Chapter VI: Part II (1)

ON THE AGRICULTURAL USES OF PEAT AND SWAMP MUCK.

After the foregoing account of the composition of peat, we may proceed to notice:

1.--_The characters that adapt it for agricultural uses._

These characters are conveniently discussed under two heads, viz.:

Those which render it useful in improving the texture and physical characters of the soil, and indirectly contribute to the nourishment of crops,--characters which constitute it an _amendment_ to the soil (_A_); and

Those which make it a direct _fertilizer_ (_B_).

A.--Considered as an amendment, the value of peat depends upon

_Its remarkable power of absorbing and retaining water, both as a liquid and as a vapor_ (I):

_Its power of absorbing ammonia_ (II):

_Its effect in promoting the disintegration and solution of mineral ingredients, that is the stony matters of the soil_ (III): _and_

_Its influence on the temperature of the soil_ (IV).

The agricultural importance of these properties of peat is best illustrated by considering the faults of a certain class of soils.

Throughout the State of Connecticut, for instance, are found abundant examples of light, leachy, hungry soils, which consist of coarse sand or fine gravel; are surface-dry in a few hours after the heaviest rains, and in the summer drouths, are as dry as an ash-heap to a depth of several or many feet.

These soils are easy to work, are ready for the plow early in the spring, and if well manured give fair crops in wet seasons. In a dry summer, however, they yield poorly, or fail of crops entirely; and, at the best, they require constant and very heavy manuring to keep them in heart.

Crops fail on these soils from two causes, viz.; _want of moisture_ and _want of food_. Cultivated plants demand as an indispensable condition of their growth and perfection, to be supplied with water in certain quantities, which differ with different crops. Buckwheat will flourish best on dry soils, while cranberries and rice grow in swamps.

Our ordinary cereal, root, forage and garden crops require a medium degree of moisture, and with us it is in all cases desirable that the soil be equally protected from excess of water and from drouth. Soils must be thus situated either naturally, or as the result of improvement, before any steadily good results can be obtained in their cultivation. The remedy for excess of water in too heavy soils, is thorough drainage. It is expensive, but effectual. It makes the earth more porous, opens and maintains channels, through which the surplus water speedily runs off, and permits the roots of crops to go down to a considerable depth.

What, let us consider, is the means of obviating the defects of soils that are naturally too porous, from which the water runs off too readily, and whose crops "burn up" in dry seasons?

In wet summers, these light soils, as we have remarked, are quite productive if well manured. It is then plain that if we could add anything to them which would retain the moisture of dews and rains in spite of the summer-heats, our crops would be uniformly fair, provided the supply of manure were kept up.

But why is it that light soils, need more manure than loamy or heavy lands? We answer--because, in the first place the rains which quickly descend through the open soil, wash down out of the reach of vegetation the soluble fertilizing matters, especially the nitrates, for which the soil has no retentive power; and in the second place, from the porosity of the soil, the air has too great access, so that the vegetable and animal matters of manures decay too rapidly, their volatile portions, ammonia and carbonic acid, escape into the atmosphere, and are in measure lost to the crops. From these combined causes we find that a heavy dressing of well-rotted stable manure, almost if not entirely, disappears from such soils in one season, so that another year the field requires a renewed application; while on loamy soils the same amount of manure would have lasted several years, and produced each year a better effect.

We want then to _amend_ light soils by incorporating with them something that prevents the rains from leaching through them too rapidly, and also that renders them less open to the air, or absorbs and retains for the use of crops the volatile products of the decay of manures.

For these purposes, vegetable matter of some sort is the best and almost the only amendment that can be economically employed. In many cases a good peat or muck is the best form of this material, that lies at the farmer's command.

I.--_Its absorbent power for liquid water_ is well known to every farmer who has thrown it up in a pile to season for use. It holds the water like a sponge, and, according to its greater or less porosity, will retain from 50 to 100 or more _per cent._ of its weight of liquid, without dripping. Nor can this water escape from it rapidly. It dries almost as slowly as clay, and a heap of it that has been exposed to sun and wind for a whole summer, though it has of course lost much water, is still distinctly wet to the eye and the feel a little below the surface.

_Its absorbent power for vapor of water_ is so great that more than once it has happened in Germany, that barns or close sheds filled with partially dried peat, such as is used for fuel, have been burst by the swelling of the peat in damp weather, occasioned by the absorption of moisture from the air. This power is further shown by the fact that when peat has been kept all summer long in a warm room, thinly spread out to the air, and has become like dry snuff to the feel, it still contains from 8 to 30 _per cent._ (average 15 _per cent._) of water. To dry a peat thoroughly, it requires to be exposed for some time to the temperature of boiling water. It is thus plain, as experience has repeatedly demonstrated, that no ordinary summer heats can dry up a soil which has had a good dressing of this material, for on the one hand, it soaks up and holds the rains that fall upon it, and on the other, it absorbs the vapor of water out of the atmosphere whenever it is moist, as at night and in cloudy weather.

When peat has once become _air-dry_, it no longer manifests this avidity for water. In drying it shrinks, loses its porosity and requires long soaking to saturate it again. In the soil, however, it rarely becomes air-dry, unless indeed, this may happen during long drouth with a peaty soil, such as results from the draining of a bog.

II.--_Absorbent power for ammonia._

All soils that deserve to be called fertile, have the property of absorbing and retaining ammonia and the volatile matters which escape from fermenting manures, but light and coarse soils may be deficient in this power. Here again in respect to its absorptive power for ammonia, peat comes to our aid.

It is easy to show by direct experiment that peat absorbs and combines with ammonia.

In 1858 I took a weighed quantity of air-dry peat from the New Haven Beaver Pond, (a specimen furnished me by Chauncey Goodyear, Esq.,) and poured upon it a known quantity of dilute solution of ammonia, and agitated the two together occasionally during 48 hours. I then distilled off at a boiling heat the unabsorbed ammonia and determined its quantity. This amount subtracted from that of the ammonia originally employed, gave the quantity of ammonia absorbed and retained by the peat at the temperature of boiling water.

The peat retained ammonia to the amount of 0.95 of _one per cent._

I made another trial at the same time with carbonate of ammonia, adding excess of solution of this salt to a quantity of peat, and exposing it to the heat of boiling water, until no smell of ammonia was perceptible. The entire nitrogen in the peat was then determined, and it was found that the dry peat which originally contained nitrogen equivalent to 2.4 _per cent._ of ammonia, now yielded an amount corresponding to 3.7 _per cent._ The quantity of ammonia absorbed and retained at a temperature of 212 deg., was thus 1.3 _per cent._

This last experiment most nearly represents the true power of absorption; because, in fermenting manures, ammonia mostly occurs in the form of carbonate, and this is more largely retained than free ammonia, on account of its power of decomposing the humate of lime, forming with it carbonate of lime and humate of ammonia.

The absorbent power of peat is well shown by the analyses of three specimens, sent me in 1858, by Edwin Hoyt, Esq., of New Canaan, Conn. The first of these was the swamp muck he employed. It contained in the air-dry state nitrogen equivalent to 0.58 _per cent._ of ammonia. The second sample was the same muck that had lain under the flooring of the horse stables, and had been, in this way, partially saturated with urine. It contained nitrogen equivalent to 1.15 _per cent._ of ammonia. The third sample was, finally, the same muck composted with white-fish. It contained nitrogen corresponding to 1.31 _per cent._ of ammonia.[3]

The quantities of ammonia thus absorbed, both in the laboratory and field experiments are small--from 0.7 to 1.3 _per cent._ The absorption is without doubt chiefly due to the organic matter of the peats, and in all the specimens on which these trials were made, the proportion of inorganic matter is large. The results therefore become a better expression of the power of _peat_, in general, to absorb ammonia, if we reckon them on the organic matter alone. Calculated in this way, the organic matter of the Beaver Pond peat (which constitutes but 68 _per cent._ of the dry peat) absorbs 1.4 _per cent._ of free ammonia, and 1.9 _per cent._ of ammonia out of the carbonate of ammonia.

Similar experiments, by Anderson, on a Scotch peat, showed it to possess, when wet, an absorptive power of 2 _per cent._, and, after drying in the air, it still retained 1.5 _per cent._--[Trans. Highland and Ag'l Soc'y.]

When we consider how small an ingredient of most manures nitrogen is, viz.: from one-half to three-quarters of one _per cent._ in case of stable manure, and how little of it, in the shape of guano for instance, is usually applied to crops--not more than 40 to 60 lbs. to the acre, (the usual dressings with guano are from 250 to 400 lbs. per acre, and nitrogen averages but 15 _per cent._ of the guano), we at once perceive that an absorptive power of one or even one-half _per cent._ is greatly more than adequate for every agricultural purpose.

III.--_Peat promotes the disintegration of the soil._

The soil is a storehouse of food for crops; the stores it contains are, however, only partly available for immediate use. In fact, by far the larger share is locked up, as it were, in insoluble combinations, and only by a slow and gradual change can it become accessible to the plant. This change is largely brought about by the united action of _water_ and _carbonic acid gas_. Nearly all the rocks and minerals out of which fertile soils are formed,--which therefore contain those inorganic matters that are essential to vegetable growth,--though very slowly acted on by pure water, are decomposed and dissolved to a much greater extent by water, charged with carbonic acid gas.

It is by these solvents that the formation of soil from broken rocks is to a great extent due. Clay is invariably a result of their direct action upon rocks. The efficiency of the soil depends greatly upon their chemical influence.

_The only abundant source of carbonic acid in the soil, is decaying vegetable matter._

Hungry, leachy soils, from their deficiency of vegetable matter and of moisture, do not adequately yield their own native resources to the support of crops, because the conditions for converting their fixed into floating capital are wanting. Such soils dressed with peat or green manured, at once acquire the power of retaining water, and keep that water ever charged with carbonic acid: thus not only the extraneous manures which the farmer applies are fully economized; but the soil becomes more productive from its own stores of fertility which now begin to be unlocked and available.

Dr. Peters, of Saxony, has made some instructive experiments that are here in point. He filled several large glass jars, (2-1/2 feet high and 5-1/2 inches wide) with a rather poor loamy sand, containing considerable humus, and planted in each one, June 14, 1857, an equal number of seeds of oats and peas. Jar No. 2 had daily passed into it through a tube, adapted to the bottom, about 3-1/4 pints of common air. No. 3 received daily the same bulk of a mixture of air and carbonic acid gas, of which the latter amounted to one-fourth. No. 1 remained without any treatment of this kind, _i. e._: in just the condition of the soil in an open field, having no air in its pores, save that penetrating it from the atmosphere. On October 3, the plants were removed from the soil, and after drying at the boiling point of water, were weighed. The crops from the pots into which air and carbonic acid were daily forced, were about _twice as heavy_ as No. 1, which remained in the ordinary condition.

Examination of the soil further demonstrated, that in the last two soils, a considerably greater quantity of mineral and organic matters had become soluble in water, than in the soil that was not artificially aerated. The actual results are given in the table below in grammes, and refer to 6000 grammes of soil in each case:--

ACTION OF CARBONIC ACID ON THE SOIL. -----------------------------------+-----------+--------+------------ | _No. 1, | | | Without |_No. 2, | _No. 3, _Substances soluble in water, etc._| Artificial| Common | Air and | Supply of | Air | Carbonic | Air._ | Added._|acid added._ -----------------------------------+-----------+--------+------------ Mineral matters | 2.04 | 3.71 | 4.99 Potash | 0.07 | 0.17 | 0.14 Soda | 0.17 | 0.23 | 0.28 Organic matters | 2.76 | 4.32 | 2.43 | | | Weight of Crops | 5.89 | 10.49 | 12.35 -----------------------------------+-----------+--------+------------

It will be seen from the above that air alone exercised nearly as much solvent effect as the mixture of air with one-fourth its weight of carbonic acid; this is doubtless, in part due to the fact that the air, upon entering the soil rich in humus, caused the abundant formation of carbonic acid, as will be presently shown must have been the case. It is, however, probable that organic acids (crenic and apocrenic,) and nitric acid were also produced (by oxidation,) and shared with carbonic the work of solution.

It is almost certain, that the acids of peat exert a powerful decomposing, and ultimately solvent effect on the minerals of the soil; but on this point we have no precise information, and must therefore be content merely to present the probability. This is sustained by the fact that the crenic, apocrenic and humic acids, though often partly uncombined, are never wholly so, but usually occur united in part to various bases, viz.: lime, magnesia, ammonia, potash, alumina and oxide of iron.

The crenic and apocrenic acids (that are formed by the oxidation of ulmic and humic acids,) have such decided acid characters,--crenic acid especially, which has a strongly sour taste--that we cannot well doubt their dissolving action.

IV.--_The influence of peat on the temperature_ of light soils dressed with it may often be of considerable practical importance. A light dry soil is subject to great variations of temperature, and rapidly follows the changes of the atmosphere from cold to hot, and from hot to cold. In the summer noon a sandy soil becomes so warm as to be hardly endurable to the feel, and again it is on such soils that the earliest frosts take effect. If a soil thus subject to extremes of temperature have a dressing of peat, it will on the one hand not become so warm in the hot day, and on the other hand it will not cool so rapidly, nor so much in the night; its temperature will be rendered more uniform, and on the whole, more conducive to the welfare of vegetation. This regulative effect on temperature is partly due to the stores of water held by peat. In a hot day this water is constantly evaporating, and this, as all know, is a cooling process. At night the peat absorbs vapor of water from the air, and condenses it within its pores, this condensation is again accompanied with the evolution of heat.

It appears to be a general, though not invariable fact, that dark colored soils, other things being equal, are constantly the warmest, or at any rate maintain the temperature most favorable to vegetation. It has been repeatedly observed that on light-colored soils plants mature more rapidly, if the earth be thinly covered with a coating of some black substance. Thus Lampadius, Professor in the School of Mines at Freiberg, a town situated in a mountainous part of Saxony, found that he could ripen melons, even in the coolest summers, by strewing a coating of coal-dust an inch deep over the surface of the soil. In some of the vineyards of the Rhine, the powder of a black slate is employed to hasten the ripening of the grape.

Girardin, an eminent French agriculturist, in a series of experiments on the cultivation of potatoes, found that the time of their ripening varied eight to fourteen days, according to the character of the soil. He found, on the 25th of August, in a very dark soil, made so by the presence of much humus or decaying vegetable matter, twenty-six varieties ripe; in sandy soil but twenty, in clay nineteen, and in a white lime soil only sixteen.

It cannot be doubted then, that the effect of dressing a light sandy or gravelly soil with peat, or otherwise enriching it in vegetable matter, is to render it warmer, in the sense in which that word is usually applied to soils. The upward range of the thermometer is not, indeed, increased, but the uniform warmth so salutary to our most valued crops is thereby secured.

In the light soils stable-manure wastes too rapidly because, for one reason, at the extremes of high temperature, oxidation and decay proceed with great rapidity, and the volatile portions of the fertilizer are used up faster than the plant can appropriate them, so that not only are they wasted during the early periods of growth, but they are wanting at a later period when their absence may prove the failure of a crop.

B. The ingredients and qualities which make peat _a direct fertilizer_ next come under discussion. We shall notice:

_The organic matters including nitrogen (ammonia and nitric acid)_ (I):

_The inorganic or mineral ingredients_ (II):

_Peculiarities in the decay of Peat_ (III), _and_

_Institute a comparison between peat and stable manure_ (IV).

I.--Under this division we have to consider:

1. _The organic matters as direct food to plants._

Thirty years ago, when Chemistry and Vegetable Physiology began to be applied to Agriculture, the opinion was firmly held among scientific men, that the organic parts of humus--by which we understand decayed vegetable matter, such as is found to a greater or less extent in all good soils, and _abounds_ in many fertile ones, such as constitutes the leaf-mold of forests, such as is produced in the fermenting of stable manure, and that forms the principal part of swamp-muck and peat,--are the true nourishment of vegetation, at any rate of the higher orders of plants, those which supply food to man and to domestic animals.

In 1840, Liebig, in his celebrated treatise on the "Applications of Chemistry to Agriculture and Physiology," gave as his opinion that these organic bodies do not nourish vegetation except by the products of their decay. He asserted that they cannot enter the plant directly, but that the water, carbonic acid and ammonia resulting from their decay, are the substances actually imbibed by plants, and from these alone is built up the organic or combustible part of vegetation.

To this day there is a division of opinion among scientific men on this subject, some adopting the views of Liebig, others maintaining that certain soluble organic matters, viz., crenic and apocrenic acids are proper food of plants.

On the one hand it has been abundantly demonstrated that these organic matters are not at all essential to the growth of agricultural plants, and can constitute but a small part of the actual food of vegetation taken in the aggregate.

On the other hand, we are acquainted with no satisfactory evidence that the soluble organic matters of the soil and of peat, especially the crenates and apocrenates, are not actually appropriated by, and, so far as they go, are not directly serviceable as food to plants.

Be this as it may, practice has abundantly demonstrated the value of humus as an ingredient of the soil, and if not directly, yet indirectly, it furnishes the material out of which plants build up their parts.

2. _The organic matters of peat as indirect food to plants._ Very nearly one-half, by weight, of our common crops, when perfectly dry, consists of _carbon_. The substance which supplies this element to plants is the gas, carbonic acid. Plants derive this gas mostly from the atmosphere, absorbing it by means of their leaves. But the free atmosphere, at only a little space above the soil, contains on the average but 1/2500 of its bulk of this gas, whereas plants flourish in air containing a larger quantity, and, in fact, their other wants being supplied, they grow better as the quantity is increased to 1/12 the bulk of the air. These considerations make sufficiently obvious how important it is that the soil have in itself a constant and abundant source of carbonic acid gas. As before said, _organic matter, in a state of decay_, is the single material which the farmer can incorporate with his soil in order to make the latter a supply of this most indispensable form of plant-food.

When organic matters decay in the soil, their carbon ultimately assumes the form of Carbonic acid. This gas, constantly exhaling from the soil, is taken up by the foliage of the crops, and to some extent is absorbed likewise by their roots.

Boussingault & Lewy have examined the air inclosed in the interstices of various soils, and invariably found it much richer (10 to 400 times) than that of the atmosphere above. Here follow some of their results:

CARBONIC ACID IN SOILS. -------------------------------------------------------------------------- Key: A - _Volumes of Carbonic acid in 100 of air in pores of Soil._ B - _Cubic feet of air in acre to depth of 14 inches._ C - _Cubic feet of Carbonic acid in acre to depth of 14 inches._ D - _Volumes of Carbonic acid to 100 of air above the soil._ E - _Cubic feet of air over one acre to height of 14 inches._ F - _Cubic feet of Carbonic acid over one acre to a height of 14 inches._

--------------------------------------------------------+-----+------+---- _Designation and Condition of Soil._ | A | B | C --------------------------------------------------------+-----+------+---- Sandy subsoil of forest |0.24 | 4,326| 14 Loamy " " " |0.82 | 3,458| 28 Surface soil " " |0.86 | 5,768| 56 Clayey soil of artichoke field |0.66 |10,094| 71 Soil of asparagus bed, unmanured for one year |0.79 |10,948| 86 " " " " newly manured |1.54 |10,948| 172 Sandy soil, six days after manuring, and three | | | days of rain.|2.21 |11,536| 257 " " ten " " " " " | | | " " " |9.74 |11,536|1144 Compost of vegetable mold |3.64 |20,608| 772 | | | _Carbonic Acid in Atmosphere_ | D | E | F |-----+------+---- |0.025|50,820| 14 --------------------------------------------------------+-----+------+----

From the above it is seen that in soils containing little decomposing organic matters--as the forest sub-soils--the quantity of carbonic acid is no greater than that contained in an equal bulk of the atmosphere. It is greater in loamy and clayey soils; but is still small. In the artichoke field (probably light soil not lately manured), and even in an asparagus bed unmanured for one year, the amount of carbonic acid is not greatly larger. In newly manured fields, and especially in a vegetable compost, the quantity is vastly greater.

The organic matters which come from manures, or from the roots and other residues of crops, are the source of the carbonic acid of the soil. These matters continually waste in yielding this gas, and must be supplied anew. Boussingault found that the rich soil of his kitchen garden (near Strasburg) which had been heavily manured from the barn-yard for many years, lost one-third of its carbon by exposure to the air for three months (July, August and September,) being daily watered. It originally contained 2.43 _per cent._ At the conclusion of the experiment it contained but 1.60 _per cent._, having lost 0.83 _per cent._

Peat and swamp-muck, when properly prepared, furnish carbonic acid in large quantities during their slow oxidation in the soil.

3. _The Nitrogen of Peat, including Ammonia and Nitric Acid._

The sources of the nitrogen of plants, and the real cause of the value of nitrogenous fertilizers, are topics that have excited more discussion than any other points in Agricultural Chemistry. This is the result of two circumstances. One is the obscurity in which some parts of the subject have rested; the other is the immense practical and commercial importance of this element, as a characteristic and essential ingredient of the most precious fertilizers. It is a rule that the most valuable manures, _commercially considered_, are those containing the most nitrogen. Peruvian guano, sulphate of ammonia, soda-saltpeter, fish and flesh manures, bones and urine, cost the farmer more money per ton than any other manures he buys or makes, superphosphate of lime excepted, and this does not find sale, for general purposes, unless it contains several _per cent._ of nitrogen. These are, in the highest sense, nitrogenous fertilizers, and, if deprived of their nitrogen, they would lose the greater share of their fertilizing power.

The importance of the nitrogen of manures depends upon the fact that those forms (compounds) of nitrogen which are capable of supplying it to vegetation are comparatively scarce.

It has long been known that peat contains a considerable quantity of nitrogen. The average amount in thirty specimens, analyzed under the author's direction, including peats and swamp mucks of all grades of quality, is equivalent to 1-1/2 _per cent._ of the air-dried substance, or more than thrice as much as exists in ordinary stable or yard manure. In several peats the amount is as high as 2.4 _per cent._, and in one case 2.9 _per cent._ were found.

Of these thirty samples, one-half were largely mixed with soil, and contained from 15 to 60 _per cent._ of mineral matters.

Reducing them to an average of 15 _per cent._ of water and 5 _per cent._ of ash, they contain 2.1 _per cent._ of nitrogen, while the organic part, considered free from water and mineral substances, contains on the average 2.6 _per cent._ See table, page 90.

The five peats, analyzed by Websky and Chevandier, as cited on page 24, considered free from water and ash, contain an average of 1.8 _per cent._ of nitrogen.

We should not neglect to notice that peat is often comparatively poor in nitrogen. Of the specimens, examined in the Yale Analytical Laboratory, several contained but half a _per cent._ or less. So in the analyses of Websky, one sample contained but 0.77 _per cent._ of the element in question.

As concerns the state of combination in which nitrogen exists in peat, there is a difference of opinion. Mulder regards it as chiefly occurring in the form of _ammonia_ (a compound of nitrogen and hydrogen), united to the organic acids from which it is very difficult to separate it. Recent investigations indicate that in general, peat contains but a small proportion of ready-formed ammonia.

The great part of the nitrogen of peat exists in an insoluble and inert form: but, by the action of the atmosphere upon it, especially when mixed with and divided by the soil, it gradually becomes available to vegetation to as great an extent as the nitrogen of ordinary fertilizers.

It appears from late examinations that weathered peat may contain _nitric acid_ (compound of nitrogen with oxygen) in a proportion which, though small, is yet of great importance, agriculturally speaking. What analytical data we possess are subjoined.

PROPORTIONS OF NITROGEN, ETC., IN PEAT. ---------+-------------+------------+------------+---------+------------ | | | Total |Ammonia, | | | Analyst. | Nitrogen. |per cent.|Nitric acid. ---------+-------------+------------+------------+---------+------------ 1--Brown | | | | | Peat|Air dry (?) |Boussingault| 2.20 | 0.018 | 0.000 2--Black | | | | | Peat| " | " |Undetermined| 0.025 |Undetermined 3--Peat |Dried at 212 deg.|Reichardt[4]| " | 0.152 | 0.483 4--Peat | " | " | " | 0.165 | 0.525 5--Peat | " | " | " | 0.305 | 0.241 6--Peat | " | " | " | 0.335 | 0.421 ---------+-------------+------------+------------+---------+------------

Specimens 3, 4 and 5, are swamp (or heath) mucks, and have been weathered for use in flower-culture. 3 and 4 are alike, save that 3 has been weathered a year longer than 4. They contain respectively 41, 56 and 67 _per cent._ of organic matter.

Sample 6, containing 86 _per cent._ of organic matter, is employed as a manure with great advantage, and probably was weathered before analysis. It contained 85 _per cent._ of organic substance.

More important to us than the circumstance that this peat contains but little or no ammonia or nitric acid, and the other contains such or such a fraction of one _per cent._ of these bodies, is the grand fact that all peats may yield a good share of their nitrogen to the support of crops, when properly treated and applied.

Under the influence of Liebig's teachings, which were logically based upon the best data at the disposal of this distinguished philosopher when he wrote 25 years ago, it has been believed that the nitrogen of a fertilizer, in order to be available, must be converted into ammonia and presented in that shape to the plant. It has been recently made clear that nitric acid, rather than ammonia, is the form of nitrogenous food which is most serviceable to vegetation, and the one which is most abundantly supplied by the air and soil. The value of ammonia is however positive, and not to be overlooked.

When peat, properly prepared by weathering or composting, is suitably incorporated with a poor or light soil, it slowly suffers decomposition and wastes away. If it be wet, and air have access in limited quantity, especially if _lime_ be mixed with it, a portion of its nitrogen is gradually converted into ammonia. With full access of air _nitric acid_ is produced. In either case, it appears that a considerable share of the nitrogen escapes in the free state as gas, thereby becoming useless to vegetation until it shall have become converted again into ammonia or nitric acid. It happens in a cultivated soil that the oxygen of the air is in excess at the surface, and less abundant as we go down until we get below organic matters: it happens that one day it is saturated with water more or less, and another day it is dry, so that at one time we have the conditions for the formation of ammonia, and at another, those favorable to producing nitric acid. In this way, so far as our present knowledge warrants us to affirm, organic matters, decaying in the soil, continuously yield portions of their nitrogen in the forms of ammonia and nitric acid for the nourishment of plants.

The farmer who skillfully employs as a fertilizer a peat containing a good proportion of nitrogen, may thus expect to get from it results similar to what would come from the corresponding quantity of nitrogen in guano or stable manure.

But the capacity of peat for feeding crops with, nitrogen appears not to stop here. Under certain conditions, _the free nitrogen of the air which cannot be directly appropriated by vegetation, is oxidized in the pores of the soil to nitric acid, and thus, free of expense to the farmer, his crops are daily dressed with the most precious of all fertilizers_.

This gathering of useless nitrogen from the air, and making it over into plant-food cannot go on in a soil destitute of organic matter, requires in fact that vegetable remains or humified substances of some sort be present there. The evidence of this statement, whose truth was maintained years ago as a matter of opinion by many of the older chemists, has recently become nearly a matter of demonstration by the investigations of Boussingault and Knop, while the explanation of it is furnished by the researches of Schoenbein and Zabelin. To attempt any elucidation of it here would require more space than is at our disposal.

It is plain from the contents of this paragraph that peat or swamp muck is, in general, an abundant source of nitrogen, and is often therefore an extremely cheap means of replacing the most rare and costly fertilizers.

II.--With regard to the _inorganic matters of peat_ considered as food to plants, it is obvious, that, leaving out of the account for the present, some exceptional cases, they are useful as far as they go.

In the ashes of peats, we almost always find small quantities of sulphate of lime, magnesia and phosphoric acid. Potash and soda too, are often present, though rarely to any considerable amount. Carbonate and sulphate of lime are large ingredients of the ashes of about one-half, of the thirty-three peats and swamp mucks I have examined. The ashes of the other half are largely mixed with sand and soil, but in most cases also contain considerable sulphate of lime, and often carbonates of lime and magnesia.

In one swamp-muck, from Milford, Conn., there was found but two _per cent._ of ash, at least one-half of which was sand, and the remainder sulphate of lime, (gypsum.) In other samples 20, 30, 50 and even 60 _per cent._ remained after burning off the organic matter. In these cases the ash is chiefly sand. The amount of ash found in those peats which were most free from sand, ranges from five to nine _per cent._ Probably the average proportion of true ash, viz.: that derived from the organic matters themselves, not including sand and accidental ingredients, is not far from five _per cent._

In twenty-two specimens of European peat, examined by Websky, Jaeckel, Walz, Wiegmann, Einhof and Berthier, eleven contained from 0.6 to 3.5 _per cent._ of ash. The other eleven yielded from 5.3 to 22 _per cent._ The average of the former was 2.4, that of the latter 12.7 _per cent._ Most of these contained a considerable proportion of sand or soil.

Variation in the composition as well as in the quantity of ash is very great.

Three analyses of peat-ashes have been executed at the author's instance with the subjoined results:

ANALYSES OF PEAT-ASHES. ---------------------------+-----------+-----------+---------- | A. | B. | C. Potash. | 0.69 | 0.80 | 3.46 Soda. | 0.58 | | trace. Lime. | 40.52 | 35.59 | 6.60 Magnesia. | 6.06 | 4.92 | 1.05 Oxide of iron and alumina. | 5.17 | 9.08 | 15.59 Phosphoric acid. | 0.50 | 0.77 | 1.55 Sulphuric acid. | 5.52 | 10.41 | 4.04 Chlorine. | 0.15 | 0.43 | 0.70 Soluble silica. | 8.23 | 1.40 } | Carbonic acid. | 19.60 | 22.28 } | 67.01 Sand. | 12.11 | 15.04 } | +-----------+-----------+---------- | 99.13 | 100.74 | 100.00 ---------------------------+-----------+-----------+----------

A was furnished by Mr. Daniel Buck, Jr., of Poquonock, Conn., and comes from a peat which he uses as fuel.

B was sent by Mr. J. H. Stanwood, of Colebrook, Conn.

C was sent from Guilford, Conn., by Mr. Andrew Foote.[5]

A and B, after excluding sand, are seen to consist chiefly of carbonates and sulphates of lime and magnesia. III. contains a very large proportion of sand and soluble silica, much iron and alumina, less lime and sulphuric acid. Potash and phosphoric acid are three times more abundant in C than in the others.

Instead of citing in full the results of Websky, Jaeckel and others, it will serve our object better to present the maximum, minimum and average proportions of the important ingredients in twenty-six recent analyses, (including these three,) that have come under the author's notice.

VARIATIONS AND AVERAGES IN COMPOSITION OF PEAT-ASHES.

_Minimum._ _Maximum._ _Average._ Potash 0.05 to 3.64 0.89 per cent. Soda none " 5.73 0.83 " Lime 4.72 " 58.38 24.00 " Magnesia none " 24.39 3.20 " Alumina 0.90 " 20.50 5.78 " Oxide of iron none " 73.33 18.70 " Sulphuric acid none " 37.40 7.50 " Chlorine " " 6.50 0.60 " Phosphoric acid " " 6.29 2.56 " Sand 0.99 " 56.97 25.50 "

It is seen from the above figures that the ash of peat varies in composition to an indefinite degree. Lime is the only ingredient that is never quite wanting, and with the exception of sand, it is on the average the largest. Of the other agriculturally valuable components, sulphuric acid has the highest average; then follows magnesia; then phosphoric acid, and lastly, potash and soda: all of these, however, may be nearly or quite lacking.

Websky, who has recently made a study of the composition of a number of German peats, believes himself warranted to conclude that peat is so modified in appearance by its mineral matters, that the quantity or character of the latter may be judged of in many cases by the eye. He remarks, (_Journal fuer Praktische Chemie, Bd. 92, S. 87_,) "that while for example the peats containing much sand and clay have a red-brown powdery appearance, and never assume a lustrous surface by pressure; those which are very rich in lime, are black, sticky when moist, hard and of a waxy luster on a pressed surface, when dry: a property which they share indeed with very dense peats that contain little ash. Peats impregnated with iron are easily recognized. Their peculiar odor, and their changed appearance distinguish them from all others."

From my own investigations on thirty specimens of Connecticut peats, I am forced to disagree with Websky entirely, and to assert that except as regards sand, which may often be detected by the eye, there is no connection whatever between the quantity or character of the ash and the color, consistency, density or any other external quality of the peat.

The causes of this variation in the ash-content of peat, deserve a moment's notice. The plants that produce peat contain considerable proportions of lime, magnesia, alkalies, sulphuric acid, chlorine and phosphoric acid, as seen from the following analysis by Websky.

COMPOSITION OF THE ASH OF SPHAGNUM.

Potash. 17.2 Soda. 8.3 Lime. 11.8 Magnesia. 6.7 Sulphuric acid. 6.5 Chlorine. 6.2 Phosphoric acid. 6.7 _Per cent._ of ash, 2.5.

The mineral matters of the sphagnum do not all become ingredients of the peat; but, as rapidly as the moss decays below, its soluble matters are to a great degree absorbed by the vegetation, which is still living and growing above. Again, when a stream flows through a peat-bed, soluble matters are carried away by the water, which is often dark-brown from the substances dissolved in it. Finally the soil of the adjacent land is washed or blown upon the swamp, in greater or less quantities.

III.--_The decomposition of peat in the soil offers some peculiarities_ that are worthy of notice in this place. Peat is more gradual and regular in decay than the vegetable matters of stable dung, or than that furnished by turning under sod or green crops. It is thus a more steady and lasting benefit, especially in light soils, out of which ordinary vegetable manures disappear too rapidly. The decay of peat appears to proceed through a regular series of steps. In the soil, especially in contact with soluble alkaline bodies, as ammonia and lime, there is a progressive conversion of the _insoluble_ or _less soluble_ into _soluble_ compounds. Thus the inert matters that resist the immediate solvent power of alkalies, absorb oxygen from the air, and form the humic or ulmic acids soluble in alkalies; the humic acids undergo conversion into crenic acid, and this body, by oxidation, passes into apocrenic acid. The two latter are soluble in water, and, in the porous soil, they are rapidly brought to the end-results of decay, viz.: water, carbonic acid, ammonia and free nitrogen.

Great differences must be observed, however, in the rapidity with which these changes take place. Doubtless they go on most slowly in case of the fibrous compact peats, and perhaps some of the lighter and more porous samples of swamp muck, would decay nearly as fast as rotted stable dung.

It might appear from the above statement, that the effect of exposing peat to the air, as is done when it is incorporated with the soil, would be to increase relatively the amount of soluble organic matters; but the truth is, that they are often actually diminished. In fact, the oxidation and consequent removal of these soluble matters (crenic and apocrenic acids,) is likely to proceed more rapidly than they can be produced from the less soluble humic acid of the peat.

IV.--_Comparison of Peat with Stable Manure._

The fertilizing value of peat is best understood by comparing it with some standard manure. Stable manure is obviously that fertilizer whose effects are most universally observed and appreciated, and by setting analyses of the two side by side, we may see at a glance, what are the excellencies and what the deficiencies of peat. In order rightly to estimate the worth of those ingredients which occur in but small proportion in peat, we must remember that it, like stable manure, may be, and usually should be, applied in large doses, so that in fact the smallest ingredients come upon an acre in considerable quantity. In making our comparison, we will take the analysis of Peat from the farm of Mr. Daniel Buck, Jr., of Poquonock, Conn., and the average of several analyses of rotted stable dung of _good quality_.

No. _I_, is the analysis of Peat; No. _II_, that of well rotted stable manure:--

_I._ _II._ Water expelled at 212 degrees. 79.000 79.00 {Soluble in dilute solution } Org. { of carbonate of soda. 7.312 } Matter. {Insoluble in solution } 14.16 { of carbonate of soda. 12.210 } Potash. 0.010 0.65 Soda. 0.009 Lime. 0.608 0.57 Magnesia. 0.091 0.19 Phosphoric acid. 0.008 0.23 Sulphuric acid. 0.082 0.27 Nitrogen. 0.600 0.55 Matters, soluble in water. 0.450 4.42

To make the comparison as just as possible, the peat is calculated with the same content of water, that stable dung usually has.

We observe then, that the peat contains in a given quantity, _about one-third more organic matter, an equal amount of lime and nitrogen_; but is _deficient in potash, magnesia, phosphoric and sulphuric acids_.

The deficiencies of this peat in the matter of composition may be corrected, as regards potash, by adding to 100 lbs. of it 1 lb. of potash of commerce, or 5 lbs. of unleached wood-ashes; as regards phosphoric and sulphuric acids, by adding 1 lb. of good superphosphate, or 1 lb. each of bone dust and plaster of Paris.

In fact, the additions just named, will convert _any fresh peat_, containing not more than 80 _per cent._ of water and not less than 20 _per cent._ of organic matter, into a mixture having as much fertilizing matters as stable dung, with the possible exception of nitrogen.

It is a fact, however, that two manures may reveal to the chemist the same composition, and yet be very unlike in their fertilizing effects, because their conditions are unlike, because they differ in their degrees of solubility or availability.

As before insisted upon, it is true in general, that peat is more slow of decomposition than yard-manure, and this fact, which is an advantage in an amendment, is a disadvantage in a fertilizer. Though there may be some peats, or rather swamp mucks, which are energetic and rapid in their action, it seems that they need to be applied in larger quantities than stable manure in order to produce corresponding fertilizing effects. In many cases peat requires some preparation by weathering, or by chemical action--"fermentation"--induced by decomposing animal matters or by alkalies. This topic will shortly be discussed.

We adopt, as a general fact, the conclusion that peat is inferior in fertilizing power to stable manure.

Experience asserts, however, with regard to some individual kinds, that they are equal to common yard manure without any preparation whatever.

Mr. Daniel Buck, of Poquonock, Conn., says, of the 'muck,' over-lying the peat, whose composition has just been compared with stable manure, that it "has been applied fresh to meadow with good results; the grass is not as tall but thicker and finer, and of a darker green in the spring, than when barn-yard manure is spread on."

A swamp muck, from Mr. A. M. Haling, Rockville, Conn., "has been used as a top-dressing, on grass, with excellent results. It is a good substitute for barn-yard manure."

A peat, from Mr. Russell U. Peck, of Berlin, Conn., "has been used fresh, on corn and meadow, with good effect."

Of the peat, from the 'Beaver Pond,' near New Haven, Mr. Chauncey Goodyear, says, "it has been largely used in a fresh state, and in this condition is as good as cow dung."

Mr. Henry Keeler, remarks, concerning a swamp muck occurring at South Salem, N. Y., that "it has been used in the fresh state, applied to corn and potatoes, and appears to be equal to good barn manure:" further:--"it has rarely been weathered more than two months, and then applied side by side with the best yard manure has given equally good results."

A few words as to the apparent contradiction between Chemistry, which says that peat is not equal to stable dung as a fertilizer, and Practice, which in these cases affirms that it is equal to our standard manure.

In the first place, the chemical conclusion is a general one, and does not apply to individual peats, which, in a few instances, may be superior to yard manure. The practical judgment also is, that, in general, yard manure is the best.

To go to the individual cases; second: A peat in which nitrogen exists in as large a proportion as is found in stable or yard manure, being used in larger quantity, or being more durable in its action, may for a few seasons produce better results than the latter, merely on account of the presence of this one ingredient, it may in fact, for the soil and crop to which it is applied, be a better fertilizer than yard manure, because nitrogen is most needed in that soil, and yet for the generality of soils, or in the long run, it may prove to be an inferior fertilizer.

Again; third--the melioration of the physical qualities of a soil, the amendment of its dryness and excessive porosity, by means of peat, may be more effective for agricultural purposes, than the application of tenfold as much fertilizing, _i. e._ plant-feeding materials; in the same way that the mere draining of an over-moist soil often makes it more productive than the heaviest manuring.

2.--_On the characters of Peat that are detrimental, or that may sometimes need correction before it is agriculturally useful._

I.--_Bad effects on wet heavy soils._

We have laid much stress on the amending qualities of peat, when applied to dry and leachy soils, which by its use are rendered more retentive of moisture and manure. These properties, which it would seem, are just adapted to renovate very light land, under certain circumstances, may become disadvantageous on heavier soils. On clays no application is needed to retain moisture. They are already too wet as a general thing.

Peat, when put into the soil, lasts much longer than stubble, or green crops plowed in, or than long manure. If buried too deeply, or put into a heavy soil, especially if in large quantity, it does not decay, but remains wet, and tends to make a bog of the field itself.

For soils that are rather heavy, it is therefore best to compost the peat with some rapidly fermenting manure. We thus get a compound which is quicker than muck, and slower than stable manure, etc., and is therefore better adapted to the wants of the soil than either of these would be alone.

Here it will be seen that much depends on the character of the peat itself. If light and spongy, and easily dried, it may be used alone with advantage on loamy soils, whereas if dense, and coherent, it would most likely be a poor amendment on a soil which has much tendency to become compact, and therefore does not readily free itself from excess of water.

But even a clay soil, if _thorough-drained and deeply plowed_, may be wonderfully improved by even a heavy dressing of muck, as then, the water being let off, the muck can exert no detrimental action; but operates as effectually to loosen a too heavy soil, as in case of sand, it makes an over-porous soil compact or retentive. A clay may be made friable, if well drained, by incorporating with it any substance as lime, sand, long manure or muck, which interposing between the clayey particles, prevents their adhering together.

II.--_Noxious ingredients._

a. _Vitriol peat._ Occasionally a peat is met with which is injurious if applied in the fresh state to crops, from its containing some substance which exerts a poisonous action on vegetation. The principal detrimental ingredients that occur in peat, appear to be sulphate of protoxide of iron,--the same body that is popularly known under the names copperas and green-vitriol,--and sulphate of alumina, the astringent component of alum.

I have found these substances ready formed in large quantity in but one of the peats that I have examined, viz.: that sent me by Mr. Perrin Scarborough; of Brooklyn, Conn. This peat dissolved in water to the extent of 15 _per cent._, and the soluble portion, although containing some organic matter and sulphate of lime, consisted in great part of green-vitriol.

Portions of this muck, when thrown up to the air, become covered with "a white crust, having the taste of alum or saltpeter."

The bed containing this peat, though drained, yields but a little poor bog hay, and the peat itself, even after weathering for a year, when applied, mixed with one-fifth of stable manure to corn in the hill, gave no encouraging results, though a fair crop was obtained. It is probable that the sample analyzed was much richer in salts of iron and alumina, than the average of the muck.

Green-vitriol in minute doses is not hurtful, but rather beneficial to vegetation; but in larger quantity it is fatally destructive.

In a salt-marsh mud sent me by the Rev. Wm. Clift, of Stonington, Conn., there was found sulphate of iron in considerable quantity.

This noxious substance likewise occurred in small amount in swamp muck from E. Hoyt, Esq., New Canaan, Conn., and in hardly appreciable quantity in several others that I have examined. Besides green-vitriol, it is possible that certain organic salts of iron, may be deleterious.

The poisonous properties of vitriol-peats may be effectually corrected by composting with lime, or wood-ashes. By the action of these substances, sulphate of lime, (plaster of Paris) is formed, while the iron separates as peroxide, which, being insoluble, is without deleterious effect on vegetation. Where only soluble organic salts of iron (crenate of iron) are present, simple exposure to the air suffices to render them innocuous.

b. _The acidity of Peats._--Many writers have asserted that peat and muck possess a hurtful "acidity" which must be corrected before they can be usefully employed. It is indeed a fact, that peat consists largely of acids, but, except perhaps in the vitriol-peats, (those containing copperas,) they are so insoluble, or if soluble, are so quickly modified by the absorption of oxygen, that they do not exhibit any "acidity" that can be deleterious to vegetation. It is advised to neutralize this supposed acidity by lime or an alkali before using peat as a fertilizer or amendment, and there is great use in such mixtures of peat with alkaline matters, as we shall presently notice under the head of composts.

By the word acidity is conveyed the idea of something hurtful to plants. This something is, doubtless, in many cases, the salts of iron we have just noticed. In others, it is simply the inertness, "coldness" of the peat, which is not positively injurious, but is, for a time at least, of no benefit to the soil.

c. _Resinous matters_ are mentioned by various writers as injurious ingredients of peat, but I find no evidence that this notion is well-founded. The peat or muck formed from the decay of resinous wood and leaves does not appear to be injurious, and the amount of resin in peat is exceedingly small.

3.--_The Preparation of Peat for Agricultural use._