Part 8

My Microscope indeed is but a very ordinary one, and when I view with it the Liquor newly imbibed by a fibrous Root of a Mint, it seems more limpid than the clearest common Water, nothing at all appearing in it.

Either Roots must insume the Earth, that is their Pabulum, as they find it in whole Pieces, having intire Superficies of their own, or else such Particles as have not intire Superficies of their own, but want some Part of it, which adheres to, or is Part of the Superficies of larger Particles, before they are separated by Roots. The former they cannot insume (unless contained in Water); because they would fly away at the first Pores that were open: Ergo they must insume the latter.

A Plant cannot separate these Particles from the Parts to which they adhere, without the Assistance of Water, which helps to loosen them.

And ’tis also probable, that the Nitre of the Air may be necessary to relax this Superficies, to render the prolific Particles capable of being thence disjoin’d; and this Action of the Nitre seems to be what is call’d, Impregnating the Earth.

Since the grosser Vegetable Particles, when they have pass’d thro’ a Plant, together with their moist Vehicle, do fly up into the Air invisibly; ’tis not likely they should, in the Earth, fall off from the Superficies of the Pores, by their own Gravity: And if they did fall off, they might fly away as easily before they enter’d Plants, as they do after they have pass’d thro’ them; and then a Soil might become the poorer for all the Culture and Stirring we bestow upon it; tho’ no Plants were in it; contrary to Experience.

But we see it is always the richer by being frequently turned and exposed to the Atmosphere: Therefore Plants must take all their Pabulum from a Superficies of Parts of Earth; except what may perhaps be contained in Water fine enough to enter Roots intire with the Water.

It must be own’d, that Water does ever carry, in its Interstices, Particles of Earth fine enough to enter Roots; because I have seen, that a great Quantity of Earth (in my Experiments) will pass out of Roots set in Rain-water; and tis found that Water can never be, by any Art, wholly freed from its earthy Charge; therefore it must have carry’d in some Particles of Earth along with it: But yet I cannot hence conclude, that the Water did first take these fine Particles from the aforesaid Superficies: I rather think, that they are exhal’d, together with very small Pieces to which they adhere, and in the Vapour divided by the Aereal Nitre; and, when the Vapour is condens’d, they descend with it to replenish the Pasture of Plants; and that these do not enter intire into Roots, neither does any other of the earthy Charge that any Water contains; except such fine Particles which have already pass’d thro’ the Vegetable Vessels, and been thence exhal’d.

This Conjecture is the more probable, for that Rain-Water is as nourishing to Plants set therein as Spring-Water, tho’ the latter have more Earth in it; and tho’ Spring-water have some Particles in it that will enter intire into Roots, yet we must consider, that even that Water may have been many times exhal’d into the Air, and may have still retain’d a great Quantity of Vegetable Particles, which it received from Vegetable Exhalations in the Atmosphere; tho’ not so great a Quantity as Rain-water, that comes immediately thence.

These, I have to do with, are the Particles which Plants have from the Earth, or Soil; but they have also fine Particles of Earth from Water, which may impart some of its finest Charge to the Superficies of Roots, as well as to the Superficies of the Parts of the Earth which makes the Pasture of Plants.

If Water does separate, and take any of the mere Pabulum of Plants from the Soil, it gives much more to it.

Yet it seems, that much of the Earth, contain’d in the clearest Water, is there in too large Parts to enter a Root; since we see, that in a short time the Root’s Superficies will, in the purest Water, be cover’d with Earth, which is then form’d into a terrene Pasture, which may nourish Roots; but very few Plants will live long in so thin a Pasture, as any Water affords them. I cannot find one as yet that has liv’d a Year, without some Earth have been added to it.

And all Aquatics, that I know, have their Roots in the Earth, tho’ cover’d with Water.

The Pores, Cavities, or Interstices of the Earth, being of two Sorts, viz. Natural and Artificial; the one affords the Natural, the other the Artificial Pasture of Plants.

The natural Pasture alone will suffice, to furnish a Country with Vegetables, for the Maintenance of a few Inhabitants; but if Agriculture were taken out of the World, ’tis much to be fear’d, that those of all populous Countries, especially towards the Confines of the frigid Zones (for there the Trees often fail of producing Fruit), would be oblig’d to turn Anthropophagi, as in many uncultivated Regions they do, very probably for that Reason.

The artificial Pasture of Plants is that inner Superficies which is made from dividing the Soil by Art.

This does, on all Parts of the Globe, where used, maintain many more People than the natural Pasture; and in the colder Climates, I believe, it will not be extravagant to say, ten times as many: Or that, in Case Agriculture were a little improved (as I hope to shew is not difficult to be done), it might maintain twice as many more yet, or the same Number, better.

The extraordinary Increase of St. Foin, Clover, and natural Grass, when their Roots reach into pulveriz’d Earth, exceeding the Increase of all those other Plants of the same Species (that stand out of the Reach of it) above One hundred Times, shew how vastly the artificial Pasture of Plants exceeds the natural. A full Proof of this Difference, (besides very many I have had before) was seen by two Intervals in the middle of a poor Field of worn-out St. Foin, pulveriz’d in the precedent Summer, in the manner describ’d in a Note on the latter Part of Chap. XII. relating to St. Foin. Here not only the St. Foin adjoining to these Intervals recover’d its Strength, blossom’d, and seeded well, but also the natural Grass amongst it was as strong, and had as flourishing a Colour, as if a Dung-heap had been laid in the Intervals; also many other Weeds came out from the Edges of the unplow’d Ground, which must have lain dormant a great many Years, grew higher and larger than ever were seen before in that Field; but above all, there was a Weed amongst the St. Foin, which generally accompanies it, bearing a white Flower; some call it White Weed, others Lady’s Bedstraw: Some Plants of this that stood near the Intervals, were, in the Opinion of all that saw them, increased to a thousand Times the Bulk of those of the same Species, that stood in the Field three Feet distant from such pulveriz’d Earth.

Note, These Intervals were each an Hundred Perch long, and had each in them a treble Row of Barley very good. The Reason I take to be this, That the Land had lain still several Years after its artificial Pasture was lost; whereby all the Plants in it having only the natural Pasture to subsist on, became so extremely small and weak, that they were not able to exhaust the Land of so great a Quantity of the (vegetable) nourishing Particles as the Atmosphere brought down to it.

And when by Pulveration the artificial Pasture came to be added to this natural Pasture (not much exhausted), and nothing at all suffered to grow out of it for above Three Quarters of a Year, it became rich enough, without any Manure, to produce this extraordinary Effect upon the Vegetables, whose Roots reached into it. How long this Effect may continue, is uncertain: but I may venture to say, it will continue until the Exhaustion by Vegetables doth over-balance the Descent of the Atmosphere, and the Pulveration.

And what I have said of any one Species of Plants in this Respect may be generally apply’d to the rest.

The natural Pasture is not only less than the artificial, in an equal Quantity of Earth; but also, that little consisting in the Superficies of Pores, or Cavities, not having a free Communication with one another, being less pervious to the Roots of all Vegetables, and requiring a greater Force to break thro’ their Partitions; by that Means, Roots, especially of weak Plants, are excluded from many of those Cavities, and so lose the Benefit of them.

None of the natural Vegetable Pasture is lost or injured by the artificial; but on the contrary, ’tis mended by being mix’d with it, and by having a greater Communication betwixt Pore and Pore.

But the artificial Pasture consists in Superficies of Cavities, that are pervious to all Manner of Roots, and that afford them free Passage and Entertainment in and thro’ all their Recesses. Roots may here extend to the utmost, without meeting with any Barricadoes in their Way.

The internal Superficies, which is the natural Pasture of Plants, is like the external Superficies or Surface of the Earth, whereon is the Pasture of Cattle; in that it cannot be inlarg’d without Addition of more Surface taken from Land adjoining to it, by inlarging its Bounds or Limits.

But the artificial Pasture of Plants may be inlarg’d, without any Addition of more Land, or inlarging of Bounds, and this by Division only of the same Earth.

And this artificial Pasture may be increas’d in proportion to the Division of the Parts of Earth, whereof it is the Superficies, which Division may be mathematically infinite; for an Atom is nothing; neither is there a more plain Impossibility in Nature, than to reduce Matter to nothing, by Division or Separation of its Parts.

A Cube of Earth of One Foot has but Six Feet of Superficies. Divide this Cube into Cubical Inches, and then its Superficies will be increas’d Twelve times, viz. to Seventy-two Superficial Feet. Divide these again in like Manner and Proportion; that is, Divide them into Parts that bear the same Proportion to the Inches, as the Inches do to the Feet, and then the same Earth, which had at first no more than Six Superficial Feet, will have Eight hundred Sixty-four Superficial Feet of artificial Pasture; and so is the Soil divisible, and this Pasture increasable ad Infinitum.

The common Methods of dividing the Soil are these; viz. by Dung, by Tillage, or by both.