TEXAS AGRICULTURAL EXPERIMENT STATION C. H. McDOWELL, Acting Director College Station, Texas' BULLETIN NO. 668 APRIL 1945 STUDIES ON SWEET POTATO PRODUCTION IN TEXAS R. E. ‘VRIGHT Division of Horticulture AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS GIBB GILCHRIST, President ' E53-445-8M-L180 ; 791 _ LIBRARY > kn: hgrssuitaraifwfifiesfiaiszisaé §@§§@a£,e@i‘§exas [Blank Page in Original Bulletin] Successful sweet potato production is largely the result of care ' in following methods known to give good results. These include the selection of roots to secure potentially productive seed of high quality, measures to control diseases, early planting, the use of adequate fertilizers, clean early culture, care in handling the roots and so on. Such things have been discussed simply and briefly so that East Texas growers will have a ready source of informa- tion in regard to practices now recommended. More complete reports of the experimental work will be made available later.‘ Selected References . . CONTENTS Acreage and Production . . . . . . . . . . Varieties and Strains . . . . . . . . . . . .. Selection of Seed Stock Seed Treatment .. Plant Growing Preparation of Soil and Cultivation Rotation . . . . . . . . . . . . . . . Fertilization . . . . . . . . . . . . . . . . . . . . . Time of Planting, and Spacing . . . Harvesting . . . . . . Storage ..». . . . . . . . . . . . . . . . . Utilization of Gulls and Vines . . . . . Acknowledgment Qulonanooalooaooo oalloouolnei i TlIDIES ON SWEET POTATO PRODUCTON METHODS IN TEXAS By R. E. Wright, Horticulturist?‘ In Charge of Sweet Potato Investigations Laboratory, Gilmer, Texas. V Acreage and Production sweet potato is one of the best liked and most valuable vegetable y produced in Texas. Its high nutritive value is widely recognized. i? ‘ crop is easily grown, and can be used as a fresh vegetable throughout 7 ~ late summer months as well as in cured form with nearly equal value five or six months in storage. For these reasons sweet potatoes are A- ted on the majority of the farms in the sandy soil areas of Texas. monetary value of the sweet potato crop in Texas for 1943 was ced at $12,074,000 by the United States Crop Reporting Board. The ‘L? as acreage for 1943 was estimated at 72,000 as compared with 64,000 1944. Acreage of this crop could be greatly expanded if economic f itions justified the increase. e to its high vitamin and food content and the ease with which it can Iprocessed the sweet potato has acquired added prominence during the emergency. The various government agencies have purchased millions ounds of fresh, canned, and dehydrated sweet potatoes for our armed “yes and our allies. A shortage of carbohydrate feeds in Texas has ulated interest in converting culls into livestock feed by sun drying artificial means. The sweet potato as a source of commercial “alcohol ld not be overlooked. i“ n» most cases it is not practical for the average farmer to increase his f t potato acreage. Therefore, if increased production is to be secured most economical procedure would be to increase the average yield [the acreage normally grown. A study of the problems affecting yields Sheen underway at the Sweet Potato Investigations Laboratory in Up- p“ County, since 1938. - Varieties and Strains ye Porto Rico as represented by its various strainsis the most popular ety grown in the State. This variety is popularly known as a “Yam” use of its moist flesh. Typically, the Porto Rico is characterized ts copper-red skin and salmon-pink flesh. It is a good eating potato first harvested as well as after curing, which makes it suited to both and late markets. ing the seven year period, 1938 through 1944, more than 400 varieties, >8 'ngs, or selections have been grown from seed stock secured from us sources. In addition to these lots, several thousand new seedlings grown from true seed. C. . A1. It is interesting to note from this table that several varieti‘ 6 BULLETIN NO. 668, TEXAS AGRICULTURAL EXPERIMENT STA'1‘I0 ~ * Representative data on yields from ten varieties are presented 1 yield the ‘Porto Rico, but they are suitable only for feed or indust ' l_ poses. Of all the varities tested to date only the Porto Rico can be A mended for the table stock market. Table 1. Sweet Potato Variety TestJ-Three-year Average, 1940-1942 (Fertilizer—600 lbs. 4-8-10 per acre.) Yield in bushels per acre Variety Jumbo U.S. No.1 U.S. No. 2 Culls Big Stem Jersey . . . . . . . . . . . . . . .. 0 31.8 43.6 74.4 Nancy Hall . . . . . . . . . . . . . . . . . . .. 7.0 45.1 141.2 58.3 Triumph . . . . . . . . . . . . . . . . . . . . . . . 9.9 65.9 134.0 82 8 Unit 1 Porto Rico* . . . . . . . . . . . .. 20.6 55.0 166.6 40.5 Texas Porto Rico* . . . . . . . . . . . . .. 14.6 51.9 154.7 59.2 - 96 . . . . . . . . . . . . . . . . . . . . . . . . .. 88.2 44.7 174.1 85.2 B-219 . . . . . . . . . . . . . . . . . . . . . . . . .. 10.8 97.0 161.5 95.2 L-4-5 . . . . . . . . . . . . . . . . . . . . . . . . .. 17.1 30.5 157.0 80.2 Maryland Golden* . . . . . . . . . . . . . . 0 27.8 50.6 43.2 Wenholz 1 . . . . . . . . . . . . . . . . . . . .. 11.6 45.9 173.4 85.7 “Two-year average. ' Experiments have shown that as much variation in yield can pected between various strains of Porto Rico as between the Po and other varieties of sweet potatoes. Table 2 shows that some strains outyield others by 40 percent. figures for only one season, supported by the additional data avi are very strong evidence that yields can be increased significantly if lowing rigid seed selection practices. ~ Table 2. Comparison of Yields of Strains of Porto Rico Sweet Potatoes, 194 Yield in bushels per» acre Strain Jumbo U.S. No.1 U.S. No.2 Culls s Hill 10, 1938 . . . . . . . . . . . . . . . . . .. 5.0 174.4 170 8 117.3 S. Jordan . . . . . . . . . . . . . . . . . . . . .. 13.0 110.9 109 4 86.8 Texas Porto Rico . . . . . . . . . . . . . .. 18.5 89.6 169 1 73.-l Red Velvet . . . . . . . . . . . . . . . . . . . .. 3.6 75.4 176 4 65.0 Arnold . . . . . . . . . . . . . . . . . . . . . . . .. 0.0 72.8 158 9 101.0 La. Unit 1 . . . . . . . . . . . . . . . . . . . .. 5.3 68.5 211 5 47.4 Porto Orado . . . . . . . . . . . . . . . . . . .. 0.0 66.3 180 7 53.6 , 8 . . . . . . . . . . . . . . . . . . . .. 0.0 65.0 106.6 38.3 Texas, 1938 . . . . . . . . . . . . . . . . . . .. 9.9 50.0 188.4 79.7 Selection of Seed Stock There are a number of factors essential to the successful prodg of sweet potatoes. Seed selection is among the most important of The common practice of selecting small potatoes from the storage in the spring without regard to the behavior of the parent plant w: tendency to reduce yields and results in “running out” of the strain a " STUDIES ON SWEET POTATO PRODUCTION IN TEXAS 7 ever, most growers must produce plants from sweet potatoes which they have on hand. To comply with State Certification requirements, all seed potatoes must be smooth, free from breaks, cracks, crooks, bruises, decay or disease signs, and insect pest damage. They must be at least one and one-half inches in diameter and at least three inches in length. Seed potatoes meeting these requirements can be further improved by selecting for uniform salmon-pink flesh color. Flesh color can be readily determined by cutting out a small chip not over 1/4 inch deep from the shoulder of the potato near the end by which it was attached to the plant. This process is referred to as “nicking”. Only those potatoes having the desired interior flesh color should be used for bedding. Immediately after selecting and “nicking” the seed stock should be disinfected and bedded. This process should be continued each year as sweet potatoes tend to mutate to a white color. The size of roots used for seed purposes has some effect on yield and grade as shown in table 3. Table 3. Size of Seed—Three-year Average (1938-1940) Yield in bushels per acre Size of root used for slips Jumbo U.S. No. 1 U.S. No. 2 Culls Total Jumbo . . . . . . . . . . . . . . . . . . . . . . . .. 2 2 62.9 30.5 45 1 140 7 U. S. No.1 . . . . . . . . . . . . . . . . . . . .. 0 9 52.9 27.5 512 132 5 U. S. No.2 . . . . . . . . . . . . . . . . . . . .. O 4 49.8 23.4 48 9 1224 Turnip shape . . . . . . . . . . . . . . . . . .. 2 5 50.8 23.7 46 0 123 0 Strings (under ll/g-lll.) . . . . . . . . . .. O 9 43.1 25.9 45 6 115 4 Increases in yield obtained from the use of good seed stock would more than offset the increased cost. Good seed stock can be checked for in- terior color more satisfactorily than can the small roots. The size or shape of seed stock has little effect on the shape of roots ' produced in the subsequent crop, as indicated by the data in table 4. Table 4. Comparison of Shape From Diiferent Size of Seed Average, inches Size of roots used for slips Length Diameter L_/D Ratio Jumbo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.33 2.31 2.74 = U.S. No.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.14 2.27 2.70 : U.S.No.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5.95 2.26 2.63 . Turnip Shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.10 2.33 2.62 i Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.65 2.31 2.88 Growers should make a special effort to grow and select good seed stock for large scale plantings. To avoid disease vine cuttings from selected seed stock should be planted on land not previously used for sweet pota- toes, and selection should be done at harvest. Hills having the largest 8 BULLETIN NO. 668, TEXAS AGRICULTURAL EXPERIMENT STATION number of uniform roots should be examined for disease, skin. and J color. Flesh color can be determined at harvest by clipping off the 1 {A end of the sweet potatoes thus eliminating the necessity of “nickingi; bedding time. This procedure does not materially damage roots for purposes if they do not meet seed stock standards. i Seed plots should be harvested earlier than commercial plantings. 1 published results indicate that early harvested sweet potatoes will duce the earliest slips as well as the highest number of slips per b Selected seed stock should be stored in new crates, or old crates '1; have been disinfected immediately before storing. A storage compart separate from the main storage house is desirable, and the temper should be maintained between 50 and 55 degrees F with high re 1; humidity. " Seed Treatment Seed disinfection is essential for successful sweet potato growing. though no disease is evident, the spores causing soft rot and black; may be present on the skin, since both diseases are common where potatoes are stored. Disinfection can be accomplished satisfactorily corrosive sublimate- or Semesan Bel, both materials being approvedf.‘ the State Department of Agriculture for certification purposes. l“ If corrosive sublimate is used, seed potatoes should be soaked 8 minutes in a solution made by dissolving four ounces of corrosive subl in 3O gallons of water. A stock solution can be conveniently made 4, placing 4 ounces of the corrosive sublimate -in a one-half gallon glass adding just enough hot water to make a paste, then filling the jar hot water while stirring with a wooden paddle. This half gallon of s,’ solution is then stirred into 30 gallons of water in a non-metal conta” After each 10 bushels of potatoes treated add one-half ounce of corr_ sublimate, or one-half pint of the stock solution and enough water; restore the solution to its original volume. The solution should be carded after treating about 50 bushels. In the case of larger tanks,» proportions should be the same. CAUTION: All containers must be}. wood, glass, or stone ware. Corrosive sublimate is a deadly poison should be handled accordingly. ll The Semesan Bel treatment is faster and easier to use, and appa, ly is just as ‘effective as corrosive sublimate for controlling diseasesf,‘ drum or tub, equipped with a drain board to prevent loss of the solu is satisfactory equipment-for average operations. The sweet potatoes ‘ 1 transferred to a wire basket, dipped into the solution for one minute, '5 then allowed to drain before bedding. One pound of Semesan Bel in‘; gallons of water is sufiicient for treating 75 bushels of seed potatoes. solution should then be discarded, the dipping containers cleaned, and“ new solution prepared. STUDIES ON SWEET POTATO PRODUCTION IN TEXAS 9 Plant Growing From 8,000 to 12,000 plants are required to set an acre, depending upon the width of the rows and spacing in the drill. A bushel of N0. 1 potatoes will require about 15 square feet of bed, and will produce from 1500 to 2000 slips during the entire season. When early plantings are desired, eight bushels should be bedded for each acre. However, if plantings are to be made until late in the season, from four to six bushels will be suf- ficient. Sweet potatoes should be placed close together in the bed, but should not touch. This is important since several diseases attack the seed potatoes and slips in the plant bed. i Many different types of beds are used for plant growing in this State. Seed potatoes bedded in the open usually produce slips around May 15, depending upon the season. For early plant production, some form of hot- bed should be used. Flue heated, steam or electric beds are all satis- factory. Small beds may be heated with shredded or chopped corn stalks, or any other organic material which will generate heat as it decomposes. The temperature of the bed should be held between 75 and 85 degrees F. Manure heated beds should be avoided if certification is desired, because they encourage diseases. The seed bed should be located in a well-drained, protected place, prefer- ably with a southern exposure. If the soil is likely to pack after heavy rains, old sawdust or sand can be used satisfactorily in the beds in place of soil. Commercial fertilizer or manure is not needed to produce healthy slips where good potatoes are bedded in a properly constructed plant bed. For early slip production, both electric and corn-stalk heated beds have been used. The corn-stalk method would be most practical and economical for the average grower. Table 5. Average Number of Slips Per Bushel of Seed Stock Source of Heat Year Electricity Corn-stalk No heat 1940 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1776 2230 . . . . . . . . . . . . 1941 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1366 1890 746 1942 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 1 673 547 1045 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1599 1449 788 1944 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1020 1787 573 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1338 1 806 664* *Four year average. lNote: The average current consumption on the electric bed was 27 per thousand p ants. Preparation of Soil and Cultivation Thorough preparation is essential for sweet potatoes, inasmuch as compact or unbroken soil retards down growth of the roots. The land should be selected as early as possible and organic matter plowed under suf- 10 BULLETIN NO. 668, TEXAS AGRICULTURAL EXPERIMENT STATION ficiently early to allow time for decaying prior to planting. This operation can be accomplished by flatbreaking, bedding or disking. Sweet potatoes grow off rapidly after setting in the field, requiring relatively few cultivations. Experiments at Gilmer have shown that the crop should be thoroughly cleaned and “laid by” as soon as the vines begin to run freely. Cultivation after this time has not increased yields, and operations which resulted in covering or breaking the vines reduced yields. Tests with different ridge heights were conducted for five years. Results from these studies indicate that the height of the bed, or row does not materially affect the yield or grade of sweet potatoes, if the land has been thoroughly prepared. The type of implements used on the farm should be the determining factor as to the height of beds used. These results are being published elsewhere. Rotation The sweet potato plant is generally recognized as being a heavy feeder, and should not be grown continuously on the same land. In many cases sweet potato fields are pastured during the fall and winter when the soil is wet resulting in injury to the soil which is reflected in future crops. Yields can be increased by rotation and soil building practices, but such cover crops as vetch should follow sweet potatoes instead of being plowed under just preceding the crop. Damage from disease can be re- duced to a minimum when sweet potatoes are grown on the land only once in four or five years. Fertilization Fertilizer tests have been conducted at the Laboratory at Gilmer, for a seven year period. Rates of application ranging from 400 to 600 pounds per acre have proven most profitable, but increased yields were secured from rates up to 1000 pounds per acre even during dry seasons. On sandy soils, 4-8-8 will probably give the best results, but 4-12-8 and 6-10-7 are also satisfactory. Time of application studies on Bowie fine sand show that the entire amount can be profitably applied before planting, if the fertilizer is thoroughly mixed in the drill before bedding. This procedure lessens the possibility of the roots of the slips being injured by coming in direct contact with the fertilizer. Plants set immediately following bedding will begin growth within a few days, and can be cultivated before grass and weeds become troublesome. Thus fewer cultivations will be required due to rapid vine growth. - Time of Planting and Spacing Date of planting studies show that highest yields may be expected when plants are set in the field as soon as danger of frost has passed. Plant- ings made more than four weeks after average date of the last killing frost STUDIES ON SWEET POTATO PRODUCTION IN TEXAS 11 show a significant reduction in yield. Early planting tends to produce chunky potatoes, making them less attractive for market purposes, but the increased yield usually more than oifsetsfthis difference in grade. N0 difference in shape or grade was evident when slips and vine cuttings were planted on the same date under similar fertilizer and soil condi- tions. Table 6 shows the effect of dates of planting on the yield of Porto Rico and Triumph sweet potatoes dug at the same time. Table 6. Effect of Time of Planting on Yield of Sweet Potatoes, 1940-1942 Acre yield in bushels Plantingi‘ Unit 1 Porto Rico Triumph 1st——April 15-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 315.7 311.7 2nd—April 30-May 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.5 316.9 3rd—May 15-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257.2 287.6 4th——l\/Iay 30-June 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.2 200.1 5th——June 15-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 160.9 173.8 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 .1 258.0 *The interval between plantings was about 15 days. ‘ Spacing studies carried on in connection with date of planting tests indicate that close spacings produce the highest yield of sweet potatoes. Spacing from 12 to 18 inches in three and one-half foot rows are most economical as indicated by results presented in table 7. Table 7. Efiect of Spacing on Yield of Sweet Potatoes, 1940-1942 Acre yield in bushels Spacing, inches _ _ Unit 1 Porto Rico Triumph 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268. 1 299.4 ‘ 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266.7 284.6 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256.9 273.8 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.6 262.8 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236.7 246.2 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.2 226.6 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214.3 212.7 Proper setting is just as essential as proper spacing. Extreme care should be exercised in setting to pack the soil firmly around the slips, thus eliminating airpockets. Poor stands and irregular growth is due more often to poor setting than to dry weather. Mechanical transplanters, ’ whether home-made or commercial, provide more uniformity in setting and makes subsequent cultivation easier. Harvesting Sweet potatoes should be handled like eggs or apples, and should not be thrown together in heap rows. If the sun is not too hot, the potatoes should be allowed to dry before they are handled. Persons handling sweet _ x w-wwwww-wwww-wh-s-w-wmrv-w- ' walls, and crates within the house. 12 BULLETIN NO. 668, TEXAS AGRICULTURAL EXPERIMENT STATION potatoes should use cotton gloves to reduce further injury due to handling. Grading should be done in the field and the sweet potatoes should be placed carefully in crates before hauling to the storage house. Bruised or cut roots do not keep well in storage, and such material should be fed to livestock as soon as possible, or sliced and dried for future use. A test designed to determine the effect of time of harvest (and other factors) on the yield of sweet potatoes was conducted for five years. Dur- ing the three-year period beginning with 1940, sweet potatoes were planted during the first half of May and harvested at approximately three-week intervals from the first week in September, with the final harvest being delayed until after the first killing frost. Table 8 indicates that yields increased approximately 20 percent during both the first and second intervals but no significant increase was recorded for the last interval. Table 8. Efiect of Time of Harvest on Yield of Porto Rico Sweet Potatoes Acre yield, in bushels Time of harvest 1940 1941 1942 Average 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 230.6 221.8 171.2 207.9 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 268.0 252.9 232.6 251.2 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 322.4 301.0 283.8 302.4 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 324.4 309.1 275.5 303.0 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286.4 271.2 240.8 . . . . . . . . . . If growth of vines is heavy, it may be necessary to cut them before plowing out the crop. In most cases a rolling coulter attached to the beam of a 12 inch turning plow will be found satisfactory for cutting and plowing in one operation. the entire row was built for operation on the tractor at the Laboratory during the 1944 season. See Texas Extension Service blueprint, Serial No. 308. This equipment eliminated most of the hand scratching, inas- much as approximately 90 percent of the sweet potatoes adhered to the vine when the plants were lifted from the soil by the main stem. Storage One of the most essential factors in successful sweet potato storage is sanitation in the storage house. Storage disease organisms live over from season to season on decayed sweet potatoes, as well as the floor, Prior to harvesting, the house should be thoroughly cleaned, and the interior walls, floor and crates disinfected with a formaldehyde solution (one pint formaldehyde to 30 gallons of water). The use of artificial heat for curing is normally unnecessary under East Texas conditions if the crop is harvested during October. Due to the length of time required for harvesting and filling a house, satisfactory A digger which cut the vines and lifted. UT"*IW="MW~ r v15?“ --. STUDIES ON SWEET POTATO PRODUCTION IN TEXAS 13 results will be obtained by opening the house during the day and closing it at night. Sweet potatoes are generally considered as being cured when they show indication of sprouting. If artificial heat is used, this condition can be brought about in a period of 7 to 10 days by main- taining a temperature of 85 degrees with high humidity. Curing is not necessary for the removal of excess moisture from stored sweet potatoes. Tests have shown that a part of the starch is converted to sugars, and the percentage of moisture in the sweet potatoes actually varies very little during the storage period. Harvesting causes some wounds to all sweet potatoes which must heal to resist organisms causing decay in storage. Conditions favorable for rapid curing are also ideal for the healing of wounds on sweet potatoes. Data presented in table 9 show that artificial heat for curing at Gilmer was uneconomical for the three-year period the storage tests were conducted. All lots of sweet potatoes were stored in the same house. The difference in shrinkage, which is in favor of the curing", is insufiicient to pay for the expense incurred. Table 9. Efiect of Curing on Shrinkage of Porto Rico Sweet Potatoes in Storage* Percent shrinkage based on harvest weight Treatment 1940 1941 1942 Average Cured 5 days at 85 degrees, before storage. . . . 14.6 9.8 10.2 11.5 Check-—harvested and placed directly in stor- age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13.9 10.4 12.4 12.2 *Average length of storage 140 days. Sweet potatoes should be stored after curing at 50 to 55 degrees F with a relatively high humidity. Rapid temperature changes will cause the con- densation of moisture on the walls and on the sweet potatoes, and should be avoided. A more uniform temperature can be maintained, even in warm weather, by keeping ventilators closed, especially during the day time. Utilization of Culls and Vines Sweet potatoes in their natural state are a satisfactory succulent feed for dairy cattle, beef cattle, horses and hogs. They have a feed value of 32% when compared with corn, thus requiring approximately three bushels to equal one bushel of corn. In the commercial market area of East Texas only the unmarketable roots can be used for commercial feeding. However, with an average corn yield of 1'0 bushels per acre, more carbohydrate feed per acre is usually available from cull sweet potatoes. In most cases storage loss and costs make it uneconomical to store culls for use at a time when they are most needed. 14 BULLETIN NO. 668, TEXAS AGRICULTURAL EXPERIMENT STATION Sweet potatoes can be sun dried for feed and stored in a dry place indefinitely without loss from decay or freezing. The dried material makes a carbohydrate concentrate which is practically equivalent to yellow corn chops in feed value, and can be safely fed to all farm livestock in place of corn. In preparing sweet potatoes for sun drying it is essential that they be cut instead of being ground in a hammer mill. A machine designed and constructed for use at the Laboratory cuts the cull roots in slices averaging 3/16 inch in thickness (Blueprint, Serial No. 273, Texas Extension Serv- ice). This equipment, built at a cost below twenty-five dollars, will cut two bushels of sweet potatoes per minute when powered with a 1 H. P. electric motor. ' The cut potatoes are spread on mulch paper, sheet iron roofs on low sheds, or specially prepared asphalt or oiled drying areas, at the rate of one pound per square foot of surface. With favorable weather conditions the sweet potatoes will dry in 48 hours. The pieces break when dry, or rattle when dropped on paper, and are then ready for storage. Ap- proximately two-thirds of the weight is lost in drying, requiring 300 pounds of sweet potatoes to produce 100 pounds of feed. The dried slices can be ground for feeding if desired. By using the digger referred to previously, sweet potato vines with l cull roots attached were converted into feed by the same method. This dry feed has the following analysis, per cent by weight: protein-—5.86, fat-—2.06, crude fiber—8.27, nitrogen-free extract—60.79, water 11.44 and ash—11.58. Utilization of this material for feed should increase the re- turns per acre considerably, and offers a source of badly needed feed. ACKNOWLEDGMENT The data reported in tables 1, 6, 7, 8 and 9 were obtained at the Texas Station as part of cooperative projects with the U. S. Department of Agriculture, Bureau of Plant Industry, Soils and Agricultural Engineering, Division of Vegetable crops and Diseases, and the Georgia, Louisiana, Mississippi and South Carolina Agricultural Experiment Stations and the Virginia Truck Experiment Station. STUDIES ON SWEET POTATO PRODUCTION IN TEXAS 15 SELECTED REFERENCES Beattie, J. H., and H. H. Zimmerley. Sweet Potato Growing, U.S.D.A. Farmers’ Bulletin N0. 999. 1932. Boswell, V. R. et al. Place and Season Effects on Yield and Starch Content of 38 Kinds of Sweet Potatoes. U.S.D.A. Circular No. 714. 1944. Hatter, L. L. Sweet Potato Diseases. U.S.D.A. Farmers’ Bulletin No. 1059. 1928. Miller, E. A. Sweet Potato Growing-Texas Extension Service, C-18. 1930. Miller, J. C. and W. D. Kimbrough. Sweet Potato Production in Louisiana. Louisiana Bulletin No. 281. 1936. Thompson, H. C. Storage of Sweet Potatoes. U.S.D.A. Farmers’ Bulletin No. 14.42.1925. Wright, R. E. Bedding and Planting Sweet Potatoes. Texas Agricultural Experiment Station—593 Progress Report. 1939. Wright, R. E. Sweet Potato Growing. Texas Agricultural Experiment Station, 662 Progress Report. 1940. Wright, R. E. Sweet Potato Growing. Texas Agricultural Experiment Station, 877 Progress Report. 1944. Wright, R. E. Processing Sweet Potato Vines with Attached Roots for Livestock Feed. Texas Agricultural Experiment Station, 923 Progress Report. 1945.