72 



FARMERS' REGISTER 



[No. 2 



MINERAL MANURES. 



Extract from No. 46 of the Farmer's Series of the 

 Library of Useful Knowledge first published in Lon- 

 don, Nov. 13, 1833. 



Th« manures we term alkaline and calcareous 

 con:?ist chiefly of those substances which combine 

 with acids, though generally with tlie l^ss of then- 

 distinctive characters, and out of which lime may 

 be extracted by the process of burning. The ex- 

 tent of their utility is only ascertained by practice, 

 which does not speak a unitbrm language in every 

 phice, for scarcely a liirmer is to be found who is ac- 

 quainted with the exact effects of their properties 

 upon soils; from which it may be readily imagined 

 that many will Ibrm erroneous opinions, arising 

 out of the local circumstances of their own farms. 

 Their chief advantage, in a natural state, seems, 

 however, to be rather mechanical and alterative, 

 than nutritive. They form a uselul component 

 part of the earth; and, in certain proportions, they 

 are found to be essential to the fertility of most 

 soils, or 'perhaps necessary even to their proper 

 texture, as an ingredient in the organs of plants.*" 

 The primitive constituents of which they are 

 formed are composed of chalk, of limestone, or of 

 the shells offish — and on being submitted to the 

 action of fire, lime is [)roduced. 



Chalk 



Is a pure calcareous earth, though in almost all 

 cases mixed with particles of clay and sand, 

 which deteriorate its quality, in whatever propor- 

 tion they exist; it is, therelbre, highly important 

 that the farmer should ascertain those proportions, 

 for, when combined with clay, such chalk is most 

 fit tor light loams and sandy soils, which it tends to 

 unite, while stiff lands will, on the contrary, be pro- 

 portionably most benefited by the opposite mix- 

 ture, and s'hould be applied in the different propor- 

 tions which the respective qualities of each seem 

 to require. It is, however, trequently laid wiih- 

 out discrimination upon every kind of land, though 

 the proper number of bushels necessary for each 

 particular soil can only be accurately determined 

 by a descriminaling knowledge both of the difier- 

 ent properties of the chalk, and of the ground to 

 which it is intended to be applied. From igno- 

 rance of this, farmers are generally without any 

 rule to guide them in its application; but supposing 

 them, from long experience, to have discovered 

 the exact quantity of some particular chalk pro- 

 per for their own soil, this knowledge can only be 

 local, and cannot enable them to decide upon its 

 effect in other situations.! 



■^ Sir Humphrey Davy. Agr. Chem., p. 19. 



\ 'Pure chalk, being saturated with carbonic acid 

 gas, tends to alter the original disposition of the i)arts 

 of the soil, where it meets with various substances, 

 either vegetable, animal, or mineral; these substances 

 becoming oxygenated by their action with the chalk, 

 generate their several acids, and these acids disengage 

 the carbonic acid gas, whicli is readily absorbed by the 

 roots of the j)lants; it therefore tends, by slow degrees, 

 to separate the cohesiveness of the strong soil, and to 

 admit the roots of the plants to feed upon the carbon 

 with greater facility.' — Malcolm's Comp. of Ilusb. 

 and Anal, of Manures, vol. ii. p. 32. 



When unmixed, its properties in all respects re- 

 semble those of pure lime, and the chief motive for 

 burning either that, or limestone, is, that it may 

 be thertby the more easily reduced to that stale 

 of powder, and sfjread upon the ground, by whicli 

 it can be rendered a more effectual dressing for 

 land. The operation also considerably reduces its 

 weight by the evaporation of the water contained 

 in it, so that, in case of very distant carriage, the 

 cost of fuel nmy be saved by the difference in the 

 expense of conveyance. 'J'he cost of delivery 

 from any great distance is indeed so considerable, 

 as almost to preclude its use, except in the imme- 

 diate vicinity; and even there, it is usually carted 

 upon the land during hard fros s, when the teams 

 are not otherwise occupied. Wlien laid up/on the 

 land in the simple state of chalk, it is also ap.t to 

 become hard by the drying effects of the wind and 

 air, and as it is dug up in large lumps which can- 

 not be reduced without considerable labor, it thus 

 remains for a considerable length of tune, without 

 producing its intended eficct upon the soil. When 

 thus used, therefore, it should be taken fi-om the 

 pit in either the latter part of the autumn or the 

 the beginning of winter, while its pores are full of 

 water; for if frost then comes on, it becomes ex- 

 panded in the act of freezing, and thus bursting 

 suddenly, it crumbles partly into a kind of slime. 

 This, however, leaves the operation to chance; it 

 is, therefore, better to break the chalk into as fine 

 pieces as possible: for otherwise, being exposed 

 to the winds of the spring months, it becomes so 

 dried and hard, that the harrows will take no ef- 

 fect upon it, and to roll it, will only serve to com- 

 press it into the earth witliout breaking it. By 

 this irregularity, too, in its division, a great deal 

 of the seed would also remain uncovered, and 

 its period of ri|;ening being thus more forward 

 where the manure was laitl than where the land 

 was left bare, a porfon of the crop would be ready 

 to be reaped while the remainder might be still 

 green. 



From this difficulty, the use of chalk has been 

 much discontinued, though the fault is not so 

 much in the chalk itself as in the manner of treat- 

 ing it. Regard must necessarily be had to the 

 quality of the chalk, to the tenacity of the soil, 

 and also to its state of poverty or improvement. 

 The quantity laid upon the land is variable, and 

 more governed by convenience than by any scien- 

 tific notion of its properties: ti'om 400 to 600 or 1000 

 bushels, and even more, is by no means unusual. 

 It IS very commonly laid upon coarse sour pasture 

 at the rate of 150 to 2-30 bushels per acre, upon 

 whicli it almost unilbrmly effects an evident im- 

 provement, bringing it from a rush-like appear- 

 ance, to a fine, sweet, and delicate herbage, inter- 

 mixed with white clover and the richer grasses, 

 which otherwise remain dormant in the ground. 

 The same good effect is also found when applied 

 to hot gravelly loams, where its cooliiiiJlJroperties 

 counteract th.cir tendency to burn in the summer 

 months; ami on laud subject to sorrel it is a sove- 

 reign cure, killing that weed speedily — a circmn- 

 slance liivorable to stock, for it is very unwhole- 

 some to sheep, and many lambs are frequently 

 killed by eating it. J It also inqiarts a mellowness 



X Malcolm's Survey of Surrey, Kent, and Sussex, 

 vol. li. p. 30 — 39; Young's ditto of Hertfordshire p. 

 161. 



