it retards 

 the process of the decomposition of vegetable matter. If straw or long 

 dung be mixed with slaked lime, it will be preserved ; while if mixed 

 with an equal portion of earth, the earth will hasten its decay." The 

 two facts stated in ttiis last sentence are, I believe, correct, yet it is 

 nevertheless consistent both with theory and universal observation, that 

 lime in the soil promotes the decomposition of organic matters, both 

 animal and vegetable. This will appear more clearly when we come 

 to study the precise nature of the action of lime upon organic substan- 

 ces in general. 



The above remarks, in regard to the best time for applying lime, re- 

 fer chiefly to quick-lime, the state in which, in England, it is so exten- 

 sively used. Marls and shell-sands can cause no loss when mixed 

 with the manure, and therefore may with safety be laid on at any pe- 

 riod of the rotation. The same remark applies with greater force to the 

 lime composts. These may be used precisely in the same way as, and 

 even instead of, the richer manures — may be laid, without risk, upon 

 grass lands of any quality, and at any j)eriod — or as a top dressing on 

 the young com in spring, when the grass and clover seeds are sown by 

 which the corn crop is to be succeeded. And as the compost acts 

 more speedily than lime in any other form, it is especially adapted for 

 immediate application to the crop it is intended to benefit. To wet 

 lands also, it is well suited, and to such as are subject to much rain, by 

 which, while the surface is naked, the soluble matters produced in the 

 soil are likely to be very much washed away. 



§ 15. Of the effects produced by lime. 



The effects of pure lime upon the land, and upon vegetation, are ul- 

 timately the same, whether it be laid on in a state of hydrate or of car- 

 bonate. If different varieties produce unlike effects, the quantity of 

 lime applied being the same, it is because in nature lime is always 

 m®re or less mixed with other substances which are capable of modi- 

 fying the effects which pure lime would alone produce. The special 

 effects of marls, &c., when they differ from those of burned lime, are 

 to be ascribed to the presence of such admixtures. In general, how- 

 ever, riie chemical action of the marls and calcareous sands is precisely 

 the same in kind as that of lime in the burned and slaked state, and sc 

 far the effects which we have already seen to be produced by marls, 

 (p. 374,) represent also the general effects of lime in any form. 



These general effects may be considered in reference to the land on 

 which it is laid, and to the crops which are, or may 6c, made to grow 

 upon it. 



