[212]’Tis certain that Turneps, when they stand for Seed, suck and impoverish the Ground exceedingly: For though they are of a cold Constitution, and consequently consume less Food than Plants of an hotter Constitution, and of the same Bulk; yet these Seed-turneps being of so vast a Bulk, as sometimes Eighty Quarters of their Roots grow on an Acre, and their Stalks have been measured Seven Feet high, and their Roots having continued at near their full Bigness for about Ten Months together, and then carried off, they drain the Land more than a Crop of other Vegetables of a less Bulk, and an hotter Constitution, and which live a less time; or than Wheat, which, though it lives as long, is very small, except in the Four last Months.
The true Cause why Clover and St. Foin do not succeed so well after their own respective Species, or that of each other, as Corn, &c. can, is, that they take great Part of their Nourishment from below the Plough’s Reach, so as that under Earth cannot be tilled deep enough, but the upper Part may be tilled deep enough for the horizontal Roots of Corn, &c. towards which, the Rotting of the Clover and St. Foin Roots, when cut off by the Plough, do not a little contribute[213]; And there’s no doubt but that, if the under Earth could be as well tilled for the Tap-roots, as the upper Earth is for the horizontal, the Tap-roots would succeed one another as well as the horizontal would succeed them, or those of their own Species, or as the Tap-roots do the horizontal.
[213]That the Rotting of vegetable Roots in the Ground doth ferment therein, and improve it for horizontal-rooted Plants, I am convinced by an Accident; viz. My Man had plowed off the Earth close to the Rows in a Field of extraordinary large Turneps designed for Seed. This Earth was neglected to be thrown back to the Rows, until a severe Frost in the Winter came, and killed the Turneps; upon which, in the Spring, the Field was sown with Barley upon the Level, with only once plowing, and that cross-ways of the Rows. The Turneps had stood so wide asunder, that the Spot whereon each had rotted, appeared like the Spot whereon an Horse had urined in till’d Ground, and was of a deeper Colour, and much higher, than the Barley that grew round those Spots; and yet none of it was poor. As the Roots of Clover, and St. Foin, are very much less; yet the greater Number rotting in plowed Ground must be of great Use to a following Crop of Corn.
I will here relate Two Examples of this in St. Foin: The one is, That a Field of Twenty-five Acres drilled with St. Foin, except Three Acres in the Middle of it, which was, at the same time, sown with Hop-Clover; after Eight Years the whole Field was plowed up by a Tenant, and sown with Corn: The St. Foin had been mowed yearly, as the Hop-Clover was not mowed at all, but fed by Horses teddered (or staked) thereon the First and Second Years; and after that had nothing on it but poor natural Grass.
The whole Field was managed alike, when plowed up; but the Three Acres produced visibly worse Crops of Corn than the rest all round it, which had produced St. Foin.
The other Example or Instance was, Where an Acre, Part of a Field, was, by a Fancy, drilled with St. Foin in single Rows, about Thirty-three Inches asunder, but was never hoed: After Seven Years it was plowed up with the rest of the Field cross the Rows, and sown with Oats upon the Back Three Months after plowing. These Rows were as visible in the Oats, as if the St. Foin had been still remaining there: The Oats in the Rows where the St. Foin had been, looked of a deep green flourishing Colour, at first coming up, and until they were about half a Foot high, and the Spaces between them looked yellowish; but afterwards the Difference of their Colour disappeared, all the Crop being very good. Upon this I imputed it to the Rotting of the Roots, which by their Singleness were very large; and when the different Colours disappeared, I suppose the Roots of all the Oats had reached to the Benefit of the rotted Roots, which might also be then spread farther into the Spaces; and I doubt not but that the Rotting of Broad Clover-roots has the same Effect as of St. Foin, for manuring of Land, especially when the Roots are large.
Some have objected against this Opinion, and say the Effect was rather to be imputed to the Rows of St. Foin shadowing the Earth under them, or else from their keeping the Earth under them free from Couch-grass, of which the Intervals were full: But I think it more probable, that the Couch-grass, having very long horizontal Roots, might draw Nourishment from the Earth under the Rows, and from the Intervals equally.
And as to the Shadow of the Rows, tho’, for the First and Second Years, the St. Foin Plants were very large; yet, being afterwards, for Five or Six Years, until plowed up, constantly fed by Cattle, and being more sweet, was eaten very low, whilst the Couch-grass remained intire in the Intervals, and shadowed them more than the Earth of the Rows was shadowed by the St. Foin: Besides, the rotten Turneps, which were freed from both these Objections, had the same Effect on the Barley, as the St. Foin had on the Oats.
The under Earth, in some time, is replenished by what the Rains leave, when they sink through it; and then Tap-rooted Plants may be there nourished again, tho’ the upper Earth be drained by the Corn; so that no Change is so beneficial, as that betwixt Tap-rooted Plants, and those which have only horizontal ones. The former are provided for by Rains, though not so speedily as the latter are by Tillage and Hoeing.
Pastures require no Change of Herbs; because they have annually the same Supply of Food from the Dunging of Cattle that feed on them, and from the Benefit of the Atmosphere.