THE FARMER'S MAGAZINE; 



211 



cart-loads, and from ^8 to 15 loads of a waggon. The 

 expanse of carrying a crude heavy article very much 

 restricts the use of the substance, and chalk in the 

 original state falls under the list of these materials. 



The use of chalk as a top-dressing is best obtained in 

 the form of a compost with earths and peat, as is the 

 case with ail calcareous substances. It is a mild agent, 

 and possesses no destructive solvent quality, which at- 

 taches to the lime-stones after undergoing the action of 

 fire. In an unmixed state chalk absorbs moisture and 

 attracts acids, which hasten putrefaction, and the me- 

 chanical action lies in uniting with clays, and forming a 

 resemblance of marl, and preventing the hardness of the 

 land in summer, and the wet adhesiveness in winter. 

 On grass lands it has the usual property of a manure of 

 any kind in banishing the coarser herbage, and bringing 

 in the place of it the white clovers and grasses of a 

 sweeter quality. Chalk has a very strong affinity for 

 water, and consequently is most useful on dry lands 

 and gravels, by attracting and retaining moisture for the 

 use of the growing plants ; and this use is very much 

 assisted by being mixed with earth?, and brought into 

 contact with animal and vegetable remains in a state of 

 minute subdivision, which settle downwards into a stra- 

 tum around the roots of the plants, and form the source 

 whence the nutriment is drawn and which was formed 

 by the application. Hence arises the superiority of 

 earthy substances for the purpose of top-dressing, over 

 the effects of caustic stimulants. The latter exert a 

 passing influence on the growing bodies of the moment, 

 but leave no earthy residuum as a source of future use. 



At a minimum calculation, the expense and dressing 

 of unmixed chalk cannot be less than £i per acre, or 

 40 cart-loads at 2s. each. This amount supposes a 

 favourable contiguity of the chalk and of the land on 

 which it is to be used. When made into composts the 

 expense will be very similar, as the smaller number of 

 cart-loads per acre will meet the cost of collecting the 

 earths and turning over the heaps. In very many 

 situations the cost will be considerably above ^4, owing 

 to the expense of carriage and the quantity of the article 

 that is required to produce any effect. If this quantity 

 be not large the expense will be wholly lost, for quantity 

 is most imperatively required, in many cases, to rise 

 into a superior affinity. The most important recom- 

 mendation must not be omitted — that all aggregate 

 bodies that are used in top-dressing must be reduced to 

 a finely-pulverized state. Lumps of chalk will lie on 

 the surface of lands without being broken ; the plough 

 and the harrow turn them over, and the roll presses 

 them into the ground ; but the purpose will be entirely 

 defeated unless the body is finely reduced. Well-pre- 

 pared composts have an advantage in this way. 



On soils of the lighter description — sands, loams, 

 gravels, and even on chalky lands — very great improve- 

 ments have been done by large applications of chalk ; 

 the efi\;cts of which have not ceased with a few crops, 

 but have operated, like all calcareous substances, in 

 imparting properties to the land that it did not before 

 possess, and at the same time increasing the quantity of 

 every crop. The quantity applied must be large, both 

 on arable and grass lands ; on the latter an earthy com- 

 post is preferable, and largely increases the bulk of 

 herbage, which by its decomposition affords the most 

 valuable food of subsequent crops. In a state of grass 

 the value lasts for many years, in a full third of increase. 

 The great value of earthy top-dressings consists in the 

 vegetable stratum that is formed by the roots of the 

 plants along with the residuum of the manure. 



No. in.— Clay and Lime. 



Clay is a mixed body, mostly composed of alu- 

 mina, sulphuric acid, and water. It is found in vast 



beds in the alluvial deposit of the tertiary formation, 

 of which chalk, or the most recent condition of lime, 

 forms the basis, and is much mixed with other bodies 

 in different states and combinations. The prevailing 

 colour is brown or reddish brown, yellow, and some- 

 times bluish; sandy, gravelly , often solid, more or less 

 unctuous, and soft to the touch, often friable and dry, 

 breaking into small lumps, containing more silex, and 

 loses its plasticity ; and perhaps no body is found in a 

 greater diversity of composition, in soils and in slates, 

 and in all argillaceous formations. It enters into all 

 good lands — in fertile soils from 9 to 15 per cent., and 

 in barren lands from 20 to 40 per cent. The absence of 

 it forms a soil too dry and porous, and a superabundance 

 of it constitutes a soil too wet and cold when in a moist 

 state, and contracts and hardens by heat into a condi- 

 tion adverse to vegetable life. Clay is found calcareous, 

 meagre, and unctuous, effervescing with acids, rough 

 and gritty, and containing a greater quantity of alumina. 

 The purest specimen contains upwards of GO per cent, of 

 sand, and is always mixed with mineral, animal, and 

 vegetable substances. The aluminous base imbibes 15 

 times its own weight of water without dripping, and 

 retains it with great obstinacy. 



Like other substances, the quality of the clay, the 

 mode of its combination with other substances, and the 

 exposure of the combined elements, render it a fertili- 

 zer, both in the simple state, and in the condition of a 

 compost with other substances. When found of a 

 clammy or indurated texture, great difficulty is experi- 

 enced in reducing the substance to particles that can act 

 with and upon the other elements with which the con- 

 tact will occur. But with calcareous clays, the process 

 is easy. The mass is friable and crumbling, and the 

 dissolution is so fine as to allow an intimate incoi'pora- 

 tion with the soil. Accordingly very great improve- 

 ments have been effected by excavating clays of this 

 nature, and laying large quantities of it on the surface 

 of light lands. A moist quality has been conferred on 

 the sandy soil, and more firmness, and a greater con- 

 sistency. The quantity must be liberal — from 100 to 

 160 cart loads to an acre — and must be attentively used 

 in the breaking and spreading of the pieces. On the 

 other hand, ferruginous clays, and those of a white 

 sandy and gravelly nature, are positively pernicious, and 

 require to be mixed with substances of a better quality, 

 to correct the noxious property, and also an exposure to 

 atmospheric action, to extract and dissipate the hurtful 

 effluvia. A total alteration must be acted upon the con- 

 stituents before clays of that nature can be made fertile, 

 either as a cultivated soil, or as an application to other 

 lands. 



Sulphuric acid in any form or combination is noxious 

 to vegetable life, and in preparing clay for the purpose 

 of acting as a manure, that hurtful ingredient must be 

 banished, and more friendly qualities introduced. The 

 quantity of acid and water amounts to two-third parts 

 of the constituents of pure clay, and being in combina- 

 tion, the destruction of both elements must be effected. 

 Some body must be applied that will act violently and 

 forcibly in disintegrating the mass of clay, in sundering 

 the particles, in banishing the existing properties, and 

 in conferring more valuable qualities by means of reci- 

 procal action and mutual combinations. For this pur- 

 pose no better agent has yet been found than caustic 

 lime, in a state of hot cinders newly burned. Lime is 

 the oxide of calcium, one of the newly discovered terri- 

 genous metals, which contains in 100 parts about 38 of 

 oxygen. An oxide is a sour pungent body, which draws 

 off every volatile substance without fusing the primitive 

 body ; it is the circumstance or state of change, while 

 calcination is the mode of effecting it. By the appli- 

 cation of a violent heat, lime loses the water of crystal- 



