Imágenes de páginas
PDF
EPUB

fear of contradiction, that no naturally poor soil, below the falls of the rivers, contains the smallest proportion of calcareous earth. Nor do I believe that any exception to this peculiarity of constitution can be found in any poor soil above the falls: but though these are far more extensive and important in other respects, they are beyond the district within the limits of which I propose to confine my investigation.

These results are highly important, whether considered merely as serving to establish my proposition, or as showing a radical difference between most of our soils, and those of the best cultivated parts of Europe. Putting aside my argument to establish a particular theory of improvement, the ascertained fact of the universal absence of calcareous earth in our poor soils leads to this conclusion that profitable as calcareous manures have been found to be in countries where the soils are generally calcareous in some degree, they must be far more so on our soils that are quite destitute of that necessary earth.

CHAPTER V.

ral times, so as to wash off all remains of the dissolved lime. These filtered washings are added to the solution, to all of which is then poured a solution of carbonate of potash. The two dissolved salts thus thrown together, (muriate of lime, composed of muriatic acid and lime-and carbonate of potash, composed of carbonic acid and potash,) immediately decompose each other, and form two new combinations. The muriatic acid leaves the lime, and combines with the potash, for which it has a stronger attraction-and the muriate of potash thus formed, being a soluble salt, remains dissolved and invisible in the water. The lime and carbonic acid being in contact, when let loose by their former partners, instantly unite, and form carbonate of lime, or calcareous earth, which being insoluble, falls to the bottom, is separated by filtering paper, is washed, dried and weighed, and thus shows the proportion contained by the soil.*

In this process, the carbonic acid which first composed part of the calcareous earth, escapes into the air, and another supply is afterwards furnished from the decomposition of the carbonate of potash. But this change of one of its ingredients does not alter the quantity of the calcareous earth, which is

RESULTS OF THE CHEMICAL EXAMINATIONS always composed of certain invariable proportions

OF VARIOUS SOILS.

PROPOSITION 2. Continued.

of its two component parts; and when all the lime has been precipitated as above directed, it will necessarily be combined with precisely its first quantity of carbonic acid.

and

The certainty of any results of chemical analysis would be doubted by most persons who This operation is so simple, and the means for have paid no attention to the means employed for conducting it so easy to obtain, that it will genersuch operations: and their incredulity will be the ally be the most convenient mode for finding the more excusable, when such results are reported by proportion of calcareous earth in those manures one knowing very little of the science of chemis- that are known to contain it abundantly, try, and whose limited knowledge was gained where an error of a few grains cannot be very without aid or instruction, and was sought solely material. But if a very accurate result is neceswith the view of pursuing this investigation. Ap- sary, this method will not serve, on account of sevpearing under such disadvantages, it is therefore eral causes of error which always occur. Should the more incumbent on me to show my claim to no calcareous earth be present in a soil thus anaccuracy, or so to explain my method, as to ena- alyzed, the muriatic acid will take up a small quanble others to detect its errors, if any exist. To an-tity of aluminous earth, which will be precipitated alyze a specimen of soil completely, requires an amount of scientific acquirement and practical skill, to which I make no pretension. But merely to ascertain the absence of calcareous earth-or if present, to find its quantity-requires but little skill, and less science.

by the carbonate of potash, and without further investigation, would be considered as so much calcareous earth. And if any compounds of lime and vegetable acids are present, (which for reasons hereafter to be stated, I believe to be not uncommon in soils,) some portion of them may be disThe methods recommended by different agri- solved, and appear in the result as carbonate of cultural chemists for ascertaining the proportion of lime, though not an atom of that substance was calcareous earth in soils, agree in all material in the soil. Thus, every soil examined by this points. Their process will be described, and made method of precipitation, will yield some small reas plain as possible. A specimen of soil of consult of what would appear as calcareous earth, venient size is dried, pounded, and weighed, and then thrown into muriatic acid, diluted with three or four times its quantity of water. The acid combines with, and dissolves the lime of the calcareous earth, and its other ingredient, the carbonic acid, being disengaged, rises through the liquid in the form of gas, or air, and escapes with effervescence. After the mixture has been well shaken, and has stood until all effervescence is over, (the fluid still being somewhat acid to the taste, to prove that enough acid had been used, by some excess being left,) the whole is poured into a piece of blotting paper folded so as to fit within a glass funnel. The fluid containing the dissolved lime passes through the paper, leaving behind the clay and silicious sand, and any other solid matter; over ich pure water is poured and passed off seve

though actually destitute of such an ingredient.
The inaccuracies of this method were no doubt
known (though passed over without notice) by
Davy, and other men of science who have re-
commended its use: but as they considered calca-
reous earth merely as one of the earthy ingredients
of soil, operating mechanically, (as do sand and
clay,) on the texture of the soil, they would scarce-
ly suppose that a difference of a grain or two
could materially affect the practical value of an
analysis, or the character of the soil under exam-
ination.†

be found in Kirwan's Essay on Manures, Rozier's
More full directions for the analysis of soils may
Dictionary,
and of calcareous manures in Appendix E.
and Davy's Agricultural Chemistry:
"Chalks, calcareous marls, or powdered limestone,

smallest portion of carbonate of lime-nor of the only other substance which might be mistaken for it, the carbonate of magnesia.

The examinations of all the soils that will be here mentioned, were made in the pneumatic apparatus, except some of those which evidently evolved no gas, and when no other result was required. As calcareous earth is plainly visible to the eye in all shelly soils, they only need examination to ascertain its proportion. A few examples will show what proportions we may find, and how greatly they vary, even in soils apparently of equal value.

The pneumatic apparatus proposed by Davy, as another means for showing the proportion of calcareous earth in soils, is liable to none of these objections; and when some other causes of error peculiar to this method, are known and guarded against, its accuracy is almost perfect, in ascertaining the quantity of calcareous earth--to which substance alone, its use is limited. The correctness of this mode of analysis depends on two well established facts in chemistry-1st. That the component parts of calcareous earth always bear the same proportion to each other-and these proportions are as forty-three parts (by weight) of carbonic acid, to forty-seven of lime. 2nd. That 1. Soil, a black clayey loam, from the top of the carbonic acid gas which two grains of calca- the high knoll at the end of Coggin's Point, on reous earth will yield, is equal in bulk to one ounce James River, containing fragments of muscle of fresh water. The process with the aid of this shells throughout. Never manured and supposed to apparatus disengages, confines, and measures the have been under scourging cultivation and close gas evolved-and for every measure equal to the grazing from the first settlement of the country: then bulk of an ounce of water, the operator has only (1818) capable of producing twenty-five or thirty to allow two grains of calcareous earth in the soil bushels of corn-and the soil well suited to wheat. acted on. It is evident that the result can indicate One thousand grains, cleared by a fine sieve of all the presence of time in no other combination ex- coarse shelly matter, (as none can act on the soil cept that which forms calcareous earth-nor of until minutely divided,) yielded sixteen ounce any other earth, except carbonate of magnesia, measures of carbonic acid gas, which showed the which, it present, might be mistaken for calcareous finely divided calcareous earth to be thirty-two earth, but which is too rare, and occurs in propor-grains. tions too small, to cause any material error.

2. One thousand grains of similar soil from another part of the same field, treated in the same manner, gave twenty-four grains of finely divided calcareous earth.

of bringing thirty to thirty-five bushels of cornnot a good wheat soil, ten or twelve bushels being probably a full crop. One thousand grains yielded eight grains of coarse shelly matter, and eighty-two of finely divided calcareous earth.

But if it is only desired to know whether calcareous earth is entirely wanting in any soil-or to test the truth of my assertion that so great a proportion of our soils are destitute of that earth- 3. From the east end of a small island, at the it may be done with far more ease than by either end of Coggin's Point, surrounded by the river, and of the foregoing methods, and without apparatus tide marsh. Soil, dark brown loam, much lighter of any kind. Let a handful of the soil (without than the preceding specimens, though not sandy drying or weighing) be thrown into a large drink-under like exhausting cultivation-then capable ing glass, containing enough of pure water to cover the soil about two inches. Stir it until all the lumps have disappeared, and the water has certainly taken the place of all the atmospheric air which the soil had enclosed. Remove any vegetable fibres, or froth, from the surface of the li- 4. From a small spot of sandy soil, almost quid, so as to have it clear. Then pour in gently bare of vegetation, and incapable of producing about a table spoonful of undiluted muriatic acid, any grain, though in the midst of very rich land, which by its greater weight will sink, and pene- and cleared but a few years. Some small fragtrate the soil, without any agitation being neces-ments of fossil sea shells being visible, proved this sary for that purpose. If any, calcareous earth is barren spot to be calcareous, which induced its expresent it will quickly begin to combine with the amination. Four hundred grains yielded eightyacid, throwing off its carbonic acid in gas, which seven of calcareous earth-nearly twenty-two per cannot fail to be observed as it escapes, as the gas cent. This soil was afterwards dug and carried that only eight grains of calcareous earth would out as manure. throw out, would be equal in bulk to a gill measure. 5. Black friable loam, from Indian Fields, on Indeed, the product of only a single grain of cal-York River. The soil was a specimen of a field of careous earth, would be abundantly plain to the considerable extent, mixed throughout with oyster eye of the careful operator, though it might be the shells. Though light and mellow, the soil did not whole amount of gas from two thousand grains of appear to be sandy. Rich, durable, and long unsoil. If no effervescence is seen even after adding der exhausting cultivation. more acid and gently stirring the mixture, then it 1260 grains of soil yielded is absolutely certain that the soil contained not the 168

[merged small][ocr errors][merged small][merged small]

of coarse shelly matter, separated mechanically,

8 finely divided calcareous earth. The remaining solid matter, carefully separated, (by agitation and settling in water,) consisted of 130 grains of fine clay, black with putrescent

matter, and which lost more than one-fourth of its weight by being exposed to a red heat,

white sand, moderately fine,

very fine sand,

875

20

36

lost in the process,

[blocks in formation]

330

94

35

23

500

silicious sand-none very coarse,
impalpable aluminous and silicious
earth,
putrescent vegetable matter-none
coarse or unrotted,
loss.

discussion of other points-nor can they now be explained, and reconciled with my proposition, except through a circuitous and apparently digressive course of reasoning. They have not been kept out of view, nor slurred over, to weaken their force, and are now presented in all their strength. These difficulties will be considered, and removed, in the following chapters.

CHAPTER VI.

CHEMICAL EXAMINATION OF RICH SOILS CON-
TAINING NO CALCAREOUS EARTH.

PROPOSITION 2. Continued.

Under common circumstances, when any disputant admits facts that seem to contradict his own reasoning, such admission is deemed abundant evidence of their existence. But though now placed exactly in this situation, the facts admitted by me are so opposed to all that scientific agriculturists have taught us to expect, that it is necessary for me to show the grounds on which my adIt is unnecessary to cite any particular trials of mission rests. Few would have believed in the our poor soils, as it has been stated in the pre-absence of calcareous earth in all our poor soilsceding chapter that all are entirely destitute of cal- and far more strange is it that the same deficiency careous earth-excluding the rare, but well marked should extend to such rich soils as some that will exceptions of its great excess, of which an example has been given in the soil marked 4, in the foregoing examinations.

Unless then I am mistaken in supposing that these facts are universally true, the certain results of chemical analysis completely establish these general rules-viz:

That all calcareous soils are naturally fertile and durable in a very high degree-and That all soils naturally poor are entirely destitute

of calcareous earth.

It then can scarcely be denied that calcareous earth must be the cause of the fertility of the one class of soils, and that the want of it produces the poverty of the other. Qualities that always thus accompany each other, cannot be otherwise than cause and effect. If further proof is wanting, it can be safely promised to be furnished when the practical application of calcareous manures to poor soils will be treated of, and their effects stated.

These deductions are then established as to all

be cited.

The following specimens, taken from well known and very fertile soils, were found to contain no calcareous earth. Many trials of other rich soils have yielded like results-and indeed, I have never found calcareous earth in any soil below the falls of the rivers, in which, or near which, some particles of shells were not visible.

1. Soil from Eppes' Island, which lies in James River, near City Point; light and friable (but not silicious) brown loam, rich and durable. The surface is not many feet above the highest tides, and like most of the best river lands, this tract seems to have been formed by alluvion many ages ago, but which may be termed recent, when compared to the general formation of the tide-water district.

2. Black silicious loam from the celebrated lands on Back River, near Hampton,

3. Soil from rich land on Pocoson River, York County.

4. Black clay vegetable soil, from a fresh-water tide marsh on James River--formed by the most recent alluvion,

belonging to General J. H. Cocke, of Fluvanna.

The most remarkable facts of the absence of calcareous earth, are to be found in the limestone soils, between the Blue Ridge and Alleghany Mountains, Of these, I will report all that I have examined, and none contained any calcareous earth, unless when the contrary will be stated.*

calcareous soils, and all poor soils-which descriptions comprise nine-tenths of all, This alone would open a wide field for the practical exercise 5. Alluvial soil of first rate fertility above the of the truths we have reached. But still there re-the valuable and extensive body of bottom land falls of James River-dark brown clay loam, from main strong objections and stubborn facts opposed to the complete proof of the proposition now under consideration, and consequently to the theory which that proposition is intended to support. The whole difficulty will be apparent at once when I now proceed to state that nearly all of our best soils, such as are very little if at all inferior in value to the small portion of shelly lands, are as destitute of calcareous earth as the poorest. So far as I have examined, this deficiency is no less general in the richest alluvial lands of the upper country-and, what will be deemed by some as incredible, by far the greater part of the rich limestone soils between the Blue Ridge and Alleghany Mountains are equally destitute of calcareous earth. These facts were not named before, to avoid embarrassing the

*Before the first of these trials was made, I supposed (as probably most other persons do,) that limegree. It is difficult to get rid of this impression enstone soil was necessarily calcareous, and in a high detirely-and it may seen a contradiction in terms to say that a limestone soil is not calcareous. This I cannot avoid: I must take the term limestone soil as cus.

1 to 6. Limestone soils selected in the neighborhood of Lexington, Virginia, by Professor Graham, with the view of enabling me to investigate this subject. All the specimens were from first rate soils, except one, which was from land of inferior value. One of the specimens, Mr. Graham's description stated to be "taken from a piece of land so rocky [with limestone] as to be unfit for "cultivation-at least with the plough. I could "scarcely select a specimen which I would expect "to be more strongly impregnated with calcareous "earth." This specimen, by two separate trials, yielded only one grain of calcareous earth, from one thousand of soil. The other six soils contained none. The same result was obtained from 7. A specimen of alluvial land on North River, near Lexington.

8. Brown loam from the Sweet Spring Valley, remarkable for its extraordinary productiveness and durability. It is of alluvial formation, and before it was drained, must have been often covered and saturated by the Sweet Spring and other mineral waters, which hold lime in solution. The surrounding highland is of limestone soil. Of this specimen, taken from about two hundred yards below the Sweet Spring, from land long cultivated every year, three hundred and sixty grains yielded not a particle of calcareous earth. It contained an unusually large proportion of oxide of iron, though my imperfect means enabled me to separate and collect only eight grains, the process evidently wasting several more.

About a mile lower down, drains were then making (in 1826) to reclaim more of this rich valley from the overflowing waters. Another specimen was taken from the bottom of a ditch just opened, eighteen inches below the surface. It was a black loam, and exhibited to the eye some very diminutive fresh-water shells, (perriwinkles, about one-tenth of an inch in length,) and many of their broken fragments. This gave, from two hundred grains, seventy-four of calcareous earth. But this cannot fairly be placed on the same footing with the other soils, as it had obviously been once the bottom of a stream, or lake, and the collection and deposite of so large and unusual a proportion of calcareous matter, seemed to be of animal formation. Both these specimens were selected at my request by one of our best farmers, and who also furnished a written description of the soils, and their situation.

specimen was part of what was in contact with a mass of limestone.

12. Soil from the western foot of the Warm Spring Mountain, on a gentle slope between the court house and the road, and about one hundred and fifty yards from the Warm Bath. Rich brown loam, containing many small pieces of limestone, but no finely divided calcareous earth.

13. A specimen taken two or three hundred yards from the last, and also at the foot of the mountain. Soil, a rich black loam, full of small fragments of limestone of different sizes, between that of a nutmeg and small shot. The land had never been broken up for cultivation. One thousand grains contained two hundred and forty grains of small stone or gravel, mostly limestone, separated mechanically, and sixty-nine grains of finely divided calcareous earth.

14. Black loamy clay, from the excellent wheat soil adjoining the town of Bedford in Pennsylvania: the specimen taken from beneath and in contact with limestone. One thousand grains yielded less than one grain of calcareous earth.

15. A specimen from within a few yards of the last, but not in contact with limestone, contained no calcareous earth: neither did the red clay subsoil, six inches below the surface.

16. Very similar soil, but much deeper, adjoining the principal street of Bedford-the specimen taken from eighteen inches below the surface, and adjoining a mass of limestone. A very small disengagement of gas indicated the presence of calcareous earth--but certainly less than one grain in one thousand, and perhaps not half that quantity.

17. Alluvial soil on the Juniata, adjoining Bed

ford.

18. Alluvial vegetable soil near the stream flowing from all the Saratoga Mineral Springs, and necessarily often covered and soaked by those waters, and

19. Soil taken from the bed of the same stream neither contained any portion of carbonate of lime.

Thus it appears, that of nineteen specimens of soils, only four contained calcareous earth, and three of these four, in exceedingly small proportions. It should be remarked that all these were selected from situations, which from their proximity to calcareous rock, or exposure to calcareous waters, were supposed most likely to present high9. Woodland, west of Union, Monroe County. ly calcareous soils. If five hundred specimens Soil, a black clay loam, lying on, but not inter- had been taken without choice, from what are mixed at the surface with limestone rock. Sub-commonly limestone soils, (merely because they soil, yellowish clay. The rock at this place, a foot below the surface. Principal growth, sugar maple, white walnut, and oak. This and the next specimen are from one of the richest tracts of highland that I have seen.

10. Soil similar to the last and about two hundred yards distant. Here the limestone showed above the surface, and the specimen was taken from between two large masses of fixed rock, and about a foot distant from each.

11. Black rich soil, from woodland between the Hot and Warm Springs, in Bath County. The

tom has already fixed it. But it should not be extended to any soils except those which are so near to limestone rock, as in some measure to be thereby affected in their qualities and value.

are not very distant from limestone rock, or springs of limestone water,) the analysis of that whole number would be less likely to show calcareous earth, than the foregoing short list. I therefore feel justified, from my own few examinations, and unsupported by any other authority, to pronounce that calcareous earth will very rarely be found in any soils between the falls of our rivers, and the navigable western waters. In a few specimens of some of the best soils from the borders of the Mississippi and its tributary rivers, I found calcareous earth present in all-but in small proportions, and in no case exceeding two per cent.

The only soils of considerable extent of surface which, from the specimens that I have examined, appear to be highly calcareous, and to agree in that respect, with many European soils, are from

the prairies, those lands of the west which, generally small: the soil from four to ten feet whether rich or poor, are remarkable for being deep."* destitute of trees, and covered with grass, so as to form natural meadows. The examinations were made but recently, (in 1834) and are reported because presenting striking exceptions to the general constitution of soils in this country.

20: Prairie soil of the most productive kind in Alabama, is a black clay, with very little sand, yet so far from being stiff, that it becomes too light by cultivation. This kind of land is stated by the friend to whom I am indebted for the specimens, to "produce corn and oats most luxuriantly-and also cotton for two or three years; but after that time cotton is subject to the rust, probably from the then open state of the soil, which by cultivation has by that time become as light and as soft as a bank of ashes." One hundred grains of the specimen contained eight of carbonate of lime. All this prairie land in Alabama lies on a substratum of what is there called "rotten limestone," (specimens of which contained seventy-two to eighty-. two per cent. of lime,) and which rises to the surface sometimes, forming the "bald prairies," a sample of the soil of which (21) contained fifty-nine per cent. of carbonate of lime. This was described as "comparatively poor-neither trees nor bushes grow there, and only grass and weeds before cultivation-corn does not grow well-small grain better-and cotton soon becomes subject to the rust." The excessive proportion of calcareous earth is evidently the cause of its barrenness.

The substratum called limestone is soft enough to be cut easily and smoothly with a knife, and some of it is in appearance and texture more like the chalk of Europe, than any other earth that I have seen in this country.

The foregoing details, respecting limestone lands, may perhaps be considered an unnecessary digression, in a treatise on the soils of the tidewater district. But the analysis of limestone soils furnishes the strongest evidence of the remarkable and novel fact of the general absence of calcareous earth-and the information thence derived, will be used to sustain the following steps of my argument.

All the examinations of soils in this chapter concur in opposing the general application of the proposition that the deficiency of calcareous earth is the cause of the sterility of our soils: and having stated the objection in all its force, I shall now proceed to inquire into its causes, and endeavor to dispel its apparent opposition to my doctrine.

CHAPTER VII.

PROOFS OF THE EXISTENCE

NEUTRAL SOILS.

PROPOSITION 2.

OF ACID AND

Continued.

Sufficient evidence has been adduced to prove that many of our most fertile and valuable soils are destitute of calcareous earth: but it does not necessarily follow that such has always been their comcombined with some other acid than the carbonic. position or that they may not now contain lime That this is really the case, I shall now offer proofs to establish-and not only maintain this position with regard to those valuable soils, but shall convegetable acid, is present in every soil capable of tend that lime in some proportion, combined with

22. A specimen of the very rich "cane brake" lands in Marengo County, Alabama, contained six-supporting vegetation. teen per cent. of carbonate of lime. This is a kind of prairie, of a wetter nature, from the winter rains not being able to run off from the level surface, nor to sink through the tenacious clay soil, and the solid stratum of limestone below.

23. A specimen from the very extensive "Choctaw Prairie" in Mississippi, of celebrated fertility, yielded thirteen per cent. of carbonate of lime.

Several other specimens of different, but all of very fertile soils from Southern Alabama, and all lying over the substratum of soft limestone, were found to be neutral, containing not a particle of lime in the form of carbonate. These specimens were as follows:

24. One from the valley cane land—“very wet through the winter, but always dry in summerand after being ditched, is dry enough to be cultivated in cotton, which will grow from eight to twelve feet high."

But while I shall endeavor to maintain these positions, without asking or admitting any excep tion, let me not be understood as asserting that the original ingredient of calcareous earth was ticular soil, or that a knowledge of the proportion always the sole cause of the fertility of any parcontained, would serve to measure the capacity of differing materially in qualities or value, often exthe soil for improvement. Calcareous soils not hibit a remarkable difference in their respective proportions of calcareous earth: so that it would seem, that a small quantity, aided by some other unknown agent, may give as much capacity for improvement, and ultimately produce as much fer

*It is proper to mention a circumstance which may lime from these Alabama soils, besides the more genehave had some effect in removing the carbonate of ral causes which will be traced in the next chapter.

This mineral

25. Another from what is called the best "post-oak With these specimens of soil, was sent a collection of land," on which trees of that kind grow to the the small stones and gravel which were stated to be size of from two to four feet in diameter-having found generally through these soils, and particularly in but little underwood, and no cane growth-the clay subsoil beneath. Among these there were "thought to be nearly as rich as the best cane several fragments of sulphuret of iron. land, and will produce 1500 lbs. or more, of seed when decomposing in the earth in contact with carbocotton, or fifty bushels of corn to the acre.' nate of lime, also decomposes the latter substance, and forms sulphate of lime, [gypsum,] instead. It is well found in these soils. It may be known by its great worth inquiry whether sulphuret of iron is generally weight, and metallic lustre when broken, (which has caused it often to be mistaken for silver ore,) and by giving out fumes of burning sulphur when subjected to strong heat under a blow pipe.

26. Another from what is termed "palmetto land, having on it that plant as well as a heavy cover of large trees growing luxuriantly. It is a cold and wet soil before being brought into good tilth; but afterwards is soft and easy to till, and produces corn and cotton finely. The cane on it is

« AnteriorContinuar »