VIII. TILLAGE OPERATIONS
When the natural green sward, or ground that has been cleared of a cultivated crops, is to be prepared for the sowing or planting of further crops, the plough leafs the way in breaking up the compact surface, by cutting from it successive slices, averaging about ten inches in breadth by seven in depth, which it turns half over upon each other to the right-hand side. This turning of the slices or furrows to one side only rendered it necessary to square off the space to be ploughed into parallelogram, half the slices of which are laid the one way and the other half the other, by the going and returning of the plough. These parallel spaces are variously termed ridges, stetches, lands, or feirings, which in practice vary in width from a few furrows to 30 yards. When very narrow spaces are used, a waste of labour ensues, from the necessity of opening out and then reclosing an extra number of index or guiding furrows; while very wide ones involve a similar waste from the distance which the plough must go empty in traversing at the ends. The spaces thus formed by equal numbers of furrow-slices turned from opposite sides have necessarily a rounded outline, and are separated by open channels. In a moist climate and impervious soil, this ridging the surface causes rain-water to pass off more rapidly, and keeps the soil drier than would be the case if it was kept flat. Hence the cultivated lands of Great Britain almost invariably exhibit this ridged form of surface. Until the art of under-ground draining was discovered, this was indeed the only mode of keeping cultivated ground tolerably dry. But it is at best a very defective method, and attended by many disadvantages. When land is naturally dry, or has been made so by thorough drainage, the flatter its surface is kept the better for the crops grown upon it. We are not forgetful that there are, in various parts of Great Britain, clays so impervious that probably no amount of draining or disintegration of the subsoil will render it safe to dispense with ridging. These, however, are exceptional cases, and, as a rule, such a condition of soil and subsoil should be aimed at as will admit of this rude expedient of ridging being altogether dispensed with. Unless land can absorb the whole rain which falls up in it, its full range of fertility cannot be developed; for the same showers which aggravate the coldness and sterility of impervious and already saturated soils carry down with them, and impart to those that are pervious, ever fresh supplies of genial influences. Instead, then, of this perennial source of fertility being encouraged to run off by surface channels, or to stagnate in the soil and become its bane, let provision be made for its free percolation through an open stratum several feet in thickness, and then for its escape by drains of such depth and frequency as each particular case requires. When this is attained, a flat surface will generally be preserved, as alike conducive to the welfare of the crops and to the successful employment of machinery for sowing, weeding, and reaping them.
In all treatises on British agriculture of a date anterior to the first quarter of the present century, we find great stress laid on the proper formation of the ridges, careful cleaning out of the separating channels or water-furrows, and drawing and spading out of cross-cuts in all hollows, so that no water may stagnate on the surface of the field. As through under-draining makes progress, such directions are becoming obsolete. But whether ridging or flat work is used, the one-sided action of the plough renders it necessary, in setting about the ploughing of a field, to mark it off into parallel spaces by a series of equi-distant straight lines. Supposing the line of fence, at the side at which he begins, to be straight, the ploughman has this as his base line; and measuring from it, erects his three or more feiring poles perfectly in line, at a distance from the fence equal to half the width of the ridges or spaces in which it is proposed to plough the field. This operation --- called in Scotland feiring the land --- is usually entrusted to the most skillful ploughman on each farm, and is regarded as a post of honour. Having drawn a furrow in the exact line of his poles, which practice enables him to do with an accuracy truly admirable, he proceeds, using always the last furrow as a fresh base from which to measure the next one, until the field is all marked off. When this is done, it presents the appearance of a neatly ruled sheet of paper. Besides the poles just referred to, the ploughman is frequently furnished with across staff, by means of which he first of all marks off two or more lines perpendicular to the straight side at which he commences, and along these he measures with his poles, which are graduated for the purpose, in laying off his parallel lines. This feiring is only required when a process of fallowing, in preparation of green crop, has obliterated the former ridges. In breaking up clover lea or older sward, the ploughman begins at the open furrows, which afford him a sufficient guide.
In ploughing for a seed-bed the furrow-slice is usually cut about five inches deep. In the case of lea, it should be turned over unbroken, of uniform thickness, and laid quite close upon the preceding one, so as to hide all greensward. The improved wheel-plough already referred to does this work very beautifully, cutting out the slice perfectly square from the bottom of the furrow. The perfect uniformity in the width and depth of the slices cut by it permits the harrows to act equally upon the whole surface. When the slice is cut unevenly, they draw the loosened soil from the prominence into the hollows, so that one part is scraped bare, and the other remains untouched and unbroken. This must necessarily yield a poor seed-bed, and contrasts unfavorably with the uniform tilth produced by harrowing after such work as these wheel-ploughs invariably produce. In the Lothians and west Scotland, a form of plough is much used for ploughing lea, which cuts out the slice with an acute angle at the land side. This, when turned over, stands up with a sharp ridge, which looks particularly well, and offers a good subject for harrows to work upon. But if a few of these furrow-slices are removed, the firm earth below exhibits the same ribbed appearance as the newly ploughed surface, instead of the clear level sole on which the right-angled slice cut by the wheel-plough is laid over so as to rest upon its lower angle. This ribbing of the unstirred subsoil is exceedingly objectionable in all kinds of ploughing.
In the autumn ploughing of stubble-ground in preparation for the root-crops of the following season, a much deeper furrow is turned over than for a seed-furrow. In ordinary cases it should not be less than nine inches, while in very many, if ten or twelve can be attained so much the better. In all deep soils this bringing up and mixing with the surface of fresh material from below is highly beneficial. It must not, however, be practiced indiscriminately. Siliceous and peaty soils need compactness, and to have the soil that has been artificially enriched kept a-top. For such deep work as we have noticed above, three or even four horses are frequently yoked to the plough. When a field slopes considerably one way, it is good practice to work the plough down the slope only, and return without a furrow. A pair of horses working in this way will turn as deep a furrow, and get over as much ground, as three will do taking a furrow both ways, and with less fatigue to themselves and to the ploughman. After bringing a heavy furrow downhill, they get recruited in stepping briskly back with only the plough to draw. This mode of ploughing one furrow down the slope tends less to gather the soil toward the bottom than by using a turn-wrest plough across the slope. It is while giving this deep autumn furrow that the subsoil plough is used. It follows in the wake of the common plough, and breaks and stirs the subsoil, but without raising it to the surface. This is a laborious operation, and engrosses too much of the horse-power of the farm to admit of large breadths being overtaken in any one season. In all indurated subsoils, however, it repays its cost; for when once thoroughly done, it diminishes the labour of ordinary ploughing for several succeeding rotations, aids the drainage, and adds to the fertility of the soil. It is in the performance of this deep autumn tillage and breaking up of the subsoil, which the steam-engine, with appropriate tackle, has begun to play an important part, and for which it will probably one day supersede all other means.
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