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Continuation of the Account of the Compleat Body of Husbandry; with Remarks. See Vol. XVII, page 406.

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ANY of our Readers may, poffibly, think us fome. what tedious in the confideration of the Treatife before us; but when the vaft importance of the fubject, and the high expectations which have been artfully raifed, as to the merit of this compleat work, are duly confidered, we flatter ourfelves, any further apology will be deemed unneceffary.

We are now arrived at the fixth book of the Compleat Body of Husbandry; which treats of Tillage, in fix parts, viz.

ift, Of Plants, and their Nourishment.

2. Of the Advantages of Tillage.

3. Of the Implements of Husbandry, and their several Ufes,

Of the different Manners of Sowing.

4.

5. Of Drill and Harfehoeing Husbandry.

6. Of the Benefits of Drill and Horfehoeing Husbandry.

The first part treats, 1ft, of Roots. Their forts(1); the extent to which they fometimes run; either perpendicularly (2),

(1) Which are two; fpreading roots, and tap roots.

(2) They fay, that the firft roots of every feed are always of the perpendicular kind; and in foft deep foils will penetrate many yards into the earth, if uninterrupted: which we really believe, if they are not too short.

VOL. XVIII.

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or horizontally; their tendency towards the furface of the ground (3); the advantage which the often firring that surface produces, in increafing their quantity, and caufing them to spread to a great extent (4): and that heat is a great article in

the process of roots of plants obtaining their nourishment.' For, by its conftant variation, contracting and expanding, it "gives motion and preffure between the roots and the fmall particles of earth continually,—and is, indeed, the true fource of the nourishment and growth of vegetables."

2dly, Of Leaves. We are told that these are the organs of transpiration, and are fo neceflary to the greateft part of vegetables, that they cannot fubfift without them; for if all the leaves of a flourishing tree are pulled off, it will commonly die. That, from the number of veficles filled with air contained in leaves, many have concluded them to be the lungs of plants; and Mr. Papin's experiments, it is faid, feem to favour this doctrine. Plants tranfpire only in the day:-during the night they revive, and' by their leaves, imbibe the dews and rains,' which contributes greatly to their growth.'

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There are many more curious obfervations here, collected chiefly, it seems, from Grew, Papin, Tull, and Du Hamel.

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3dly, Our Authors treat of the Nourishment of Plants; and beflow five chapters in endeavouring to prove, that all plants are nourished by the fame fubftance: that this fubftance is no other than earth in very fine particles, carried into their veffels by water?' that it there undergoes that change which gives it the particular taste, colour, and form, ⚫ which belong to the plant;' which is evident from the com· mon effects of grafting trees.'-An inftance of Mr. Du Hamel's in the Memoirs of the French Academy proves this, it is faid, in a very particular manner. A young citron, of

the bignefs of a pea, was let in by the stalk to a branch of an orange tree. The citron grew to its full bignefs, and became perfectly ripe, but was, to all intents and purposes a citron; having nothing of the orange at all in its nature, form, taste, or appearance. Further, that every plant will exhauft the earth of its [that] nourishment which would be fit for others of the fame growth.' And that a piece of land which was once fit for the nourishing and fupporting of a crop of any plant,

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(3) Caufed by the effect, they say, of the rains, and dews, and influence of the fun's rays: which alio makes them grow to a greater ¡ength.

(4) This is illuftrated by an experiment from Mr. Tull.

will continue to fupport and nourish crops of that plant for ever, if it be properly tilled and managed, &c.'

Thefe opinions are acknowleged to be Mr. Tull's; and our Authors not only approve, but have farther fupported them by experiments and authorities, from Mr. Hales, from Du Hamel, and from common obfervations(5); and, to our apprehenfions, with great truth and reafon. This very curious fubject, is here largely difcuffed, and well explained.

4thly, of Changing Crops, and of the Distribution of the Nourishment of Plants in the Earth.

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Here our Authors obferve, that though there is a great advantage in fowing fucceffively different fpecies upon the fame land, yet this is not owing to the commonly fuppofed caufe, that each exhausts the earth only of its peculiar nourifhment, leaving the proper juices for the others.' But the good effects of changing crops is, by them, attributed to three causes; ft, the different quantity of nourishment different plants require; 2d, the different conftitution and formation ' of' parts in plants, fome being much more delicate than • others;' 3d, the different quantity of tillage which each kind '-requires'(6). Thus poor land will nourish rye, but not

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(3) One of our Author's obfervations is, that Wheat, requiring a great deal of nourishment, fucceeds better after Oats than after Barley; because Oats exhauft the ground lefs than Barley. Now here, if we appeal to experience, we believe our Authors will be found miftaken, in fuppofing that Wheat fucceeds better after Oats than after Barley, and that the former exhauft the ground lefs than the latter. For generally, in the compafs of our knowlege, where Wheat is fown on flubbles, they are almost always either bean or pea ftubble, on heavy land; or Barley ftubble, on light dry land: but rarely, we had almost faid never, Oat ftubble on any fort of land. For it is the general opinion of Farmers, that no grain impoverishes ground like Oats and it is a general rule with them, when about leaving a farm, to fow a great many Oats, to get, as they fay, their pennyworths out of the ground.

And the nature of the Oat feems to confirm the truth of the Farmers opinion, for it is a hot, hardy plant, which is feen by its growing, and even delighting, in cold climates, as the Highlands of Scotland, &c. and wet foils, as the Fenns, &c. And it is the moft fibrous rooted plant of any common grain that grows by which it is properly qualified to gather the great quantity of food its hot conftitution, strong digeftion, and fituation in fuch cold climates, and wet foils, requires.

(6) Thefe three caufes feem to be needlefsly wire drawn out of each other; for, to our underflanding, they appear to be no more B z 2

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wheat, nor, they fay, oats(7). And oats will penetrate hard land better than barley, and, therefore,-will grow with lefs llage,' &c.

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Take a fmall fpecimen of our Authors manner of accounting for the infertility of foils. When the pores [of a Soil] are in too fmall number,' they fay, there is, frequently, no communication between them; and the roots are thus ftopped in their pas

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age, and cannot get at the nourishment that is ready for them in other places, nor obtain enough for the fupport of the plant: this is the fault of too fiff foils. On the other hand, when the pores are too large, the roots go through them almoft without touching the earth, they, therefore, can take no nourishment from it: this is the fault of too light foils. Thefe are the defects of the generality of foils, and thefe may be remedied by culture properly conducted: for the earth contains fo great a quantity of nourishment, that there is no need to fear exhaufting it; the only bufinefs is to put the roots in a condition of getting at it.' Well, Gentlemen, and when you have remedied thofe defects by culture,' that is, when you have increafed the pores of fiff foils, and made thofe of light foils fmaller; and thus put the roots into a condition of getting that great quantity of nourishment,' you fay, the earth contains; you will ftill have only flow, inactive, earth; which will do but little towards vegetation, until a proper degree of heat be introduced, even according to your own account, in Chap. HI. of this part, that heat is the true source

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of the nourishment and growth of vegetables.' Nor yet, will fire and earth of themfelves fuffice for vegetation; the other two elements, air and water, muft join their good offices, or nothing can be done, after all. In fine, to forward vegetation, in the higheft degree, it feems requifite, there should be a proper conjunction of all the four elements(8), in fuch due and proportional quantities, as the peculiar nature and conflitution of the particular fpecies of plants require. And that land is the richest

than this, that different plants having different conftitutions, and texture of parts, require different quantities of nourishment, and, of courfe, different degrees of tillage.

(7) We cannot agree with them in this, because we know that the wort land, if it will bear any thing, will bear Cats: which, by their conflitution, and by the fructure and make of their roots, as obferved before, are better fitted to live on the pooreft foils, than any other common grain.

(8) We have, here, nothing to fay to the artificial elements of the Chemifts, and Cartefians: we want only thofe plain fimple ones of Nature, Fire, Water, Earth, and Air, to explain the principles and phænomena of vegetation.

which has the greatest share of all these four elements, in futh due proportion to each other as the nature of the particular ipecies of plants to be nourished, requires.

Therefore, land may be poor, i. e. afford but little nourishment to plants, in two refpects. Ift, It may have a large thare of all the four elements conjunctly, but in fuch an undue proportion to each other, as is most unfuitable to the particular Ipecies of plants to be nourished. So clays have a large fhare of earth and water; but too little heat and air: and gravels and fands, have a large fhare of heat and air; but too little water and earth. 2dly, Land may have too small a share of all the elements conjunctly. As chalk has too little of fine earth; for it is compofed of a coarfe dry earth that will not enter the veficis of plants; for plants will not grow on it: too little of air; too little of fire, for it has no heat in it: too little of water, for it lets that through like a fieve. Such, we apprehend, with due fubmiffion, is the nature of chalk (9).

Now a due proportion of manure(10) actually fupplies plants with these elements, and conveys them to their roots. For the fermentation of the manure causes a beat, or gentle fire (the first element) in the earth, which divides and pulverizes it(11), in the fame manner with tillage, tho' in a much greater degree; and thus produces fine earth, (another element) which our Authors call, and which is, indeed, the primary part of the food of plants. Again, this heat and fermentation occafions a rarefaction of the air contained in the earth, and in the roots of the plants; this causes the internal air to expire, and the external to infpire, and thus produces a circulation which fupplies the plant with a continued fucceffion of fresh air, (a third element). Laftly, The falts contained in manure, that are lodged at or near the furface of the ground, attract the dews, by cooling the ambient air, which condenfes and precipitates the vapours flot ing in it; and thus, perhaps, in no finall measure, fupplies the

(9) These are, we believe, all the entire pure foils we have; and, we humbly conceive, that most of our other foils, are only a compound of fome, or all of thefe. But our confined limits will not allow us to perfue this theory any further at prefent.

(9) This due proportion is well known to the experienced Hyfbandman.

(11) It is probable, that the fermentation, by its agitation and intef tine motion, breaks and divides the earth into a great number of small congeries of parts; and that the heat, by rarefying the air contained in each, again fubdivides every part; fo that their joint effect in pulverizing the ground, is, no doubt, much greater than that of tillage ean be.

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