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The '''potato''' is a [[starch]]y, [[tuber]]ous [[crop (agriculture)|crop]] from the [[perennial plant|perennial]] ''[[Solanum]] tuberosum'' of the [[Solanaceae]] family (also known as the nightshades). The word potato may refer to the plant itself as well as the edible tuber. In the region of the [[Andes]], there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food crop, following [[rice]], [[wheat]], and [[maize]].<ref>http://www.hort.purdue.edu/rhodcv/hort410/potat/po00001.htm</ref>
The '''potato''' is a [[starch]]y, [[tuber]]ous [[crop (agriculture)|crop]] from the [[perennial plant|perennial]] ''[[Solanum]] tuberosum'' of the [[Solanaceae]] family (also known as the nightshades). The word potato may refer to the plant itself as well as the edible tuber. In the region of the [[Andes]], there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food crop, following [[rice]], [[wheat]], and [[maize]].<ref>http://www.hort.purdue.edu/rhodcv/hort410/potat/po00001.htm</ref>
Potato plants are herbaceous [[perennial]]s that grow about 60 cm (24 in) high, depending on variety, the [[culm (plant)|culms]] dying back after flowering. They bear white, pink, red, blue, or purple [[flower]]s with yellow [[stamen]]s. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins.<ref>[http://books.google.com/books?id=QDrqL2J-AiYC&pg=PA209&dq=potato+plants+60+cm&client=firefox-a Growing Food: A Guide to Food Production] ISBN 1402066244</ref> Potatoes are [[pollination|cross-pollinated]] mostly by [[insects]], including [[bumblebee]]s, which carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.<ref>[http://www.ijdb.ehu.es/abstract.01supp/s37.pdf Regulation of potato tuberization by daylength and gibberellins]</ref>
Potato plants are herbaceous [[perennial]]s that grow about 60 cm (24 in) high, depending on variety, the [[culm (plant)|culms]] dying back after flowering. They bear white, pink, red, blue, or purple [[flower]]s with yellow [[stamen]]s. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins.<ref>[http://books.google.com/books?id=QDrqL2J-AiYC&pg=PA209&dq=potato+plants+60+cm&client=firefox-a Growing Food: A Guide to Food Production] ISBN 1402066244</ref> Potatoes are [[pollination|cross-pollinated]] mostly by [[insects]], including [[bumblebee]]s, which carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.<ref>[http://www.ijdb.ehu.es/abstract.01supp/s37.pdf Regulation of potato tuberization by daylength and gibberellins]</ref>
After potato plants flower, some varieties produce small green fruits that resemble green [[cherry tomato]]es, each containing up to 300 true [[seed]]s. Potato fruit contains large amounts of the toxic [[alkaloid]] [[solanine]] and is therefore unsuitable for consumption. All new potato varieties are grown from seeds, also called "true seed" or "botanical seed" to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit float). Any potato variety can also be [[vegetative propagation|propagated vegetatively]] by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce [[seed]]s at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".
After potato plants flower, some varieties produce small green fruits that resemble green [[cherry tomato]]es, each containing up to 300 true [[seed]]s. Potato fruit contains large amounts of the toxic [[alkaloid]] [[solanine]] and is therefore unsuitable for consumption. All new potato varieties are grown from seeds, also called "true seed" or "botanical seed" to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit float). Any potato variety can also be [[vegetative propagation|propagated vegetatively]] by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce [[seed]]s at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".
Solanum tuberosum, Linn. Potato. Low, weak-stemmed, much-branched perennial with tender, herbaceous tops, and perpetuating itself asexually by means of thickened or tuberous underground sts., glabrous or pubescent-hirsute: lvs. unequally pinnate, the 5-9 oblong-ovate lfts. interposed with much smaller ones: fls. variable in color, white passing through various tints and shades of purple, violet, and blue, in long-stemmed dichotomous clusters: fr. a globular berry 1/2- l in. or more in diam., usually through lack of viable pollen not produced in the highly developed modern varieties except in favored localities and in the case of certain varieties, but fruiting abundantly in S. Chile and in Peru. Temp. Andes of Peru and Bolivia. See Potato.
Solanum tuberosum, Linn. Potato. Low, weak-stemmed, much-branched perennial with tender, herbaceous tops, and perpetuating itself asexually by means of thickened or tuberous underground sts., glabrous or pubescent-hirsute: lvs. unequally pinnate, the 5-9 oblong-ovate lfts. interposed with much smaller ones: fls. variable in color, white passing through various tints and shades of purple, violet, and blue, in long-stemmed dichotomous clusters: fr. a globular berry 1/2- l in. or more in diam., usually through lack of viable pollen not produced in the highly developed modern varieties except in favored localities and in the case of certain varieties, but fruiting abundantly in S. Chile and in Peru. Temp. Andes of Peru and Bolivia. See Potato.
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Potato. One of the most widely utilized and valuable of esculent tubers, produced underground as thickened stems. It is commonly known as the "Irish," "white," or "round" potato to distinguish it from the sweet potato; botanically it is Solanum tuberosum. See Solanum.
The potato is one of the most universally cultivated plants of the United States and Canada, and it is becoming increasingly important as an article of human food. It ranks sixth in agricultural importance in the United States. This country produces, however, only about one-fifth as much as Germany. This is due to the fact that the German consumption of potatoes per capita is about two and a half times as great as ours, and that more than 50 per cent of the German crop is used either for stock-food or for conversion into starch, alcohol, or other industrial by-products. Potatoes, at present, are used very little for these purposes in this country, less than 1 per cent being so used.
The potato is closely allied, botanically, to several powerful narcotics, such as tobacco, henbane, and belladonna, and also to tomato, eggplant, and capsicum. Potatoes contain a small amount of a somewhat poisonous substance. When exposed to the direct rays of the sun and "greened," the deleterious substance is so greatly increased that the water in which they are boiled is not infrequently used to destroy vermin on domestic animals. In any case, the water in which potatoes are cooked should not be used in the preparation of other foods.
The potato is a native of the elevated valleys of Chile, Peru, and Mexico, and a form of it is found in southern Colorado. It probably was carried to Spain from Peru early in the sixteenth century. It seems to have been introduced into Europe as early as 1565. Sir Walter Raleigh, in 1585, is said to have brought back the potato from the "new country." Recent investigations, however, seem to give the credit of introducing the potato into England to Sir Francis Drake, in 1586. As Batatas virginiana, it was figured and described by Gerarde in 1597. It is probable that these circumstances led erroneously to giving the credit of introducing the potato to Raleigh instead of to Sir John Hawkins. The wild varieties in their native habitat still bear a close resemblance to cultivated varieties except for the enlarged vine and abnormal development of the tubers in the latter. In the seventeenth century the potato was cultivated in gardens in several European countries. It was recommended by the Royal Society of London in 1663 for introduction into Ireland as a safeguard against famine. The cultivation of the potato as a field crop became somewhat common in Germany soon after 1772, at which time the grain-crops failed and potatoes were a welcome substitute for the bread-corn. It was near the middle of the eighteenth century before it acquired any real importance in Europe, outside of Ireland and a few restricted localities in other countries. As late as 1771 only a white and red variety were mentioned in one of the most important English works on gardening.
The plants were enormously productive, but the tubers were poor in quality, so poor in fact that their chief use was as a food for domestic animals; and only when the bread-corns failed were they used to any extent, and even then only as a substitute. By 1840 the potato had been largely substituted in Ireland for the cereals and other similar food-crops, as the yield of potatoes in weight exceeded by twenty to thirty times the yield of wheat, barley, or oats on an equal area of land. This large dependence on a single food-crop finally resulted in a wide-spread famine. The potato blight which appeared in the United States in 1845 devastated Ireland in 1846. During two years, 1846 and 1847, a conservative estimate places the numbers who perished for want of food or from diseases caused by a meager diet of unhealthy and unnutritious food at 600,000. By 1848 the plague had virtually disappeared.
The roots of the potato are distinct from the tubers. Usually, two to four roots start from the stalk at the base of each underground stem which, when enlarged at the end, forms the potato. (See Fig. 3152.) Roots may also start where underground stems are wanting. The potato is a perennial plant. The accumulated starch in the tubers furnishes an abundant supply of nourishment for the plants growing from the eyes or buds until they are well above the ground. So much food is stored that not infrequently small young tubers are formed on the outside of the potatoes left in the cellar during the summer. Potatoes grow from 2 to even 3 feet high, have smooth, herbaceous stems, irregularly pinnate leaves, and wheel-shaped flowers, varying in breadth from 1 to 1 1/2 inches and in color from bluish white to purple. They bear a globular purplish or yellowish fruit or seed-ball of the size of a gooseberry, containing many small seeds. As many as 297 seeds have been found in a single seed-ball.
The cultivated potato of today has undergone a remarkable change since its first introduction into Europe by the Spaniards. Some of this change has been brought about by better cultivation, but most of it is due to breeding. The tubers of the wild S. tuberosum were small and attracted little attention. Heriot, in his report on Virginia, describes the plant "with roots as large as a walnut and others much larger ; they grow in damp soil, many hanging together as if tied on ropes." The modern potato has been bred so that the hills contain four to six tubers of uniform size, weighing, perhaps, two pounds. (See Fig. 3153.)
The uses of the potato are wide and varied, but taking the world over, its greatest value is as a food-crop. It is probably eaten by a greater proportion of the earth's inhabitants than any other crop except rice. It is extensively used for the manufacture of starch. The great potato-growing sections of the United States, especially Aroostook County, Maine, have many starch factories, where the tubers which are oversize or under- size or otherwise not fitted for ordinary food purposes are converted into starch. The price ordinarily paid for potatoes for starch-making is considerably less than that for eating, and unions the price for eating gets
very low, good marketable tubers are not used for starch. The potato has many other uses which have been much less developed in the United States than in Europe, but there is a rapidly increasing tendency for their uses in the arts here. It is used in the textile industries, in the manufacture of woolen, linen, and silk goods; for the manufacture of potato flour, glucose, syrup, candy, desiccated potatoes for food, industrial alcohol, mucilage, dyes, stock-feed, and so forth.
The dry matter of potatoes is composed largely of starch. A high starchy content is desirable because it makes a mealy potato which is demanded in America. Being deficient in nitrogen, the potato is ill adapted for an exclusive diet and should be used in connection with food containing a high percentage of proteids, such as lean meat, peas, beans, and eggs. The lack of vegetable fats may be supplied by butter, gravy, or oatmeal. The composition of the potato varies widely.
The nutritive ratio of wheat is 1 to 5.37, almost perfect; that of potatoes 1 to 18.29, much too wide. Many foods in their natural state, as potatoes, are more or less deficient in mineral matter. Notable among these are rice and wheat flour ,the former containing but 0.4 per cent and the latter 0.5 per cent of ash.
The main potato industry in the United States is confined to several potato-growing sections in widely separated parts of the United States. The most important of these are Aroostook County, Maine; the Norfolk and Eastern Shore trucking regions of Virginia and Maryland; the Red River Valley of Minnesota and North Dakota; the Kaw Valley of Kansas; the Greely and Carbondale districts of Colorado; the Twin Falls country of Idaho, and the San Joaquín and Sacramento valleys of California. In these regions, the climate and soil are perfect for the best potato- production.
Varieties.
There are many hundred varieties of potatoes. The older varieties run out in the course of time and are supplanted by new ones. The running out is largely due to the fact that growers, as a rule, do not practise seed-selection. The new varieties are ordinarily produced either from hybridized seed or from bud-sports. The latter are somewhat common. Red tubers are now and then found in white hills, and vice versa. Other differences are taken advantage of by breeders.
Of the many varieties listed in seedsmen's catalogues and found on the market, however, only a very few are of commercial importance. Fitch, of the Iowa State College, has made a thorough trial for a number of years of all varieties of commercial importance in the Unites States and Europe. He also made a canvass in person and by letter of the markets of the United States. The result was that only a few varieties were found to be of much market value. He lists the following varieties as being the most valuable in the United States in order of their importance: Rural New Yorker, Green Mountain, Early Ohio, Burbank, Irish Cobbler, Bliss Triumph, Peerless (Pearl). Many other varieties, of course, have local importance and perhaps outyield the standard varieties named above.
New varieties are being produced constantly, a very few of which may prove to be better than the standard sorts, but most of them are worthless.
William Stuart, of the United States Department of Agriculture, has recently made a very comprehensive and admirably arranged classification of potatoes, as follows :
Group 1. Cobber.
Tubers: Roundish; skin creamy white. Sprouts: Base, leaf- scales, and tips slightly or distinctly tinged with reddish violet or magenta. In many cases the color is absent. Flowers: Light rose- purple; under intense heat may be almost white.
Group 2. Triumph.
Tubers: Roundish; skin creamy white, with more or less numerous splashes of red, or carmine, or solid red; maturing very early. Sprouts: Base, leaf-scales, and tips more or less deeply suffused with reddish violet. Flowers: Very light rose-purple.
Group 3. Early Michigan,.
Tubers: Oblong or elongate-flattened; skin white or creamy white, occasionally suffused with pink around bud-eye cluster in Early Albino Sprouts: Base light rose-purple; tips creamy or light rose-purple. Flowers: White.
Group 4. Rose.
Tubers: Roundish oblong to elongate-flattened or spindle- shape flattened; skin flesh-colored or pink, or (in the case of the White Rose) white. Sprouts: Base and internodes creamy white to deep rose-lilac; leaf-scales and tips cream to rose-lilac. Flowers: White in sections 1 and 2; rose-lilac in section 3.
Group 5. Early Ohio.
Tubers: Round, oblong, or ovoid; skin flesh-oolored or light pink, with numerous small, raised, russet dots. Sprouts: Base, leaf-scales, and tips more or less deeply suffused with carmine-lilac to violet-lilac or magenta. Flowers: White.
Group 6. Hebron.
Tubers: Elongated, somewhat flattened, sometimes spindle- shaped; skin creamy white, more or less clouded with flesh-color or light pink. Sprouts: Base creamy white to lilac; leaf-scales and tips pure mauve to magenta, but color sometimes absent. Flowers: White,
Group 7. Burbank.
Tubers: Long, cylindrical to somewhat flattened, inclined to be slightly spindle-shaped; skin white to light creamy white, smooth, and glistening, or deep russet in the case of section 2. Sprouts: Base creamy white or faintly tinged with magenta; leaf-scales and tips usually lightly tinged with magenta. Flowers: White.
Group 8. Green Mountain.
Tubers: Moderately to distinctly oblong, usually broad, flattened; skin a dull creamy or light russet color, frequently having russet-brown splashes toward the seed end. Sprouts: Section 1 base, leaf-scales, and tips creamy white: section 2 base usually white, occasionally tinged with magenta: leaf-scales and tips tinged with lilac to magenta. Flowers: White,
Group 9. Rural.
Tubers: Broadly round-flattened to shortroblong, or distinctly oblong-flattened; skin creamy white, or deep russet in the case of section 20. Sprouts: Base dull white; leaf-scales and tips violet- purple to pansy-violet. Flowers: Central portion of corolla deep violet, with the purple growing lighter toward the outer portion; five points of corolla white, or nearly so.
Group 10. Pearl
Tubers: Round-flattened to heart-shape-flattened, usually heavily shouldered; skin dull white, dull russet, or brownish white in section 1 or a deep bluish purple in section 2. Sprouts: Section 1 base, leaf-scales, and tips usually faintly tinged with lilac; section 2 base, leaf-seal , and tips vinous mauve. Flowers: White.
Group 11. Peachblow.
Tubers: Round to round-flattened or round-oblong; skin creamy white, splashed with crimson or solid pink: eyes usually bright carmine. Includes some early-maturing varieties. Sprouts: Base, leaf-scales, and tips more or less suffused with reddish violet. Flowers: Purple.
Cultivation of potatoes.
The best soil for potatoes is a sandy loam, well drained but provided with an abundant supply of water. If the soil is deficient in moisture, the water from rainfall must be conserved by shallow cultivation. The ground should be plowed deeply and worked thoroughly so as to bring about perfect aeration. Whether the plowing should be done in the fall or the spring will depend largely upon the distribution of time and labor which the grower has at his disposal, except that hilly fields which are likely to wash during winter should not be plowed in the fall.
In cutting potatoes for planting, each eye should be supplied with an abundance of food to start the young plants vigorously. The pieces should be as large as possible and not bear more than piece two or three eyes. (See Fig. 3154.)
The potato is sensitive to frost, and therefore must complete its growth in most localities in three to six months. The period of development may be shortened by exposing the seed potatoes to the more or less direct rays of the sun in a temperature of about 60° for one or two weeks before planting. Some of the starch is transformed into sugar, which causes the eyes or buds to develop into miniature short tough plants or "rosettes" which results, when the potatoes are planted, in hastening growth and shortening the period between planting and harvesting. Some varieties, when thus treated in warm rich sandy soil, produce merchantable tubers in six weeks.
The kind and amount of fertilizer which should be applied to potatoes will, of course, vary with conditions, such as method of rotation, natural fertility of the land, methods of growing the crop and so forth. The best method of rotation is one in which a crop of clover immediately precedes the potato-crop, particularly in the North. This furnishes nitrogen and leaves the ground in good mechanical condition. Ordinarily, potatoes require a fertilizer analyzing about 4 per cent of potash, 7 per cent of phosphoric acid and 10 per cent of potash. If lime is applied to the land during the rotation, it should follow the potatoes and not precede them, as it furnishes the best conditions for the development of scab, which is a serious disease. The same is true of wood-ashes which, ordinarily, contain 30 per cent of lime.
Potatoes are planted either by hand or with a machine. Good-sized tubers should be cut into about four pieces and a single piece placed in each hill. The seed-pieces should be planted soon after cutting so as to prevent "bleeding or loss of water from the cut surfaces. The depth of planting will depend upon circumstances, but ordinarily 4 to 6 inches maybe considered an average depth. The planting-machines are usually drawn by two horses and perform several operations at once. They open the furrow, distribute the fertilizer, cover it slightly so that it will not come into direct contact with the seed, drop the seed-pieces and cover them. Sometimes a heavy wheel, to act as a roller, is attached to the rear of the machine to pack the soil over the hills. By means of these machines, large acreages may be planted in a short time.
Potato fields should be given frequent and thorough tillage to keep down the weeds and conserve soil moisture. These cultivations should be shallow to prevent injury to the roots. The soil is cultivated until the plants are large enough nearly to fill the rows and have begun to "set" tubers. Further tillage is likely to injure the plants and reduce the yield.
After the plants are mature, the tubers are dug either by hand or with an elevator digger drawn by two or more horses.
Yields.
The yield of potatoes to the acre in the United States is meager, the average yield for the ten-year period 1900-1909 being 91.4 bushels. Under favorable soil and climatic conditions, with rational methods of procedure, 200 to 400 bushels are not uncommon, and under superior conditions more than 1,000 bushels to the acre have been secured. By dividing the eyes and planting them in the greenhouse in the winter, and after a little time re-dividing them, continuing this until many plants were secured, one grower was enabled to raise 2,558 pounds of potatoes in the open from one pound of seed, being an increase of more than 2,500 fold. Two other growers secured, by similar methods, 2,349 pounds and 2,118 pounds. The low average yield is due, in part, to the ravages of the many enemies of the potato plant, which, uncontrolled, sometimes destroy the crop, and usually seriously diminish the yield. In the United States, the potato is not so universally used or so productive as in Europe, though its use as a food is steadily increasing.
In common commercial culture, the yield as well as quality may be greatly enhanced by care in selecting seed. The progeny of two similar potatoes is shown in Fig. 3153, showing the inherited performance of the tubers.
The average annual production in the United States from 1881 to 1890 was 169,809,053 bushels, while the yield in 1913 was 331,525,000 bushels, which sold for an average farm price of 48.9 cents a bushel. New York stands first in potato-production, producing 53,215,000 bushels of the total yield. The crop of Europe aggregates more than the entire wheat-crop of the world. The production of the European countries for 1913 was:
France, 477,111,000; Austria, 424,457,000; Germany, 1,988,591,000; Russia, 1,274,439,000; the United Kingdom, 283,912,000 bushels. In 1912 the United States exported 76,382,000 bushels and imported 80,134,000 bushels.
Enemies.
The most common enemy to the potato plant, the Colorado potato-bug, is easily destroyed by applications in a powder or in a liquid of paris green or arsenate of lead to the vines when the bugs first appear. The fungus, Phytophthora infestans, causes the true blight (Fig. 3155), which results in potato-rot. The true blight may be kept in check by frequent and thorough sprayings with bordeaux mixture. It is always well to incorporate arsenicale with the mixture, that any remaining bugs may be destroyed. The bordeaux mixture is also useful in protecting in part the plants from the flea-beetle. Two or three applications are usually made during the summer. The early blight is more common than the true or late blight. It causes the shriveling and death of the foliage (Fig. 3155). It is usually the combined result of several causes, chief amongst which are fungi, flea-beetle, drought. Thorough good care and spraying with bordeaux mixture are the best treatments. A good potato field is shown in Fig. 3156 (adapted from "American Agriculturist"); and the picture also shows a good hand-praying rig.
Potatoes as a market-garden or truck crop.
The chief difference between potatoes as a field crop and a market-garden or truck-farm crop is that in the former case they are grown in rotation with other long- season plants and consequently may occupy the ground for the entire growing season, while in the latter they occupy the ground only a few weeks and are usually preceded and followed by some early or late garden crop the same year. In the North the crop is usually grown in the spring and early summer, but in the South it may be grown either in the early spring or late fall. The spring crop is grown to supply the demand for new potatoes in the early markets while prices are high, but the fall
crop is mostly consumed locally either for table purposes or for seed for the next spring crop. In the trucking region of the upper South, the spring crop is planted in January, February, or March and harvested in May and June, and the fall crop in July or August and harvested in October or November.
The favorite Virginia rotation starts with potatoes planted in February and harvested in June. Cowpeas are sown immediately for a summer cover-crop; these are plowed under in August as a means of improving the soil, and spinach is planted in September. This crop is harvested in January or February and garden peas are planted in rows 5 or 6 feet apart. The peas are inter- planted in late March with cucumbers. The peas are harvested in April and May, and the cucumbers in June and July. The ground is planted to kale in August, which is harvested in midwinter and potatoes planted again in February or March. A second two year rotation starts with potatoes planted in February followed by cowpeas or an annual grass for forage. Winter cabbage is transplanted to the field in November or January. Corn is planted after the cabbage is harvested in May or June. Cowpeas are planted between the rows of corn at the last working. The cornstalks remain standing in the field until late fall when the grain is harvested and they and the pea-vines are worked into the ground to supply organic matter.
Since earliness, productiveness, and reasonable resistance to disease are the main requisites for truck- farm potatoes, the varieties that meet the requirements are limited. In the South Atlantic and Gulf states, Bliss Triumph is the leading variety, while in the Carolinas and Virginia, Irish Cobbler is the favorite; but in the upper Mississippi Valley, Early Ohio undoubtedly is in the lead.
Seed grown in Maine, Michigan, Wisconsin, or other northern states will produce potatoes of marketable size five to ten days earlier than locally grown seed. Consequently truck-farmers who wish to cater to the early market depend upon the northern tier of states for their seed-supply; but those who wish to sell on the midseason market are now largely using locally grown seed. Plants from northern-grown seed suffer more severely from certain diseases than do those from local seed, hence the extreme earliness of the crop from the northern seed is, to a marked degree, compensated for by the healthier vines and larger yield from local seed.
The seed-stock to be used in producing the home or locally grown seed is obtained from the North in the winter or early spring, and held in cold storage until July or August, when it is planted. The tubers are harvested after the vines are killed by frost in October or November, and are placed in farm storage until needed for planting.
The land should be broken with a turn-plow a month or six weeks in advance of planting the potatoes, if the preceding crop in the rotation will admit. It is best to apply the stable-manure to some preceding crop in order that it may be well decayed before the tubers are planted. After the ground is thoroughly harrowed, the rows should be marked out about 3 feet apart. If drainage is not good it is well to open the furrow with a small turning-plow in order to expose a large surface to the action of the sun, air, and frost. A few days before planting, the furrows should be reopened, the fertilizer required distributed in them. It should be thoroughly mixed with the soil to prevent its coming into direct contact with the seed-tubers when they are planted.
In forcing potatoes, especially in the cooler season of the year, it is customary to use from 1,500 pounds to 2,000 pounds of fertilizer analyzing 5 to 6 per cent nitrogen, 6 to 7 per cent phosphoric acid, and 5 per cent potash, to the acre. The potatoes will not use all of this, but that remaining after they are harvested is available for subsequent crops. About one-third of the nitrogen in the fertilizer should be obtained from nitrate of soda and sulfate of ammonia and the other two- thirds from high-grade tankage, blood, and fish-scrap. By using nitrogen from the sources mentioned, the plants are enabled to obtain a constant supply throughout their growing-season. The phosphoric acid is obtained from acidulated South Carolina rock, and the potash, preferably, from sulfate of potash. Some growers apply about 1,000 pounds of the fertilizer in the rows before the tubers are planted and the balance as a side or top dressing when the plants are well started.
Whether the potatoes are to be planted by hand or a power planter, it is better to apply the fertilizer before planting, as much better distribution may thus be obtained. The larger number of truck-farmers follow the practice of hand planting, but the larger growers are now using horse-power machines. From three to five barrels of northern-grown seed and from two to three barrels of home-grown seed are usually required to plant an acre. The seed-pieces are placed 14 to 16 inches apart in the rows and are usually placed from 2 to 4 inches below the surface-level of the ground. The hand-planted tubers are covered by turning two furrows over them with a small turn-plow, thus forming a ridge 8 or 9 inches high above the tubers. If the discs of the power planter do not form such ridges, it is customary to add additional soil with the plow. These high ridges protect the seed-tubers against unfavorable weather conditions and enables them to develop strong roots before the sprouts appear above the ground, thus insuring rapid development when the season opens.
As soon as the tubers have formed sprouts an inch or two long, a light harrow is dragged diagonally across the ridges to kill any weeds that may be starting, and to provide a mulch over the row. A second dragging is given a week or ten days later, or just before the sprouts appear above the surface. The first working with the cultivator is given as soon as the plants have the row well outlined; subsequent cultivations are given at intervals of a week or ten days, a small quantity of soil being worked against the plants, thus forming low ridges at the later cultivations. If proper attention is given to the early cultivation, little or no hoe work need be expected.
The season for harvesting depends more upon market conditions than upon the maturity of the crop. If prices are high, digging may be started when the yield will not be over thirty or forty barrels to the acre, but if prices are moderate with indications for a steady demand, harvesting may be delayed for two or three weeks. In the meantime the yield will have increased from 25 to 50 per cent.
The crop is usually turned out of the ground with a plow while the vines are still green. The vines are then pulled out of the ground with most of the tubers attached. These are carefully pulled from the roots, the others picked out of the loose soil and placed into piles on the ground. They are then graded by hand and packed in barrels for shipment. Great care is used in handling the new potatoes to prevent unnecessary bruising.
Mechanical diggers have not given satisfaction in the trucking region of the South, primarily because they bruise and break the skin, thus causing the tubers to present discolorations when placed on the market.
Potato, air: Dioscorea bulbifera. P. Onion: Onion. P., Sweet: Sweet Potato, and Ipomaea Batatas.
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