Preparation of' the land.—As a rule, very deep plowing is not best for sweet-potatoes. The com mercial demands are for a short, thick root as nearly round as possible, and deep preparation, though increasing the total yield, tends to make long roots. On the average, five or six inches may be regarded as the proper depth, although seven inches would answer very well ; some growers pre fer to plow only three or four inches. The plowing should be done shortly after the land comes into condition in the spring ; as the sweet-potato is an intensive money crop, it is often possible to select the most favorable time for plowing for this crop. When the soil reaches a certain condition, neither too wet nor too dry, it crumbles nicely before the plow and harrows down into a fine garden condition. Since the sweet-potato plants have to be trans planted into the soil, specially fine preparation is required. It is seldom safe to postpone the harrow ing of sweet-potato land. A spike-tooth harrow should be run over the land the same day that it is plowed, thoroughly pulverizing the surface. In certain very light sandy soil best adapted to sweet potatoes, the preparation is so simple and easy that no special care is required. But many sandy soils have enough clay in them to bake and form clods, and hence need careful attention.
After the field is plowed and harrowed, the fertil izer can be drilled in, or sown broadcast if it is desired to make a large application. The writer uses 1,200 pounds per acre, 800 pounds of which is drilled in after the harrowing. This is done prefer ably at least two weeks before planting, so that, if possible, one or two rains will intervene, thor oughly dissolving and diffusing the caustic parts of the fertilizer. If there is a rain sufficient to wet down the plowed land, and this is particularly desir able at this time, as soon as the soil comes into condition it is thoroughly and deeply harrowed with a disk-harrow or one of the cutaway or spading harrows. The disk is then followed either at once or in a short time by the acme, spike-tooth or some surface pulverizing harrow. Land in this condition, finely pulverized and full of moisture, is ready to resist any reasonable drought, and the plants can be set out in all but the most intensely dry weather. A week or two before planting time, furrows three to five inches deep should be run with a one-horse plow. The distance may be three feet six inches to four feet, or even slightly more. In these fur rows, 400 pounds per acre of commercial fertilizer is applied. This can be put in most economically with one of the little distributers of the wheel barrow type. The manure can then be distributed in the bottom of the furrow. The quantity of manure naturally varies ; the average would be a strip four inches wide and one inch deep. If the manure is light and strawy, of course the depth would be greater.
In applying such a quantity of manure an average forkful reaches three or four feet in the drill, and the amount used per acre is about eight tons. The manure can be applied previous to plowing. It may be spread on crimson clover sod in the fall, with excellent results, or it may be distributed on the ground in the winter. Care should be taken, how
ever, not to haul heavy loads over the land when it is very wet. Most sweet-potato-growers prefer to put the manure in the furrow under the crop. The greater economy of fall and winter distribution in labor and teams is an argument for the latter method. If possible, the drills should be opened, the fertilizer and manure applied and then a ridge bedded over the fertilizers by a one-horse plow the same day, unless the soil is very moist. In dry weather it is also necessary to bed up the ridges several days before planting, while in a tolerably moist time planting can proceed at once after bedding.
Starting the plants (Figs. 839-841).— While the preparation of the soil is in progress, the propaga tion of the plants should be proceeding. Sweet potato plants can be purchased in quantity, and some growers prefer to buy them from men who make a business of growing the plants. Formerly, in the southern states parts of the sweet-potato roots were sometimes cut and planted after the method commonly used for Irish potatoes. As a rule, however, plants are grown in the hotbed, pulled from the potatoes when they are the proper size and transplanted into the field. The propagation of these plants in the hotbed becomes one of the important features of the growing of this crop.
Ordinarily, the small potatoes, three-fourths inch to about one and three-fourths inches in diameter, are stored separately and are used as seed-roots. Generally the seed-roots are saved from the ordinary crop and more or less selection is practiced by choos ing the short, smooth shapely roots, or, at any rate, by rejecting the misshapen, ribbed or crooked pota toes. "Slip-seed" is generally preferred to "seed roots " saved from the crop. This is produced by tak ing cuttings from young vines, varying in length from eight to ten inches up to twenty inches, and thus avoiding fungous diseases which are carried over on the roots. "Slip-seed" is also supposed to be more vigorous and productive. Usually "slip-seed" may bring nearly double the price of ordinary "seed roots." This is particularly true in New Jersey, Maryland and elsewhere, where propagation from cuttings is not so easy as it is further south where there is a longer season. In the South, it is not unusual for a man who is to plant ten acres of sweet-potatoes to bed a barrel or two of roots, plant a couple of acres and then make cuttings for the remainder of the crop. These cuttings may consist of two or three joints of the vine with a single leaf on the upper joint, or, possibly, of a longer piece. When short cuttings are used they are set out just like plants, leaving the single leaf and bud above ground. When longer cuttings, a foot or two in length, are used, the cutting is usually planted about half its length in the ground. Some growers use a long cutting and loop it, put ting both ends in the ground. These cuttings can be planted out in moist weather the same way as plants, and in a favorable "season" appear to leaf and root almost as well as rooted slips.