The most approved modes of setting are as follows :—Drills should be formed in the well-pulverised field with double houtings of the plough, in order to have the shoulders uniform, which is essential to the correctness of succeeding operations. The dung is then to be carted out, and divided by the carter with a drag-fork as his horse and cart move forwards (the horse walking in the centre of three drills while the wheels move in the other two), in such quantities as can be most conveniently shaken out into the drills by the labourers employed to spread it. In dry weather the carting does no injury, and this method is universal in Scotland. The other principal mode, more generally pursued in Ireland by some of the best cultivators of the potato, is to cart out the manure before the drills are formed, in rows seven or eight yards apart, and to supply the drills from the heap*, as the plough advances in its work, reserving just as much as is supposed sufficient for the concluding drills, which are to be made in the sections of the field previously occupied by the rows of manure. By the latter treatment the manure may be laid over the sets—which cannot be clone in the former case—and this will preserve them from being displaced or crushed by the feet of the horses during the process of covering the seed. But against this advantage—which is not incon siderable—there is the inconvenience of calculating with precision and Laying aside as the plough advances to draw the last drills—where the rows had stood—the precise complement of manure, and the difficulty to tho ploughman of preserving the exact breadth in those drills.
Some avoid any perplexities in those respects by ploughing in the manure thoroughly before drilling,and either dropping the set in every third furrow, or rolling the whole manured and ploughed surface, and then making drills. Our own experience is greatly in favour of this latter mode, when the fertilising matter is abundant and of the short description which freely combines with the soil, and does not obstruct the plough in the subsequent drilling. The lazy-bed method is so generally condemned, that any explanation of it here would be super fluous, yet in undrained bog-land, or under any circumstances in which a redundancy of wetness is probable in the autumn, as on low marshy lands, or stiff clay soils which have no sufficient inclination to carry off the water, and are likely to be saturated with moisture in winter from want of drainage, the lazy-bed system is by far the safest. The deep wide furrows at each side carry off the water, or at least remove it from the potato. Thousands of tons of potatoes in the year 1839 were utterly lost in Ireland, being drilled in flat and tenacieuslands, which would have escaped destruction from the continued rains of that season if drained by the furrow of the lazy-bed. Besides, where cir cumstances preclude the practicability of deep ploughing, the lazy-bed practice repeated for three years will completely spade-trench the Entire land, and thus effect an important benefit not otherwise attain able by the humble tiller of the soil who has no teams for ploughing it effectually. Thus local or national modes, though apparently defective to the superficial observer, are sometimes founded upon sound principles, and though we feel disposed to exclude the minute details of what is only defensible under peculiar circumstances from an essay on potato culture under our modern system, we protest against the unqualified condemnation of a method which is still pursued through out a great part of Ireland.
The sets (uncut, for reasons to be yet assigned) are next, to be laid down, either under or over the manure, at the average distance of sixteen inches, by the setters, who move in a retrograde direction, and are provided with aprons to contain the seta. A sufficient number of men are in attendance to divide the manure evenly in the drills; the plough also is in the field in order that there may be the least possible exposure of the manure and sets to the sun or to parching wind, but the plough should cover the sets rather lightly in clay soil.
The roller is next used to lay an even surface to the brairding * plants, and to facilitate the subsequent progress of the paring plough, which is to be set to work when the stems are six or seven inches high, and should move as close to the plants as is practicable without injuring their tender fibres. The weeders should then hoe the plants carefully, and immediately afterwards (for the influence of wind or hot air on the roots is pernicious) the scuifier or drill-harrow is to follow, in order to clean and level the intervals, before the earthing plough, with either double or single mould-board, is introduced to apply fresh earth to the stems.
Such is the method of earthing universally pursued by the farmer in Ireland and Scotland, but in England the hand-hoe is principally used for destroying weeds, loosening the earth, and moulding the plants; for the two first of these operations the beau-hoe (which cuts about six inches deep) is used, and the turnip-hoe for drawing the earth to the stems. One man will hoe out the weeds and loosen the soil of half an acre per day, and the subsequent earthing of the same quantity is also executed by one man. This is far cheaper than horse work, and it does no injury to any of the stems, and makes no waste land at the headriggs ; and where the earth has been perfectly well prepared at the commencement, this manual husbandry is the best.
As to the distance between the drills, due regard must be had to the natural quality of the soil and the quantity and description of manure available, or in other words, to the probable luxuriance of foliage. Mr. Knight, aware of the necessity of allowing room in proportion to the vigour and height of the plants, has laid down an exact rule thus : —" The height of the stems being three feet, the rows ought to be four feet apart :" but for a general average, thirty inches is the best distance. As to excess of foliage, we are certain that it is not desi rable, for the produce of tubers is not always in proportion to the degree of foliage ; under high and rank stems there is often a very scanty crop, and Mr. Knight is justified by experience in his obser vation that " the largest produce will be obtained from varieties of rather early habits and rather low stature, there being in very tall plants much time lost in conveying the nutriment from the soil to the leaves," and consequently strong and upright stems, which do not fall down and shade the others, are those which are desirable.