Imagens das páginas
PDF
ePub
[merged small][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][graphic][merged small]
[blocks in formation]

4.5

0.5 chiefly oxide of iron.

0.0 | 81.0

1.62

12

6.0

1. 0.5 alumina, 0.5 ox- | 0.5 | 81.0 |

ide of iron.

Iowa soils.
Soil from the west side of Dubuque, from a flat | 3.5

valley.
Southeast quarter of section 25, township 89 north, I

range 2 east of the 5th principal meridian, from

the ridge.
From near Dubuque river bottom, from a corn-field
Average soil from townships 84, 85, 86, 87, range 3 4.3

west of the 5th principal meridian.
Township 81 norih, range 2 east of the 5th princi- 1.5

pal meridian.

6.5 3.5~1.3 lime, 0.3 mag:

nesia, 0.8 oxide of

iron.
5.0 2.5-1.8 lime, 0.2 mag-

nesia, 0.5 oxide of

iron.
4.0 | 2.5 lime, magnesia, and

a little oxide of iron.
1.5 chiefly alumina.
1.0 chiefly lime.

3.0

1.

6.0

3.0

[blocks in formation]

Average of 15 specimens

3.6

4.8 / 5.13

82.5

1.84

Note. -The saline matter insoluble in water, but soluble in muriatic acid, of soils Nos. 9 and 14, was tested for phosphoric acid, by fusing with carbonate
of soda, dissolving with acetic acid, and adding nitrate of silver. No sulphur-yellow precipitate appeared indicative of phosphoric acid. Indeed, muriatic,
a trace of sulphuric and carbonic acids, were the only inorganic acids which could be detected in combination with the saline bases, Oxide of iron appeared
in most cases the chief constituent of the saline mauer insoluble in water. These virgin soils seem, therefore, to contain lille or no phosphates.

plants—the nic matter of the from the above

To a correct appreciation of the results obtained from the above table, it may be remarked, that the organic matter of the soil (sometimes called geine)—the food of plants—the substance, which, by the action of air and water, has been prepared, or is in course of preparation, to enter into the circulation of the plant,-is that portion of the soil which chiefly communicates to it its prolific qualities; and that, all other things being equal, a soil may be expected to be productive, in proportion to the amount of organic matter it contains.*

This organic matter is in part soluble, and in part insoluble, in alkali. "The soluble portion of it is supposed, with much plausibility, to be that which is already prepared to become nutriment for plants; the insoluble portion is regarded as that which, by the action of air and moisture, and other influences, will hereafter become so.

If this theory be an accurate one, it follows that those soils which contain a large proportion of soluble organic matter will be fertile for the time; but that they must also contain a good supply of insoluble geine to preserve their fertility. And thus the column of soluble organic matter in the table is that which measures the present productiveness, and that of insoluble organic matter that which indicates the durability of the soil.

The salts which enter into the composition of a soil are considered by agricultural chemists as its stimulating ingredient. Chaptal, in his “ Che.. mistry applied to Agriculture,” says, (a little fancifully, perhaps,) “ The salts : are to plants, what spices and marine salts are to man.”+ It is certain that the salts in any soil exert upon the organic matter a chemical action, and contribute to regulate and facilitate the process of nutrition. Without an adequate supply of saline material, then, a soil lacks one of the essential ingredients of fecundity.

To form an estimate, from the above table, of the quality of the Wiskonsin soils, it is necessary to compare its results with similar results obtained in countries in which, by actual culture, the value of the soil has, to some extent, been proved. The difficulty here is, that such analyses of soils have very rarely been made or recorded. Professor Hitchcock, in his Re-port, of the year 18:38, on the Economical Geology of Massachusetts, furnishes a valuable table of this kind, exhibiting the analyses of one hundred and twenty-five specimens, which, as he informs us, may be considered as about the average quality of the soils of that State. He adds: “ As this is probably the first attempt that has been made to obtain the amount of geine in any considerable number of soils, we cannot compare the results with those obtained in other places. They will be convenient, however, for comparison with future analyses."

And they do accordingly furnish data for a comparison, both interesting and important, between the soil of Massachusetts and that of Wiskonsin.

The following are the results obtained from Professor Hitchcock's table: Average quantity of soluble gcinc (organic matter) - - 3.90 per cent. Average quantity of insoluble geine (organic matter) - 3.70 " Average specific gravity of soil • - - - - 2.44 "

My own table, as will have been remarked, shows the results for the soils of Iowa and Wiskonsin to be

An exception to this rule, which should not be overlooked, exists in the case of bog or peat soils; which, however, possess in general bui liile soluble organic matter.

t Dr. Dana i nproves on this idea. He says: "The earihs are the plates, the salts the sea. soning, and the geine the food of plants.”

Average quantity of soluble organic matter - - - 4.80 per cent. Average quantity of insoluble organic matter ..

. 5.13 " Average specific gravity of soil . .

• 1.84. « The first result which strikes the eye is the large amount of organic matter in the lowa and Wiskonsin soils, compared with those of Massachusetts-nearly one third greater.

The second is the great specific gravity of the Massachusetts soils, compared with those of Iowa and Wiskonsin--nearly one-third greater.

A more careful inspection shows that the amount of organic matter is, almost to mathematical accuracy, in the inverse ratio of the specific grasity of the soils.

Il would be a hasty inference thence to deduce the conclusion that soils are rich in geine, in proportion to their specific lightness; yet the coincidence, in this respect, is marked and worthy of attention.

It will be seen, for instance, that specimen No. 6, the richest valley soil, contaiping the enormous quantity of twenty six per cent. of organic matter, is considerably lighter than any other specimen, and is only about one-half the weight of the average soil of the entire State of Massachusetts; while the specimen No. 10, heavier than any single soil among the 125 examined by Prolessor Hitchcock, (specific gravity 2.82, has but one per cent. of organic matter ; much less than any other specimen in the table.

In Professor Hitchcock's table, specimen 120 is the lightest, having a specific gravity of 2.17. This soil gave nearly thirteen per cent. of geinealmost double the average of the entire table; while the two heaviest specimens in the whole number, Nos. 20 and 21, (specific gravity 2.72 and 2.71.) had no geine whatever ; and these are the only two specimens out of the one hundred and twenty-five thus totally devoid of organic matter.

In addition to this, there is throughout Professor Hitchcock's table (as it will be perceived there is also in inine) a general coincidence between a small specific gravity and a large quantity of organic matter.

If further analysis of soils in various portions of this and other countries should exbilit similar results, it would appear that a simple trial of the specific gravity of a soil may, in a general way, turnish an approximating test of its fertility.

Be this as it may, the dark mould which prevails over a large proportion of lowa and Wiskonsin, so rich in geine, and of so small specific gravity, has proved itself, wherever the farmer has trusted to its certain relurns, instead of attempting the more hazardous venture of the mine, an excellent and productive soil; especially adapted to the culture of every species os culi.

nary vegetables and small grain, and producing, probably, as good Indian · corn as the State of New York, or any other State of the same latitude.

It will be observed, from the table, that the power of absorption is gen· erally in proportion to the amount of geine and the lightness of the soil.* ! This is an important item to the cultivator. Lands possessing this power in a considerable degree readily absorb the dew in dry weather; and, in wet weather, do not suffer the superfluous rain to accumulate on the surface.

A striking feature in the character of the Iowa and Wiskonsin soils, as the table shows, is the entire absence, in most of the specimens, of clay,

*"In general, the more finely the parts of a soil are divided, the better they absorb esder."- Chaptal.'

This applies particularly, as the sequel will show, to the soils in question.

and the large proportion of silex. This silex, however, does not commonly show itself here in its usual form--that of a quartzose sand. It appears as a fine, almost impalpable, siliceous powder, frequently occurring

in concreted lumps that resemble clay; and, indeed, it was often reported # to me incorrectly as clay-an error ultimately detected by analysis.

This almost impalpable powder, the chief constituent and almost sole 9 residuum of the Iowa and Wiskonsin soils, is so highly comminuted, that,

when examined under the microscope, for the most part, its atoms present

no chrystalline or even granular appearance. i This fine siliceous residuum, after being boiled with strong aqua regia, lost but 10 per cent. ; of which but 5 per cent. was alumina.

This absence of any material percentage of clay in the soils under conEsideration prevents the rolling lands from washing away; and it imparts

to the streams a chrystal clearness, which even after heavy rains is hardly disturbed. The appearance of these transparent rivulets flowing over a soil, which when moistened by rain is often of an inky blackness, arrests, by its singularity, the eye of a stranger.

Whether the lack of clay in the Iowa and Wiskonsin soils will render them less durable, may be doubted. A coarse sandy soil, the open pores of which suffer the rain to percolate, carrying with it the nutritive geine from the surface, requires an admixture of clay before it can become rich and durable; but the minute-grained siliceous powder of this district forms a species of soil entirely different from the above-one which, without any such admixture, retains moisture and geine in much perfection.

I believe it to be peculiarly adapted to the growth of the sugar-beet, which flourishes best in a loose fertile mould, and which has of late become, in some European countries, an important article of commerce. It is estimated that the amount of beet-sugar manufactured in France during the last year was 100,000,000 pounds, and in Prussia and Germany 30,000,000 pounds. In the western part of Michigan, in as northern a

latitude, and in a climate similar to that of Wiskonsin, 240,000 pounds are F reported by the papers of that State (how accurately I know not) to have been manufactured during last season.

In concluding this brief notice of the soils of this district, which I regret that time does not permit me to extend, I may add, that I know of no country in the world, with similar mineral resources, which can lay claim to a soil as fertile and as well adapted to the essential purposes of agriculture.

DOCTOR LOCKE'S REPORT.

. In the report made to me by Doctor Locke, and which is herewith forwarded, will be found a variety of interesting and useful matter.

As that gentleman, while acting as one of the geological corps of Ohio, had spent nearly an entire scason in examining those counties in that State where the cliff formation is most marked and most readily studied, I intrusted to him the care of instituting a comparison between the corresponding formations in Ohio, and in lowa and Wiskonsin. This he has executed with his usual ability; and it will be found an important contribution to the geology of Wiskonsin and of the west.

Of the practical importance of the barometrical observations of heights, whence the dip and thickness of the various strata are determined, I have already spoken in detail.

« AnteriorContinuar »