My sole apology for troubling your Excellency with any communication foreign to the immediate duties of your high & important station is its estimated consequence to the prosperity of the country over which you preside. The doctrin I purpose to maintain in this Letter, if true, is of more importance than perhaps any modern discovery whatever; and if it is of such consequence, your Excellency is the most proper person in America to give it a due consideration in the country at large.

The world, Sir, is favored with many valuable tracts upon agriculture, & many experiments have been made to ascertain the best kinds of manure, as well as the best modes of applying them, for the purpose of enriching exhausted fields. But as most kinds of manure are scarce, and too expensive for universal use among all descriptions of farmers, it would be an acquisition of infinite magnitude to an agricultural people, to find a mode of restoring or preserving the fertility of lands, which should be simple, cheap & efficacious.

While therefore I allow, in its full extent, the value of stable manure, marl, plaster of Paris, lime, ashes, sea-weed, sea-shells, & salt, in enriching land, I believe none of them are absolutely necessary, but that nature has provided an inexhaustible store of manure, which is equally accessible to the rich & the poor, & which may be collected & applied to land with very little labor and expense. This store is the atmosphere, & the process by which the fertilizing substance may be obtained is vegetation.

The principle on which this opinion is founded, is one that is well known & admitted in the philosophic world, viz., that all plants imbibe a part of their nourishment from the air or common atmosphere. It is hardly necessary to mention the multitude of facts which demonstrate this principle, since it is universally admitted by the observers of nature’s works. But I am inclined to think that more nourishment is received in this manner, than even Philosophers are willing to allow, and for this opinion, my reasons ought to be assigned.

I. It is found by observation that six tenths of the whole surface of plants is above ground; that the surface of the body & limbs exceeds that of the roots by one tenth.1 More than half the inhaling pores therefore must be above ground; even when the tree or plant is without leaves. But add to this the whole surface of the leaves, when full grown, all of which are porous & designed by nature for the very purpose of feeding the plant, and your Excellency will readily concieve that nine tenths, perhaps a much larger proportion of the absorbing vessels are above ground. By the structure of plants then I judge a large proportion of their nutriment to be derived from the atmosphere.

II. Branches of trees which are over topped by other branches always perish, & few or no plants will flourish well under other plants. This is not merely because such plants or branches are shaded & deprived of the necessary phlogiston; the principal reason is that the under branches of trees are deprived of the dews, by the higher branches. But if the most of their nourishment were derived from the root, the lower branches would be the best fed & the upper branches would decay. This is capable of demonstration. It is indeed a wise provision of nature’s author, that no two branches should shoot from the same side of a tree; or at least that if one branch shoots out in a line directly over another branch, it is always at a great distance. This arrangement is evidently intended to give the different branches an opportunity of spreading their leaves over the whole circumference of space about the tree that is within their reach, as well as to embrace the vessels from the roots on all sides without interfering with each other. By the whole arrangement, it evidently appears that nature designed the branches to feed upon the atmosphere, and where they are deprived of this sustenance, they must perish. This is most obvious in large forests, where the ground is covered with dry leaves; for here the dews are very inconsiderable; whereas when a tree stands alone in a field, the dews there being copious, they rise among the under branches & supply them with nourishment. Hence a single tree spreds & all its branches liv & flourish; while the trees of a thicker forest grow tall, the upper branches only finding sufficient nourishment.2

These facts, which must have fallen under your Excellency’s notice, render it probable, not that a part merely, but a large part of the nutritious matter of vegetables is derived from the atmosphere. Hundreds of other facts may be mentioned, but it is needless.

From this theory I draw the most important consequences for agriculture: for if true, land may be made as rich as we please, without any of the common manuring substances. It is not clearly decided what are the simple component parts of vegetables; but modern chymists allow that all plants contain oil, salt, water & earth. Some at least of these substances, which constitute the very essence of manure, exist in common air, particularly the nitrous acid. I know little or nothing of chymistry, & shall therefore confine my remarks to facts within vulgar observation or principles universally admitted.

It is well known that dung of cattle is some of the best manure in the world. Is this any thing more than vegetables decompounded by putrefaction & the fat, oleaginous, nitrous and earthy particles separated from the water & phlogiston? Is the body of an animal composed of substances which are not common to plants? Most clearly not. The principal ingredients in animal bodies, in vegetables & in the manure we carry upon our fields are the same under different forms and in different proportions.

Vegetables then contain the substances which constitute manure, & the process from a plant to manure, & from manure to a plant is the process of nature, & consists in vegetation & putrefaction. Let me then ask your Excellency, will not land contract fertility by a spontaneous growth of vegetables, provided they are suffered to putrify upon its surface? You will doubtless answer in the affirmativ, for what is the black mould in valleys, in forests & on the banks of rivers, but mere putrified vegetables, or a mixture of these with natural earth?

If then a spontaneous growth of trees or plants will enrich land, by what means do they add to the fertilizing substances already in the soil? If they derive their nourishment from the earth solely, when they perish they would leave upon the earth no more than they took from it, & consequently the land would be no better; whereas every man sees they enrich land. There is no way to account for the effect, but by supposing the plants to derive a considerable part of their nutrition from the air.

It is a common remark of the farmers in New England, that rye does not exhaust land, but if the stubble is turned in as soon as a crop is taken off, the land will rather grow richer under continued crops of this article. Whatever fanciful reasons may have been assigned for this effect, the real truth is, the stubble contains more of the manuring substances than the whole crop takes from the earth. This is but one of numberless common facts, which might be mentioned to prove my theory. Again, a certain farmer in this naborhood sometimes made it a practice, after mowing his fields twice, to let the third crop rot upon the land, and this small growth, which is generally fed by cattle in October & November, was amply sufficient to manure the land for the next season. In this case, a fifth or a seventh of the annual growth kept the land always rich.

No. 23

The use of clover in enriching exhausted fields is derived from the same principle. Farmers tell us that clover benefits land by its roots which warm & loosen the earth; but the fact is, clover imbibes a great part of its nourishment from the air, & even when mowed or fed, there is still a considerable quantity of the stalks left on the earth, which, when turned in, serve to enrich it. Clover indeed, when the crop is taken off, has but little effect as manure, but when the full growth is plowed in, it is equal to a heavy covering of manure. But any vegetable will have the same effect, tho perhaps in a different degree; for every plant imbibes the nutritious substances from the air.

The conclusion to be drawn from these principles & facts is; that lands should never be without some vegetable growing upon them, the vessels of which are the conduit pipes to convey nourishment from the air to the earth, or rather are nature’s chymical instruments to decompound the atmosphere, & collect the nutritious oil & salts. Old fields which are exhausted by long cultivation are enriched in two ways only; one is by a coat of manure of some kind; the other is by a spontaneous growth of weeds & grass, which, after some years, will restore fertility. But why should these old fields be neglected? The roots of vegetables have been destroyed by previous cultivation; no seed is put upon the land; the earth is left naked; there is nothing upon it to attract the nitrous particles of the air, until a spontaneous growth of weeds arises & answers this purpose, & then requires two or three years or more. Why all this waste of time? Is it not throwing away the profits of a farm?

I believe Sir, fertility may be restored to exhausted fields in a much more expeditious way, by seeding them with some succulent vegetables, as oats, peas, beans, buckwheat, & turning in the full growth or suffering the whole to rot upon the land. An exhausted field will indeed produce but a small crop; but a small growth turned in with a plow, will be sufficient to enrich the land in a considerable degree, & prepare it for a large crop. I concieve it best to plow in the vegetable just as it arrives to full growth; for the whole substance is then preserved in the land, & being covered, it ferments & loosens the earth; whereas if the vegetable is suffered to fall upon the surface, a part of the manuring substances may be evaporated or washed off by rains.

If land is become very poor & the owner wishes to enrich it as much as possible in one season, it may be sowed with oats early in the spring & the oats at full growth may be turned in, in good time to sow the land with buck-wheat, which may likewise be turned in before it seeds. Thus two crops of succulent vegetables may be obtained in one summer, & these would probably be equal to many tons of Stable manure upon an acre. Peas are perhaps the best vegetable for manuring land, but the seed is more expensive than oats. Cheapness is an essential article in any general plan of manuring impoverished fields, and I know of none so cheap as this. Two bushels of oats and one day’s labor for a man & one pair of oxen will answer for seeding an acre of land; and another day’s labor will be sufficient to turn in the crop. At any rate, this means of fertilizing land is within the power of every cottager in any part of the country; a circumstance that gives it a preference to every other method.

It is a common complaint in Virginia that the best tobacco lands are impoverished, & the culture of that article is said to be on the decline. An eminent writer of that State4 predicts that the culture of tobacco must still decline, because the price of the article abroad will not defray the expense of manure. This is doubtless true of the common manure, but whence, let me ask, did the lands in Virginia derive their original fertility? Was it not from the putrefaction of vegetables? Is any thing necessary to restore the fertility except the same process? And will not a little human assistance expedite the process of nature? Is it necessary to wait an age or two for the lands to be covered with forests in order to secure a mass of putrid vegetables? Will not any succulent plant, the growth of a summer, supply the same matter, which is derived from the leaves of large trees? Where then is the difficulty or expense of recruiting the barren fields?

I have no doubt that tobacco itself is the best of manure. It is not a staple in the New England States; but some towns on Connecticut River raise considerable quantities & the plant grows to a larger size than in Virginia. After the plant is cured & the leaves stripped from the stalks the farmers throw the stalks upon their fields; & consider them as rich manure. Now tobacco, like hemp & flax, is a plant which impoverishes land, much sooner than most vegetable productions. It undoubtedly imbibes a much larger proportion of oil & salts from the earth than most plants; or if not, it imbibes more of these substances from the air than other plants, in proportion to its size. It is not material which hypothesis we embrace, so long as it is well known that the plant has an uncommon share of these substances in its composition, and it is well known that all plants imbibe a part of their substance from the atmosphere. In either case, tobacco is a rich manure, the seed costs very little, and any exhausted field will produce small plants. Suppose then the seed should be sprinkled over one of these worn out tobacco fields just after a rain, a drag or harrow drawn over the land to cover the seed, and the plants suffered to grow without culture. The plants would be small, but every where covering the field, they would inhale a large share of the manuring particles of the air, which, by the dissolution of the plant, would mingle with the earth. I have never seen or heard of this experiment; but it is so agreeable to facts within my observation & so analagous to the process of nature, in uncultivated wild lands, that I have no doubt in my own mind, one light growth of plants, either plowed in or putrifying upon the surface, would produce two or three valuable crops; and that a repetition of this process for two or three seasons would restore to the soil its primitiv fertility. I here suppose the tobacco seed to be merely scattered on the land & followed with a drag, harrow or branch of a tree, which would be very little trouble; for it might be a needless expense to grub up the land with hoes, & plows are little used on the tobacco plantations.

I recollect when I was in Virginia in 1785,5 your Excellency was carrying upon your fields mud from the creeks of the Potomak. “Success to the mud,” was a toast at dinner, and I have no doubt it had a good effect as manure. But, Sir, why is mud from the bottoms of rivers manure? It may, in the Potomak, contain a mixture of marine salt; but the muddy bottoms of all fresh rivers & marshy grounds are a rich manure. This is a well known fact; and can the manuring qualities of this earth be derived from any source, but from vegetable putrefaction, the mass of which has been washed down from the naboring declivities? In short, Sir, I cannot but think that, by, a proper attention to the operations of nature, we might be enabled to manure our lands, without digging for marl or importing plaster of Paris. This at least might be the case while we have more land than we can cultivate every year; for if the country should ever become so populous as to require crops to be taken from land every year, the inhabitants will find it necessary to have recourse to artificial methods of enriching their lands.

For fear of intruding too much on your Excellency’s time & goodness, I shall close this letter, with just remarking that I claim no merit for discovering any new principles on this subject. Philosophers will know that plants absorb nutriment from the air, and farmers will know that when grass, leaves and other vegetables rot upon land, they enrich it. And the reason why this most simple obvious way of fertilizing land, by seeding it for the express purpose, should not have become a more general practice, is to me a mystery. Indeed the obviousness of the thing almost persuades me that my ideas on the subject are wrong, & that I place more dependence on this process for enriching the earth, than experience itself will warrent. Yet when I converse with people, & find scarcely a man that knows or will believe that vegetables grow by absorbing from the air as well as from the earth; & when, from several years enquiry, I can find scarcely a farmer who knows the true reason why vegetable productions, putrifying on land, serve to enrich it; I cannot but think that an attempt to unfold the reason, & introduce a method of repairing exhausted fields very simple, cheap & accessible to every poor man, will be benificial to the agricultural interests of my Country. I consider myself as writing to the most judicious & experienced Planter in America; Should your Excellency be of opinion that this letter contains any thing new or useful, please to communicate the sentiments & facts, but wholly suppress my name. Otherwise please to suppress both my name & the letter.

No. 3

Please Sir, to accept the volumes6 accompanying this, as a pledge of my inviolable attachment to your person & government. I have written much in the cause of my country, & God knows I am actuated by the best of motivs, however I may have been abused & misrepresented by a censorious world. Please to accept my most cordial wishes for the success of your administration & the happiness of yourself & family.7 I have the honor to be your Excellency’s most obedient most humble Servt