Agriculture in some of its relations with chemistry;

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Chapter I. Composts

In diflcussing methods of preserving fannyaid manure, as in the last chapter of the first volume, the question of compost-making naturally presents itself, and attention is called forcihly to the consideration of several well-known fieusts which hear upon this suhject

It is a matter of old ohservation, that, if some kinds of peat he mixed with fresh stahle manure in the proportion of two or three loads of the peat to one load ot»the dung, and the mixture he then allowed to ferment, there will he ohtained a compound as efficient, load for load, for many fertilizing purposes, as pure stahle manure. The ohservation has often heen verified in this country, as well as in Europe, and cannot he gainsaid. Douhtless several causes conspire to produce this result. The fertilizing qualities proper to the peat are utilized, and the fermentation which it undergoes conduces to this end. The power of the peat to ahsorh and hold water comes into play also. But there is still ample room left for the argument that, owing to the presence of the peat in the mixture, the stahle manure has fermented to hotter advantage than it would have done hy itself. This thought not only hears directly upon the question of preparing composts with dung, hut, as has already heen suggested, it is most intimately connected with the prohlem how hest to preserve manures.

Composing mves Manure.

As matters actually stand, there appears to he little douht that the results of practical experience teach that, in many situations, a larger proportion of the useful ingredients of dung and urine can he saved by mixing these substances with comparatively large quantities of peat, or loam, or clay, or straw, before fermentation has set in, than by suffering the manure to ferment in the barnyard by itself. But in such admixture may be seen the beginnings of the so-called process of composting, and it may be said, truly enough, that composting is practised in some sort wherever loam and peat, or even straw, are used for bedding animals.

It may be well at this point to recur to the practical experience of farmers, and to cite some new examples from it, though it needs to be said, at the jstart, that many farmers have strongly objected to the use of loai]Q bedding in cow stables. Their objections are based, however, mainly upon the dirtiness of the earth and the labor of handling it ; they do not depend upon chemical considerations, and most farmers seem to agree that cow manure may be very well preserved by the earth. Some farmers have claimed, indeed, that cows can be kept clean enough for all practical purposes by using straw for bedding them, in conjunction with the loam ; and they hold that the trouble thus taken is more than paid for by the comfort of the animals and the increase of manure. Probably peat or loam covered with sawdust would serve a good purpose.

Loam for bedding Animals,

Rotenhan, in Germany, describes as follows his method of bedding 100 head of neat cattle during the winter months on nothing but loam. A line of heavy joists is laid down and firmly fastened to the floor behind the animals, i. e. between them and the gangway, in order to hold the loam in place. The whole of the standing-room between these joists and the cribs is filled with a layer of dry loam, the depth of which is as much as 8 or 10 inches at the rear, i. e. next the joist. In this way a horizontal layer of earth is provided for the animals to stand upon.

Three or four times a day the dung, with whatever loam has become moistened with urine, is scraped out and left in little heaps behind the animals, while the holes and irregularities of surface that have been made by removing the loam are filled up or smoothed off by scraping into them earth from other parts of the bed. Once a day the heaps of dung and loam are thrown out into the yard. At the end of every fortnight or three weeks, the standing-room is cleaned out and a new layer of loam laid down in it, for the reason that the continual trampling of the cattle impacts the earth so firmly that it can no longer absorb urine as quickly as is desired.

coMPOsra 3

In Older tiksi the animals may be kept clean, dry, and healthy in this way, it is essential that the earth should be dry. Sandy loam does well, and so do loams rich in humus, but clays are bad. The more humus there is in the earth, so much the larger will its power of absorbing water be, and so much the smaller quantity of it will be required. The use of dry peat for this purpose is not uncommon. Rotenhan carted the loam in autumn and kept it under a roof. Each of his animals appears to have used as much as one or two two-horse loads of the loam every month. Heiden computes that, for 1000 lb. of live weight, cows will need some 180 lb. of loam (2^ cubic feet) per diem in order that they may stand tolerably dry.

Another way of applying the earth is cited by Professor Johnson in his essay on " Peat and its Uses.'* Mr. Holbrook of Brattleboro', Yt, every morning before cleaning the cow stable, throws a bushelbasketful of peat upon the dung behind each of the animals. The peat absorbs completely the urine and other moisture of the manure, which is held in a water-tight trench behind the animals, and the warm mixture soon enters into fermentation when thrown from the stable. Mr. Holbrook, looking at the matter as a making of manure from peat rather than as a saving of manure by peat, maintains that '' much more peat can be well prepared for use in the spring in this way, than by any of the ordinary methods of oompoating."

Compott Heaps,

Many farmers prefer to make their compost in heaps. A common plan is to lay down a bed of peat six or eight feet wide and a foot or so thick, to cover it with a layer of dung of somewhat less thickness, followed by another layer of peat, and so on, until the heap has become three or four feet high. Various proportions of peat are employed by different farmers in the preparation of these compost heaps. The ordinary range is from 1 to 5 loads of peat to 1 load of manure, according to the kind of peat and the quality of the dung. Rich dung from stall-fed horses or fatting cattle will bear more peat than that from animals less highly fed. If there be much stmw or other litter in the manure, less peat will be added to it than if the dung were clear. Besides, the farmer would naturally tend to use more or less peat in composting, according as his land is light and sandy and in need of humus, or already charged with that sabstanee.

The practical rule is, to use no more peat ''than can be thoroughly fermented by the manure/' though it may perhaps be fairly questioned whether this rule is well founded. Possibly a better rule would be, not to use enough peat or other admixture wholly to prevent the dung from fermenting.

In case the dung were free from long litter, it is possible, though not probable, that it might be still better to mix as much peat with the dung as will just prevent it from fermenting. But, in our ignorance of what the so-called process of fermentation is, it would be hard to determine which of the three rules is theoretically the best. If we could only be sure, when peat enough is used to prevent the dung from fermenting in the usual .way, that the heap would not proceed to ferment in some other unusual and hurtful way, and so destroy itself, the subject would be a good deal clearer than it is now. Probably there are many cases where it would be well to keep dung and urine in the barnyard fresh and raw, if that could be done without too much labor, even if the peat should remain unfermented. Whether this could ever be done without risk, and, if so, when and how, are point-s still to be studied. The probabilities are that it would not be very easy to do it unless the mixture were put in a silo. Hence the second rule suggested, not to use enough peat wholly to prevent the dung from fermenting, may possibly be the best of the three.

Practically, the amount of peat to be used must always be determined by considerations of economy relating to the particular &rm on which the compost is to be made. So long as peat can be hauled at small cost by men and teams belonging to the farm, at times when work is slack, and no more profitable way of expending the labor can be found, it will be well to haul it, provided that the cost of labor to be expended in preparing the compost and in distributing the bulky material in the fields is less than the cost of obtaining an equivalent quantity of commercial fertilizers would be.

Composts require much Labor.

As regards weight and the amount of water which it can hold in its pores, swamp muck difi^rs less from farmyard manure than might be supposed. As tested by Henry Stewart, a cubic foot of soft wet muck, such as could be cut like butter, although it was somewhat fibrous, weighed, as taken from the bog, 67 lb. When dried in warm air, it gave off 83% of water. At the same time, Stewart found that fresh horse manure, free from litter, when pressed

COMPOSTING. 5

tightly into a box with a rammer, weighed 64 lb. to the cubic foot ; and Uiat fresh cow manure, free from litter, and similarly packed, weighed 66^ lb. to the cubic foot Cow manure taken from the bottom of a heap, where it was saturated with urine and had be* come partly rotted, weighed 70^ lb. to the cubic foot.

On the other hand, it must always be remembered, that the commercial fertilizers are concentrated and compact^ and that the cost of distributing them is small. It is true, in &ct, that the widely extended use of these fertilizers in recent years, or rather the ability to procure them readily, has caused composts to fall into disrepute. Compost heaps are established much more rarely nowadays in New England than they were formerly ; though the remark, as quoted by Professor Johnson, that '* the composting of muck and peat with stable and barnyard manures is surely destined to become one of the most important items in farm management throughout all the older States," is probably still true of a land of small proprietors, for whose labor there is at times no profitable outgo. It can hardly be accepted, however, as it stands, with regard to farms worked by hired labor for the sake of money profit only. In the immediate Ticinity of a city, moreover, it would usually be more profitable to expend labor in hauling out horse dung or night-soil than in building compost heaps.

Compotting saves IfUrogen.

As has been said already, hardly anything is known as to the chemical changes which occur when manures or composts ferment. It is to be presumed, that, economically speaking, no process of fermentation can do much more than change the things which are originally present in the dung or in the peat into new forms. It is hardly to be supposed that enough nitrogen can be absorbed from the air and fixed in a single compost heap to be of much practical significance. And yet there are many peats, which lon^ experience has shown to be excellent for making composts, that appear to contain only a very small amount of matters useful for vegetation. A peat of excellent reputation, analyzed by Professor Johnson, was found to contain, when in the air-dried state, three per cent of ashes, more than half of which was mere sand, and one and a half per cent of nitrogen, upon which, of course, the chief value of the material must depend. This peat was composed almost entirely of carbon, hydrogen, and oxygen, neither of which elements can be classed among fertilizing substances ; whence it is plain that, excepting as g AGRICULTURE.

regards its nitrogen, no very large amount of plant food can be got directly from a peat even so good as this one.

But there are several ways of accounting for the utility of peats that are poor in nitrogen. First of all, it is to be noticed that peat, at least when in its crude state, is an antiseptic or germicide agent of considerable power. Sour peat will kill the microdemes that cause fermentation, or prevent them from thriving, so that fermentation could hardly occur in presence of any considerable quantity of it. This fact goes far to explain how it is that peat, when used for bedding animals or for absorbing their liquid dejections, serves so well to preserve the manure, i. e. by delaying fermentation.

Moreover the humic acids in peat, even that which has been thoroughly weathered, are highly effective agents for absorbing am* monia. In this respect, Professor Johnson found that a swamp muck from the neighborhood of New Haven was capable of absorbing 1.3% of ammonia, while ordinary soil absorbed only from 0.1 to 0.5%. Heiden also noticed that a light fibrous crumbly peat used as litter in cow stables, which contained when air-dried 0.37% of ash ingredients and 93% of organic matter, of which 11% was humic acid and 0.64% was nitrogen, was capable of binding 1.6% of ammonia. He urges that such peat would be excellent for composting with night-soil, and that the product would be a good manure for light lands.

The results given in the table were obtained by D«tmer in experiments where ammonia gas was passed through tubes charged with mixtures of peat and sand.

The Miztura oontainod Per Cent Per Cent of Sand. of Peat.

There were al»-

Borbed Grams

of Ammonia.

SacblOOOcaBtortliii

Peat absorbed Qramt

of Ammonia.

• •

0.093

...

0.187

2.06

0.811

2.87

0.654

8.80

0.996

4-70

1.090

4.18

1.152

8.72

1.245

8.48

1.839

8.80

1.494

&80

ft •

1.712

8.42

In Germany crumbly peat has sometimes been used even for bedding horses, in such wise that a three or four inch layer of the peat is spread in the stalls and very thinly covered with straw. It is

COBIFOSTING. 7

mged, that haidly any odor of ammonia need be perceived in stables thus treated, and that it is easy enough to keep the hoises desn. Conyerseljy it is probable that one important step in the earing of peat in dung composts is the neutralizing of the sourness of the peat through the alkalinity of the ammonia, just as in com. posts made with lime or with potash the acidity of the peat is neutralized by these non-volatile alkalies.

Experiments made in England in 1856 have shown, not only tbat peat is really effective for holding ammonia, but that peat is decidedly better for this particular purpose than charcoal made from peat 500 grams, i. e. rather more than a pound, of peat and of peat-charcoaly respectively, were mixed with 355 grams of urine, and left to stand four days in the air together with a similar amount of mere urine. At the end of this time there was found in the plain urine as much nitrogen as would amount to 0.947 grm. of ammoma^ in that which had been mixed with the charcoal 0.233 grm., and in that admixed with the peat 1.105 grm., the excess of ammonia in the last-named case being credited to the nitrogen proper to the peat.

In another experiment, where 300 grams of the peat or the char^ ooal, each admixed with half an ounce of urine, were left five days over sulphuric acid under a bell glass, it was found that no ammonia had escaped from the peat, while the sulphuric acid under the charcoal bad absorbed 0.288 grm. of ammonia that had come to it, of conise in the form of gas.

Moreover, the carbonaceous matters in peat, even in those peats that are poor in nitrogen, probably serve a good purpose for feeding the nitric ferment whenever it appears upon the scene. It has been noticed, in £&ct, that the nitric ferment does not flourish excepting in presence of an abundant supply of carbonaceous food. Prom what has been said already under Farmyard Manure, it is plain that, in order tbat peat or other litter shall act to preserve manure, the mixture must be kept moist and firmly compacted. The risks which attend the free admission of air to such materials will be considered more fully hereafter.

It is known from analyses made by Professor Johnson, that peat can absorb and retain nitrogen from manures in some other form than that of ammonia. Thus, a peat, which in the crude air-dried state contained only as much nitrogen as would amount to 0.58% of ammonia, was found to contain nitrogen equivalent to 1.15% of ammonia after it had lain under the flooring of a horse stable for some time, where it had been partially saturated with urine. Some of the same kind of peat, after having been composted with fish, was found to contain nitrogen corresponding to nearly 1.31% of ammonia. It would appear in these cases, not only that some ammonia had been absorbed, but that either amids or other organic compounds of some kind had been formed by the decay of the nitrogenous constituents of the dung, the urine, or the fish. The amounts of nitrogen just mentioned seem large, in view of the fact that stable manure usually contains less than 1% of this element. And if it be true, as would seem clearly to be the case, that peat has the power to absorb and hold even as much as one half of 1% of its weight of nitrogen when composted with manure, the fact is one of great importance.

Perhaps the best way of illustrating the significance of the nitrogen in peat composts will be to recur yet again to the well-known practical fact, that the application of a very small quantity of active nitrogen is often sufficient to insure the growth of iarge cropia. A dressing of 250 to 400 lb. of Peruvian guano to the acre gives only from 50 to 70 lb. of ammonia, even if the guano be of excellent quality (15% N) ; and in order to obtain as much active nitrogen as this there would need to be applied to the land some 5,600 lb. of composted peat that contained 1.25% of ammonia. But in actual farm practice an ordinary rate of applying such compost is ten cords to the acre, and it is fair to suppose that each of these cords may weigh 4,000 lb. at the least

Curing of Peat.

Thus far the argument has been based almost wholly on the preservation of manure, and very little has been said of the improvement of peat, or of any other substance used for composts, at least not directly. But enough has been said indirectly to make it evident that much more remains to be urged on this side of the question. In fact, there cannot be any doubt that peat and loam, and leaves and straw, and many other organic matters which are comparatively inert in their natural or crude state, become more or less powerful manures after they have been fermented.

Mention has already been made of the fact, that a good part of the constituents of straw remain bound up, and unavailable as plant-food, until the organization of the straw is destroyed ; and the same remark will apply of course to all oiganized vegetable

COMPOSTING. 9

matters, such ajB leaves and stalks, and twigs or chips of wood. Bat by causing these inert matters to ferment, by mixing them with dung, or blood, or fish, or flesh, or any other putresoible or easily fermentable matter, their organization is quickly destroyed, and whatever of nutriment may he in them is made itn mediately available for crops. Thus in the fermentation uf bone-meal, while the conversion of the ossein is the chief det^ideratum, it may still fairly be inferred that the phosphate will be laid bare, and made more readily accessible to solvents and to the roots of plants than could have been the case if the particles of bone had not been decomposed and disintegrated.

Analogy, drawn from practical experience with fermented bone-meal and fish scrap, points to the conclusion that peat and straw, or other litter, may often be greatly improved when subjected to appropriate fermentation ; and Pagel has shown by methodical experiments that fermentation is really an efficient means for improving the inert nitrogen in many organic matters. He finds that much of the insoluble organic nitrogen is thus converted to soluble forms. But the fermentation must not be too violent, lest much of the nitrogen be wholly lost.

In these experiments, one set of boxes were charged with 100 lb. or more either of bone-meal or of fish guano that had been intimately mixed with some 35 or 40 quarts of either ox urine or dung Hquor, and the materials were then left to ferment ; while to another set of boxes, similarly charged, 10% of gypsum was added, and incorporated with the materials. The results of these trials are given in the table.

Per Cent of Per Cent of Materials QMKl originAl Nitro- original Nitro-

came Soluble. to Waste.

1. Rsh gnano, nrine, and gypsam (moist) . . 40.4 ...

2. Same as No. 1, without gypsam (very moist) . 48.8 ... 8. Bone-meal, dung liqnor, and gjrpsum, very

moist at first, afterwards dry 46.6 4.7

4. Bone-meal and arine (moderately moist) . . 80.0 89.3 6. Fiah gnano and small amoant of dung liquor,

incompletely moistened 42.5 4.8

From No. 3 it appears, as has often been shown by other experiments, that gypsum hinders the waste of nitrogen during fermentation. In No. 5 but little dung liquor was added in the beginning, in Older that the fermentation might be weak and slow. Pagel uigee that, in order that a fermentation may be regarded as proper, much heat must be developed by the materials. A thermometer thrust into the fermenting mixture should mark more than 100° F. The completion of the fermentation is indicated by the diminution of the high temperature. A considerable fall of temperature shows that action has ceased. But a new fermentation may be excited by forking over the heaps of materials, and moistening the dry places, best with dung liquor or urine. Too large a proportion of the urine, or other fermenting material, should not be used at^first, lest violent action should occur. For the particular case of bone-meal, 25 or 30 quarts of dung liquor to 110 lb. of the meal is considered to be a good proportion. *

More or less time is required for the completion of such fermentations, according as heat is developed slowly or speedily at first, and according as the heaps of material are large or small In general, 3 or 4 weeks will be sufficient for the completion of the process, when materials such as bone-meal or fish scrap are fermented.

Straw Comport.

On farms in Sweden belonging to the crown, where legal restrictions prevent the sale of straw, the excess of this material has sometimes been composted by drenching 6 or 8 feet high heaps of it with water, in which powdered rape cake has been soaked and stirred. The moist heap, loosely covered with earth 4 or 5 inches deep, is left to ferment for a month, and is then fwked over and again drenched with the rape-cake liquor. I'he heap is then left to itself until hauled out as manure. From 30 wagon loads of straw and 3 cwt. of rape cake, Bergstrand obtained nearly 30 wagon loads of '' manure " in the course of two mouths and a half. On comparing the product with stable manure by means of analysis, he obtained the following figures : —

Stnw Ordintiy

Compost. Fum Manure.

Oiganic matter 15.68 14.01

Phosphoric acid 0.10 0.20

Peat Compogts,

In the preparation of peat composts, dung and fish are the ferments

commonly used ; but urine, or guano, or the dung of fowls, would

PEAT COMPOSTS. 11

8erTe the purpoee excellently. Blood is objectionable^ because of the horribly offenaive odor which is exlialed by composts prepared with it. It might not be easy to say just what the substances are which smell so offensively, but there is every reason to believe that they have no agricultural significance. There is no greater fallacy than that which gauges the worth of a manure by the stench the manure emits.

By the process of fermenting, time is gained ; the organization of the vegetable matters is broken down in a few weeks or months in the compost heap, instead of resisting decay for a long time, as would be the case if the matters were left to themselves. This point might be illustrated by reference to an oak stump. Left to iteelf, the stump long resists decay, though the mould which finally reaolts from its decay is rich in plant-food. But the decay could soon be effected by reducing the fresh stump to the condition of saw-dust, and fermenting this saw-dust in any appropriate way. Another striking illustration was offered by the former use of woollen rags in French agriculture. These rags, as has been shown already, contained 12 to 14%, sometimes even 16 or 18%, of nitrogen^ but they decomposed so slowly in the soil that their action was felt on good moist land for 7 or 8 years, in case they were applied in the unfermented state. But when fermented by means of urine or guano-water, as was the French practice, they became a quick-acting and powerfid manure.

Peat abo, like the organized substances just mentioned, is often, not to say usually, very much improved by fermentation. As has been said, some kinds of peat serve very well as manure when applied to the soil directly, without weathering, fermentation, or preparation of any kind. Some sorts, moreover, ferment of themselves when thrown up into heaps, and exposed to warm, moist weather. But there are other kinds which are wellnigh useless as manures, unless they have either been rotted or fermented.

In view of these differences, it is not strange that some farmers should deem mere exposure of peat to the air to be a sufficient preparation of this material, for the practice may be judicious as regards some kinds of peat. It is often justified withal by considerations of labor and the cost of distribution. But the surest and safest way of obtaining good results with peat is to ferment it artificially in the compost heap. With peat, as with the vegetable matters, the usual fermenting agent is the dung of animals. Horse dung is esteemed to be the best kind, though urine would be better ; and fish has been used laigely for the purpose, especially on the southern coast of New £ngland. Guano has been used also as the ferment, in the proportion of one part of guano to 5 or 6 parts of peat. So also have blood and the ofial of slaughter^houscis, fish scrap, cotton-seed meal, soap-boiler's scraps, currier's scraps, nighV soil, and other easily decomposable animal or vegetable matters.

In case flesh is used, as when an animal has died from disease, it will be well to divide the flesh, and to distribute it in such manner that a tolerably equable mixture of it and the peat may be had. A small piece of flesh will ferment many times its own bulk of peat, provided it be brought into tolerably intimate contact vrith the peat. On account of the peculiarly offensive odor of such compost, it is best not to open the heaps except in winter weather. Such compost had better be hauled to the fields in cold weather, and ploughed under as soon as may be practicable in all cases. A similar remark will apply to composts made with night-soil. If care be taken to work upon such heaps in winter, the laborers will be less perturbed. There is one trouble with flesh-made composts, in that all the dogs in the countryside are apt to dig at the heaps.

In any event, care must be taken not to compost the flesh of animals which have died of infectious diseases. The researches of Pasteur have shown that the germs of the microscopic organism which causes splenic fever (malignant pustule), as well as various germs which produce putrefaction and septicaemia, are not destroyed in the compost heap, — not even when they are in actual contact with flesh in a state of putrefaction. Even when the diseased bodies of animals are buried in the ground at a depth of several feet, earthworms constantly bring up the malignant germs and deposit them, in their dung, at the surface of the soil. When these worm-casts are scattered as dust, or washed about by rains, portions of them cling to the grass or other herbage, and so infect the animals that feed upon it. Pasteur has urged that animals should never be buried in cultivated fields, mowing-fields, or pastures. Whenever possible, the bodies should be relegated to poor, dry, sandy, or chalky soils, not suited for the existence of earth-worms.