bULEEIN- OF “ENE y USDEPARTHENT OFAGRICULTURE % No. 16 Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. October 225 1913. THE CULTURE OF FLUE-CURED TOBACCO. By E. H. MarHewson, Crop Technologist, Tobacco and Plant-Nutrition Investigations. INTRODUCTION. In its origin the flue-cured type of tobacco is associated closely with the old Virginia dark type and is really an offshoot from the latter, dependent primarily upon soil modification. Later the type was further modified and differentiated by cultural adaptations prompted by trade preferences. As the cultivation of tobacco in Virginia was pushed back to the lighter sandy lands of what is now the southern tier of counties of that State and the adjoining counties of North Carolina, the character of the tobacco produced was naturally some- what changed. It was milder and generally lighter in color and be- came popular for home consumption, particularly as a chewing to- bacco. It was preferred also by a certain class of the export trade, particularly in France, where the milder, lighter tobaccos were more popular. The dark Virginia tobacco was cured by means of open fires and smoke, which gave it a smoky, creosotic odor and flavor, This smoky flavor was objectionable to the trade desiring the milder to- bacco, and the use of open fires in curing was limited as much as pos- sible, and much of the product was merely air cured, fires being used only when necessary to protect it from damage in damp, muggy weather. Charcoal was often substituted for wood in order to keep down the odor of smoke. The use of charcoal grew to be the regular practice until, in turn, it was superseded by the use of flues, which came into use soon after the close of the Civil War. At first these flues were constructed of rock, but later they were made of sheet iron, as is the almost universal practice to-day. The use of flues still further did away with any tendency to smokiness and gave more uniformly satisfactory results in obtaining lighter and more uniform colors, as well as greater convenience in tending the fires. 6907° —Bull. 16—13. 1 2 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. Up to a time just before the Civil War, however, the production of this yellow type of tobacco was confined principally: to Caswell County, N. C., and Pittsylvania County, Va. The real development in the flue-cured type did not take place until during the decades immediately succeeding that in which the Civil War occurred, and on its present basis, therefore, it is essentially a modern type. A number of important and clearly defined factors are easily discernible as stimulating and promoting this development. From the standpoint of consumption, the demand was rapidly expanded by the growing popularity of pipe smoking in this country, for which this flue-cured type, in the form of granulated smoking tobacco, proved to be highly satisfactory, and also to the introduc- tion and rapid expansion in use of machine-made cigarettes. The greatly enhanced demand for tobacco of this type also extended to foreign countries, especially to Great Britain and certain of the British possessions. Supplementary to this great expansion in demand, resulting in good prices for the raw leaf, production was also markedly stimulated during this same period by the introduc- tion of commercial fertilizers, upon which the profitable production of flue-cured tobacco now so largely depends. By the middle eighties, therefore, the producing area and use of flue-cured tobacco had greatly enlarged and covered, as a crop of dominant importance, some 20 counties in the northern part of central and western North Carolina and in south central Virginia, thus embracing the Old Belt section about as it is known to-day. Prior to about 1890 little tobacco was grown east of Warren, Franklin, and Wake Counties, N. C. During the nineties the demand for flue-cured tobacco, especially of the brighter types, continued to expand, and in this same period the price of cotton was very low. This combination of circumstances resulted in a widely extended movement on the part of the farmers of eastern North Carolina and South Carolina to try tobacco growing where formerly attention had been given almost exclusively to cotton. So rapidly was the acreage expanded through- out this cotton-growing Coastal Plain section of eastern North Caro- lina and South Carolina, now known as the New Belt, that in 1903 this new section actually produced more tebacco than was grown in the Old Belt section. Because of this large production in the New Belt, the total crop of flue-cured tobacco of that year for both the New Belt and the Old Belt amounted to upward of 250,000,000 pounds, the largest crop produced up to the present time. This great crop year ushered in a period of lower prices, and production dropped off markedly in succeeding years, particularly in the New Belt, where attention was again turned to cotton, for which prices for several years were comparatively good. In 1911 and 1912 the flue-cured tobacco crop was considerably curtailed because of very a” 4c THE CULTURE OF FLUE-CURED TOBACCO. 3 unfavorable weather conditions, and prices for the brighter types of leaf again became very high, foreshadowing a greatly increased interest and expansion of acreage, more especially in the New Belt section, where the acreage and production fluctuate much more widely than in the Old Belt because of the opportunity for shifting between cotton and tobacco as conditions seem to warrant. At the present time, the normal annual production of flue-cured tobacco on a farm-weight basis is estimated to be about 215,000,000 pounds. Of this total about 120,000,000 pounds is produced in the Old Belt section and 95,000,000 pounds in the New Belt. The aver- age annual production of tobacco in the United States is now close to 1,000,000,000 pounds, of which the flue-cured type is approximately one-fifth. White Burley is the only other type that has had such a rapid expansion in production and popularity in so limited a period of years. As in the case of Burley, the rapid development of flue- cured tobacco is undoubtedly founded largely on its adaptability for meeting the popular demand for light, mild tobacco in the different forms in which it is consumed. All things considered, this flue-cured type of tobacco is unsurpassed in uni- versal popularity and general adaptability to a variety of uses, including granu- lated and cut smoking tobacco, both paper and all-tobacco cigarettes, and plug filer and wrapper; in fact, it is adapted to all the regular forms in which tobacco is used except standard cigars and snuff. In color and general appear- ance it is very attractive, while its low nicotine content, mildness, aromatic sweetness, fragrance, and good keeping qualities render it very satisfying to the user. It may also be noted that this type is the only one that has had any decided tendency to expand our exports in recent years. Of the total quantity of flue-cured tobacco produced, about 40 per cent, or around 90,000,000 pounds, is exported, and the remainder is used in domestic consumption. SOILS OF THE FLUE-CURED DISTRICT. Speaking broadly, the current trade differentiations of the flue- cured producing area into the Old Belt and the New Belt sections indicate also a fairly well-defined modification in the character of the tobacco produced in these two sections. The best tobacco soils of both the Old Belt and the New Belt are all light and sandy, but those of the New Belt, in the Coastal Plain, are lighter and more sandy as 2 class than are those of the Old Belt in the Piedmont sec- tion, and these soils, and especially the subsoils, become progressively 1¥or additional information concerning the general features of the flue-cured type, including a list of the counties producing flue-cured tobacco, with the estimated average quantity of tobaeeo preduced in each, see Bulletin 244, Bureau of Plant Industry, U. S. Department of Agriculture. 2U, S. Department of Agriculture, Bureau of Plant Industry, Bulletin 244, p. 70, 1912. 4 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE, more clayey as one progresses westward toward the mountains. The lighter Coastal Plain soils characteristically produce a brighter and paler type of leaf than the Old Belt soils, but with less body and richness. In the western part of the Old Belt, particularly from about Rockingham County, N. C., and Henry County, Va., the rich waxy filler types predominate, while the colors run in much larger proportion to mahogany or red. Soil adaptation is a very important factor in the production of a satisfactory quality of flue-cured to- bacco. It is an influence of fundamental importance in determining the color of the leaf produced, as well as such other points of quality as fineness, richness, and body. In general, the soils adapted to the production of flue-cured tobacco may be described as light and sandy to a depth of 6 to 10 inches, underlain with « sandy-clay subsoil of a yellowish orange color. The whiter soils produce the brightest tobacco, unless offset by some other factor. The clay of the subsoil is an important factor in giving the leaf richness and body, and it is also an aid in retaining fertility. In the Coastal Plain section some of the soils are such loose, deep sands as to constitute an extreme of the bright-tobacco type. Such soils will naturally produce a very bright tobacco, but the leaf is likely to be lacking in body and richness, and the soil itself is at a disadvantage in retaining fertility and is not likely to withstand wet weather well. On the other hand, the soils of the Old Belt section, more especially in the western part, frequently represent the other extreme of being too clayey and too red to pro- duce anything more than a dark tobacco, although, generally, the leaf will be rich and waxy. Between these soil extremes of the New Belt Coastal Plain section, some of them tending to be too ex- tremely sandy and open, and the clayey soils of the western part of the Old Belt section, there is to be found almost every conceivable variation in shade, depth, and mechanical structure. From a chemical standpoint, bright-tobacco soils are rather weak, as is to be expected from their high content of sand or silica, but most of them are very responsive to artificial enrichment by means of fertilizers, manure, and soil-improving crops. The relatively light souls which predominate in the New Belt section naturally are less well suppled with mineral plant food materials, particularly potash, than are the stronger soils of the Piedmont section. However, a soil possessing ideal mechanical and chemical qualifications may be en- tirely unsuited to tobacco unless it has good natural drainage, as it is ruinous to a tobacco plant to stand for any length of time in a water-logged soil. In the earlier days of tobacco culture, before commercial ferti- lizers came into general use, it was the almost universal custom to plant tobacco on “ fresh,” or recently cleared, land. On such land THE CULTURE OF FLUE-CURED TOBACCO, 5 there is an accumulation of readily available plant food; the tobacco grows quickly, matures and ripens early, and cures well. In the Old Belt, therefore, where much of the soil tends to be too strong and clayey, a given soil, perhaps, will produce a crop of good color and quality when it is “ fresh,” but will not do so after it has been under cultivation for a number of years. But in the case of the light soils in the Coastal Plain section, those which have been longer under cultivation are preferable because the “fresh” land will make the leaves too thin and lifeless and the bottom leaves will begin to waste away prematurely. CROP ROTATION SYSTEMS. Aside from the natural character of the soil itself, there is no more important matter for the tobacco grower to consider than the man- agement of his fields, so that in regular order they will be in the best shape for tobacco at the proper time. Indeed, the character of the tobacco produced will depend quite as much on how the fields have been handled in rotation between the successive tobacco crops as upon the fertilizer used or the cultivation given directly to the ‘tobacco crop itself. IMPORTANCE OF HUMUS IN THE SOIL. Tobacco Jand should be so handled as to be kept in good life. A liberal supply of vegetable matter in an advanced stage of decay is bighly desirable, but it should be of a kind not excessively rich in ammonia. For this reason the clovers, cowpeas, and other legumes, except in a limited way, generally can not be used with satisfac- tion preceding tobacco unless removed some two or three years from the tobacco, and on the stronger lands of the Old Belt seetion it would probably be best in most cases to omit them from the rotation altogether. Large quantities of slow-acting organic ammoniates tend decidedly against fineness, sweetness, and color. It is well known that the organic matter of freshly cleared or broom-straw fields is of a kind well suited to tobacco. It consists principally of dead leaves, twigs, roots, pine tags, or broom straw and roots. Such vegetable matter, while poor in ammonia, by its ample volume makes the soil very mellow and friable and of good water- holding capacity. The weed growth that comes in spontaneously on the so-called rested fields is also generally of a kind suited to turn under as a source of vegetable matter for tobacco soils. Supplying the necessary humus in this way perhaps may be con- sidered satisfactory from the standpoint of the tobacco itself. In several other respects, however, it is very unsatisfactory. The rested field system of farming, if it may be called a system, means that a 6 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. part of the farm is at all times out of commission and not producing uny profitable crop. It also means that many undesirable weeds and bushes are given every opportunity to reseed or reestablish them- selves, and it gives the country the general aspect of being roughly and poorly farmed. As such it represents an antiquated, crude, and unsatisfactory type of farming from which we are now trying hard to get away. In the New Belt section the growing of tobacco on freshly cleared land is unsatisfactory for the reason already mentioned, while in the Old Belt the proportion ef the tobacco crop grown on fresh land is already small, and it is evident that it must in the future constitute a smaller and smaller proportion of the area planted to tobacco. On old land there is no more important problem in the production of fine, bright tobacco than how best to maintain in the soil a sufficient supply of the right kind of decaying vegetable matter, upon which its life and mellowness so largely depend. Among the more satisfactory sources of vegetable matter for to- bacco soils of the flue-cured district we may note the rye (or other small grain) fallow and the herd’s-grass sod. Rye is in every respect satisfactory from the standpoint of its effect on the quality of the tobacco. It is thought well of by tobacco growers generally through- out the entire flue-cured district, but it is open to one very serious objection for general use as a crop to immediately precede tobacco. Its use necessitates the spring plowing of the land at a time when the teams are always rushed, and very frequently the land will be either too wet or too dry, or some other cause will too often prevent the proper fitting of the land early enough, or well enough, for the best results. When rye is used and turned under entire, it should not be allowed to get too tall and hard. It is best to turn it down when it is about knee high, and before being turned under it should be thor- oughly cut into the soil by going over the field two or three times with the disk harrow, lapping halfway each time so as not to throw the field into ridges. The thicker and ranker the growth of rye, the more imperative it is that a thorough job be done with the disk before the land is plowed. If the rye is cut and removed from the field, the stubble should likewise generally be thoroughly cut to pieces with the disk before plowing the land. GRASS IN THE TOBACCO ROTATION. All things considered, there is probably no better humus crop for the tobacco rotation than herd’s-grass or redtop, at least on practi- cally all the tobacco soils of the Old Belt section and the stiffer soils in the New Belt. Aside from its value as a humus-yielding, soil- improving crop, suited to the tobacco rotation, redtop is a very valuable hay grass. It is suited to southern conditions and will give THE CULTURE OF FLUE-CURED TOBACCO. a a good yield of splendid hay, which may be utilized as a secondary source of money income on the tobacco farm, either through direct sale or indirectly through live-stock products. For the best results with herd’s-grass, the seed should be sowed from the middle to the last of August in the Old Belt and not later than September 20 in the New Belt Coastal Plain section. The prepa- ration of the seed bed is a matter of prime importance in securing a good stand of grass. This is best accomplished without the turning plow, unless it be used some weeks or months before the grass is to be seeded. Instead, the field should be gone over with the disk har- row in July or August, followed by the smoothing or drag harrow just before sowing the seed. What is needed is a fine but shallow seed bed (preferably not more than 1 or 2 inches deep) with a firm under soil, and this condition can best be secured if the turning plow is not used. The place of the grass in the rotation, particularly in the Old Belt section, generally will be after wheat or oats, one of which has, in turn, probably succeeded the tobacco; that is, the grass will be seeded on wheat or oat stubble after the soil has been fitted during July and August, as mentioned. The disk should be started at the first opportunity after the grain is removed, so as to prevent the weeds from getting so large as to interfere with a satisfactory and economical fitting with the disk harrow. Before seeding the grass, from 400 to 800 pounds of 3-8-3 ferti- lizer* or its equivalent should be broadcasted per acre. On the stiffer soils, if already in a fairly good state of fertility, the smaller quantity might suffice, but on the sandier soils, especially if run down in fertility, the larger quantity would be likely to give more satisfactory results. To insure an even stand of grass, the field should be gone over both ways in sowing, using a total of about 15 pounds of seed to the acre. After seeding, the field should be again gone over with the smoothing harrow, to lightly cover the seed, and then thoroughly rolled. Early in the spring, when the young grass begins to start, top-dress the field with about 200 pounds of nitrate _of soda per acre, distributed in two applications about two weeks apart. The nitrate is best applied just before or during a rain, so that it will be dissolved, soak into the ground, and begin to feed the grass at once without any danger of injury by burning. After the lumps are crushed, the nitrate can be easily distributed directly by hand without increasing the bulk by mixing with sand or other filler. When making the second application of the nitrate, special attention should be given to any spots which, from the appearance of the grass, seem to have been missed in going over the field the first time. From this procedure a valuable hay crop of 14 to 2 tons or more 1The formula “ 3-S—3” refers to the percentage of ammonia, phosphoric acid, and potash, respectively. 8 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. per acre should result. Figure 1 shows the effect of nitrate of soda on grass grown in a tobacco rotation. The grass generally- should be allowed to stand two years, when the sod may be turned down in the fall or winter in preparation for tobacco the next year. This fall plowing is a very important point, especially in the Old Belt, as it practically assures that the soil will be well fitted and early enough fitted to give the tobacco the best chance to do well. OTHER CROPS OF THE ROTATION. It is impracticable to attempt to lay out any definite rotation plan adapted to the needs of all tobacco farms. For the Old Belt section, however, where there is less diversity in so-called money crops, a rotation in which tobacco is followed directly by oats or wheat and Fic. 1.—A field of grass showing the effect of nitrate of soda. On the right the grass was hardly worth cutting, while on the left, where nitrate of soda was used, a yield of nearly 2 tons to the acre was obtained. then by two years of grass, as suggested above, would undoubtedly be found practicable and suited to the majority of tobacco farms. A number of possible variations from this plan will quickly suggest themselves. For example, if this system of cropping, supplemented perhaps by liberal fertilizing or manuring, tends to make the soil too rich for the best results with tobacco, the difficulty could prob- ably be overcome by introducing corn into the rotation directly on the grass sod in place of the tobacco. A good crop of corn should result, and it would do much in the way of reducing the surplus fertility, for corn is an exhaustive crop, particularly on light land. This would lengthen the rotation to five years and bring the tobacco directly after corn. There is one serious objection to this plan. Corn frequently harbors large numbers of wireworms, which might THE CULTURE OF FLUE-CURED TOBACCO. 9 make it difficult to get a stand of tobacco because of the attacks of the wireworms on the young plants as soon-as they are set out. This difficulty in turn could be successfully overcome by following the corn with oats, making a six-year rotation, the field coming back to tobacco again in the seventh year. Another variation would be to follow the tobacco with corn and then with oats or wheat, to be followed in turn by the two years of grass, making a five-year rota- tion and putting the tobacco on the grass sod, as in the four-year rotation first mentioned. In the New Belt there is a greater diversity of money crops. Cot- ton, peanuts, and-sweet potatoes may be mentioned, and among these cotton would be the one most generally desired because of its ready market and wide adaptability throughout the New Belt sec- tion. Legumes are also much less objectionable on the light Coastal Plain soils, and in many instances 2 legume could be introduced into the rotation with benefit. In most cases cowpeas probably would be found most satisfactory for this purpose, or, on the stiffer soils where it will hold through the winter, crimson clover also might often be used to advantage. When used, these leeumes should gener- ally come in the rotation closely succeeding tobacco, so that any excess of ammonia which they might supply could be used up to some extent by the crops intervening before the field comes to to- baeco again. On some of the very lightest unimproved soils, tobacco might give good results even if directly following a turned-under leguminous crop, such as cowpeas. On the stiffer soils of the New Belt, the four-year rotation sug- gested for the Old Belt, namely, tobacco followed by winter oats and then two years in herd’s-grass, would be practicable in some cases. Tf it is desired to put cotton in the rotation, satisfactory results should be obtained by seeding the field to cowpeas as soon as the oats are removed. The peas should be fertilized liberally with phosphoric acid and potash (say, 200 to 400 pounds of 16 per cent acid phosphate and 100 pounds of sulphate of potash), and the peas could either be mowed for hay or turned under, generally the latter when it is de- sired to improve the soil, as the condition of the field or the need for the hay makes most desirable. The cotton could follow the peas, after which the field could be planted in tobacco again, making a three- year rotation. If the pea vines were turned under, this system ought to keep the soil well supplied with vegetable matter, and good crops of both cotton and tobacco should result with the addition of but com- paratively small amounts of nitrogen in the fertilizer. The oat crop should be top-dressed early in the spring with about 200 pounds of nitrate of soda per acre, in the manner recommended for grass. Peanuts or sweet potatoes could be introduced into the rotation if desired, either in place of or succeeding the cotton. Peanuts are 6907 °—Bull. 16—13 2 10 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. a leguminous crop, but since both the vines and the roots are re- moved in harvesting (unless used for grazing hogs) they may be considered an exhaustive rather than an improving crop. Sweet potatoes, however, leave practically everything on the field except the potatoes themselves, which are principally starch, and this crop, therefore, tends to improve the soil. The vines decay very rapidly and their plant-food content, although rather small, soon becomes again available. Here again the rotations mentioned are to be con- sidered only as suggestive, and any number of variations will readily suggest themselves to the thoughtful farmer; but the importance of maintaining a bountiful supply of vegetable matter of a kind not too rich in nitrogen at the time the field comes in tobacco should always be kept clearly in mind when planning the rotation. FERTILIZERS FOR FLUE-CURED TOBACCO. Bright-tobacco soils as a class are naturally rather infertile; but they are light and friable and of a character to respond readily to fertilizers, particularly in producing a crop of high money value like tobacco. Fertilizers increase the chances of profit from growing bright tobacco in two ways. They greatly increase the yield, some- times by 100 per cent or more, and if properly balanced they generally improve the quality. Because of the natural deficiencies of bright- tobacco soils and because of the special adaptability of commercial fertilizers te bright tobacco there are no other types of tobacco pro- duced in this country on which fertilizers are so freely used, except on some of the high-priced cigar-wrapper types in New England and Florida. A so-called complete fertilizer—that is, one containing each of the three materials, ammonia (nitrogen), phosphoric acid, and potash—is generally needed, and the maximum yield can not be secured unless ach is supplied in sufficient quantity. No general rule as to the proper proportion or balance between these materials can be given, and the farmer must exercise judgment in the matter. The best proportion for the three elements is likely to vary considerably on different fields, according to the soil and its state of improve- ment. As stated, each of these elements has its effect in limiting the yield; but, aside from this, there is, broadly speaking, a special effect on the quality of the leaf that may be attributed to each element. Too much ammonia, especially if unsupported by a suffi- ciency of the other fertilizing compounds, particularly phosphoric acid, will make the tobacco coarse, dark, and late in maturing, with a tendency to damage by “red fire” or dead spots here and there on the leaves. Without a sufficient supply of ammonia, however, the tobacco will be small, thin, and poor, although the color may be good. THE CULTURE OF FLUE-CURED TOBACCO. 11 Potash, like ammonia, improves the body of the leaf, and it has a decided value in tending to diminish or prevent “ diseasing ” or “specking.” On the light, sandy soils of the New Belt section especially, potash should be applied much more liberally than is now the general custom. Phosphoric acid may be considered the most generally needed plant-food material throughout the tobacco-growing region under consideration. It not only increases growth but hastens maturity, and also strongly tends to brighten the color because of its decided effect in ripening the leaf. By reason of this specific effect in thus improving the quality phosphoric acid should be used liberally in the tobacco fertilizer, particularly on the better improved soils, which, from an accumulation of nitrogenous materials, might tend to produce a dark, coarse leaf. On the other hand, some caution should be exercised not to use it excessively on unimproved very light soils. On such soils there is natural danger from premature ripening, or “ firing,” as it is usually called, and such tendency would be increased by an excessive application of phosphoric acid, though increasing the ammonia supplied in the fertilizer or otherwise would tend to overcome this difficulty with probable increased growth as well. This largely explains why the turning under of a leguminous crop immediately preceding tobacco on such unimproved very sandy soils may sometimes result in positive benefit. Generally speaking, phosphates (except as just indicated) and potash may be used freely on flue-cured tobacco without injury to the quality, but it requires nice adjustment of the ammonia supply to give the best results. As stated, too little will make a “ poor,” thin tobacco of small growth, while too much will tend to make the tobacco dark, coarse, and rank smelling. Ammonia in the soil comes almost entirely from decaying vegetable matter or manure, and the quantity of ammonia to be used in the fertilizer will depend largely on how much may be expected from these sources in the soil. A crop of 1,000 pounds of tobacco to the acre, to produce the leaf, stall, and roots, will need to assimilate about 75 pounds of ammonia (equiva- lent to approximately 62 pounds of nitrogen). On poorly improved sandy soils, generally producing around 600 pounds of tobacco to the acre under ordinary fertilization (say, 500 pounds of 8-8-3 fer- tilizer to the acre), the yield and quality generally could be improved greatly and the crop made more profitable by using an increased amount of ammonia in the fertilizer. On such a soil, out of the 75 pounds of ammonia necessary to produce a 1,000-pound crop it would not be unreasonable to supply in the fertilizer 40 or 50 pounds of this material (equivalent to 250 or 300 pounds of 16 per cent dried blood). 12 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE, Both phosphoric acid and potash are generally needed on practi- cally all the tobacco soils of the fiue-cured district, although potash is perhaps of somewhat less importance on the stronger soils of the Old Belt section. Neither of these materials is likely to do harm, and any unused portion will not be lost by leaching (except possibly on some of the very deep loose sands of the Coastal Plain section) but will remain to benefit succeeding crops of the rotation. It would undoubtedly be wise, therefore, to use these materials somewhat more freely than has been customary. In the New Belt this recommenda- tion would apply more particularly to potash, because the soils there are relatively more deficient in that constituent, while in the Old Belt, particularly on the more clayey soils, phosphates are more urgently needed, although a considerable increase in the potash used, particularly on the lighter soils, would also be desirable. For general use it would seem reasonable to recommend as a base the use of from 400 to 600 pounds of 16 per cent acid phosphate per acre and in the Old Belt about 100 pounds of sulphate of potash (analyzing 48 to 50 per cent actual potash, K,O) or for the lighter soils of the New Belt 150 to 200 pounds of the sulphate of potash per acre. The amount of ammonia to be used with these quantities of phos- phoric acid and potash, as indicated above, would depend largely on the condition of the particular field under consideration. In gen- eral, it may be stated that proportionately more ammonia can be used profitably on the light sandy soils of the New Belt than on the stronger Old Belt soils. Another factor of importance, particularly in the western part of the Old Belt section, is the time of harvesting and curing. If the crop ripens and is cured in warm weather, say, up to September 10, the tobacco will naturally tend to yellow well and cure bright, as compared with the same tobacco harvested and cured in the cool weather of late September and October. The normal period for curing tobacco in the New Belt is during July and early in August, which are hot-weather months, and this is a factor dis- tinctly favorable to a good bright cure. Tobacco that ripens and cures during hot weather, particularly if the soil be rather dry, can satisfactorily utilize a larger amount of ammonia than when the harvest is in cool weather, and wet weather just before the tobacco is harvested is an additional adverse factor. Increasing the. phos- phoric acid, as noted above, will tend to brighten the leaf and thus overcome some of the harmful effects of too much ammonia. In the Old Belt section under average conditions, particularly on the stronger type of soils of the western part. probably about 150 pounds of 16 per cent dried blood (or its equivalent in some other good ammoniate) would give approximately the right proportion of = THE CULTURE OF FLUE-CURED TOBACCO. 133 ammonia for the minimum amounts of phosphoric acid and potash mentioned above. The formula would be as follows: Pounds. Dried blood, analyzing 16 per cent ammonia________________ 150 Acid phosphate, analyzing 16 per cent phosphoric acid_______ 400 Sulphate of potash, analyzing 50 per cent potash (IK.0)__.____ 100 Totale— GO Such a mixture, while weighing only 650 pounds for an acre of land, would, in the quantities of plant food carried, be approxi- mately equivalent to an 800-pound application per acre of a fertilizer analyzing 3 per cent ammonia, 8 per cent phosphoric acid, and 6 per cent potash. If desired, cottonseed meal (analyzing 74 per cent ammonia) might be substituted for the blood, using twice the number cf pounds; or nitrate of soda (analyzing 18 to 19 per cent ammonia). at the rate of about two-thirds the number of pounds of blood, could be used. Generally speaking, however, cottonseed mea! is somewhat less active than blood on the basis of equivalent quantities of am- monia, while there may be some question whether nitrate of soda does not affect unfavorably the quality of the leaf produced. The cost of the 650 pounds of fertilizer shown in the formula will. vary somewhat from year to year, but will generally be about $10. In certain cases, of course, as when the soil had been consider- ably improved by the use of manure or leguminous crops, even a smaller quantity of ammonia than here mentioned might give better results. In extreme cases, especially when color is an important factor, the ammonia might be omitted altogether. On the other hand, in the case of the hghter types of soil in the Old Belt, particu- larly in the eastern part of that section, where the lighter types of soil predominate, the proportion of ammonia in the fertilizer gen- erally could be somewhat larger than that shown in the above formula. For these conditions 200 pounds of blood, or even more in some cases, might be a better balance and prove more profitable. In the New Belt section, with the combination of still lighter and weaker soils and early harvesting in warmer weather, a materially richer fertilizer could undoubtedly be used to advantage in most ‘cases, and for that section a mixture may be recommended for average conditions composed about as follows: Pounds. Dried blood, analyzing 16 per cent ammonia_______________ 250 Acid phosphate, analyzing 16 per cent phosphoric acid________ 500 Sulphate of potash, analyzing 50 per cent potash (K.O0)_____ 150 Reta 5-8 eae Pa oe Safar Mh Foe as SST) Pe 900 This mixture of 900 pounds for an acre of land would be equiva- lent in plant-food value to a 1,000 pound per acre application of a 14 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. fertilizer analyzing 8 per cent of phosphoric acid, 4 per cent of ammonia, and 74 per cent of potash. On the very lightest soils of the New Belt section, for reasons already mentioned, better results might be obtained by reducing the phosphoric acid, say, to 400 pounds, or by increasing the blood (ammonia) to 300 pounds or more, thus narrowing the ratio between the ammonia and phosphoric acid to 5 or 54 to 8 instead of 4 to 8 as shown in the formula as given. Fertilizers for tobacco are generally applied in the row, and when used in the ordinary quantities better immediate effects are no doubt realized. When considerable fertilizer is used in the row, however, even in the quantities mentioned above, it shouid be thoroughly in- corporated with the soil by running a double-shovel plow with nar- row teeth along the row before it is bedded. When large quantities of fertilizer are used, it might be best to apply at least half broadeast. In connection with the use of fertilizers, it is assumed that the humus supply has been given due consideration, thus insuring a good physical condition and moisture-holding capacity. A tight, drought- stricken, or badly drained soil can not be expected to become very productive just by increasing the supply of plant food in the form of commercial fertilizers. In the above discussion no special mention has been made of the relative value of the different sources from which the plant-food materials may be derived, and this has purposely been omitted for the sake of brevity. It should be stated, however, that the materials mentioned may be regarded as standard, in the ight of our present knowledge, and as good as anything now on the market. As a source of potash, however, the sulphate should generally be given the preference in a tobacco fertilizer. The other materials most likely to be used as a substitute are muriate of potash and kainit. Both of these materials contain large quantities of chlorin, which has a tendency to make the tobacco burn poorly. Complaints have frequently been made as to the poor burning quality of flue- cured tobacco, particularly in respect to tobacco from the New Belt section, and it would be unwise to use anything in the fertilizer which would tend to strengthen the basis for this criticism. BARN MANURE FOR FLUE-CURED TOBACCO. While commercial fertilizers are and of necessity must remain the chief reliance of the tobacco grower, barn lot or stable manure is used to some extent on bright tobacco, although it has opponents as well as advocates of its suitability for this crop. In so far as its use may be considered objectionable, the objection has the same basis as that of other organic materials overrich in ammonia, namely, the tendency to make the tobacco coarser and darker. The lighter and poorer the land in respect to other ammoniates, the more likely is the THE CULTURE OF FLUE-CURED TOBACCO. 15 manure to be found desirable and advantageous. The way in which the manure is used is also an important factor in determining its effect on the quality of the crop. If well rotted and applied some months before the tobacco is planted, it can generally be used in mod- erate quantities with decided benefit, except, as already indicated, on lands already abnormally rich in ammonia. Where possible, it should be applied the fall before planting the tobacco, and certainly not later than the first of March. When used at the rate of 2 or 3 tons to the acre it can be applied in the row. When used in larger quantities (5 or 6 tons per acre is about as heavy as it is generally advisable to use manure for bright tobacco as a direct application), it should be broadcasted over the land and either harrowed or plowed in. Only fine, well-rotted manure should be used in the row, and it should be applied as much as two months before planting if pos- sible. In using manure in this way the rows may be laid off in February or early in March and the manure put out and covered with the turning plow. Just before planting time these rows may be reopened with a single-shovel plow, the additional fertilizer applied, and the land rebedded in preparation for setting the tobacco. Where tobacco succeeds herd’s-grass in the rotation, an excellent method is to apply the manure to the grass during the winter before the last season the field is to stand in grass. This would greatly help the hay crop and give the manure time to become thoroughly decom- posed and incorporated with the soil. THE USE OF LIME ON FLUE-CURED TOBACCO SOILS. Most flue-cured tobacco soils contain sufficient lime to fill direct plant-food requirements, but not enough generally to keep them from becoming rather acid. Their general crop-producing power through enhanced bacterial efficiency would usually be improved if they were occasionally limed. The grass especially would yield much better if lime were occasionally used. The direct effect of lime on the tobacco, however, may be somewhat injurious to the quality. By hastening the decay of the vegetable matter in the soil it increases the ammonia supply, and on soils already tending to be overrich the lime will tend still further to make the tobacco dark and coarse, the same as if an increased supply of ammonia were rendered available in any other way. On some very poor soils, however, lime might result in both a larger yield and better quality because of the increased food supply rendered available. It is somewhat a matter of controversy, also, whether lime does not tend to injure the burning quality of tobacco. When lime is used in the tobacco rotation it seems wisest, therefore, to use it imme- diately after the tobacco comes off and before the wheat or oats are 16 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. seeded. It would thus tend to help the immediately succeeding crops, particularly the grass, and would be largely out of the way, so far as its direct effect is concerned, by the time the field is again planted to tobacco. On tobacco lots, lime should not be used ordinarily oftener than once in about four years and at a rate not to exceed one- ’ half ton of quicklime or its equivalent per acre. VARIETIES OF FLUE-CURED TOBACCO. A great array of so-called tobacco varieties might be listed, but many of them would represent but little, if any, real variation in type. There is, however, one broad differentiation among the many so-called varieties, based on shape and size of leaf, which can be readily observed. Thus we have the broadleaf types, represented by such standard sorts as Warne, Yellow Oronoco, White-Stem Oronoco, Big Oronoco, Adcock, Adkin, Willow-Leaf, Gooch, Tilley, and Hester, and the narrow-leaf sorts, as Narrow-Leaf (little) Oro- noco and Flanagan. Throughout the New Belt and on the lighter soils of the Old Belt section the broadleaf types are generally preferred, as they are better adapted to the production of smokers, cutters, and wrappers. On the stronger soils of the western part of the Old Belt section, particularly westward from Rockingham County, N. C., and Henry County, Va., the narrow-leaf sorts are general favorites. These nar- row-leaf varieties will make good, rich filler on suitable land, and by somewhat closer planting on improved land a large yield per acre can be grown without the individual leaves becoming overgrown and coarse. Flanagan and some of its subtypes, particularly the Im- proved Flanagan, are rather large-leaf types, about midway between the narrow-leaf and the broadleaf sorts, and are well adapted to quite rich land. The variety known as Short-Stalk Flanagan closely resembles the Narrow-Leaf Oronoco. The Flanagan types are per- haps the most vigorous growers and heaviest yielders of any of the flue-cured varieties, but they are a trifle later in maturing than the others. On the fine, bright soils the broader leaf types are generally most popular. The Warne, a standard wrapper type, is perhaps the most popular of any. The White-Stem Oronoco, Willow-Leaf, and Gooch are favorites in certain parts of the New Belt section. The Adcock is a great favorite in the noted wrapper-producing section in the southern part of Granville County, N. C. The Adkin is also a popu- lar broadleaf sort in certain sections of the Old Belt and has the merit of being some days earlier in maturing than most of the other standard sorts, but this earliness is probably somewhat at the sacrifice of yield. THE CULTURE OF FLUE-CURED TOBACCO. ily The distance between the leaves on the stalks is somewhat greater on these broadleaf types than on the narrow-leaf sorts, the spacing being particularly wide in the case of the Adcock. It should: be noted, perhaps, that any of these varieties will have the leaves more closely or wider spaced according to the nature of the soil, especially in respect to moisture conditions. With an abundance of moisture the spaces between the leaves will be wider, and under droughty conditions the leaves will be crowded much more closely together. This is a general principle in respect to all vegetation. SELECTION AND CARE OF SEED PLANTS. In selecting seed plants, close atten- tion should be given to all the points that go to make up the ideal plant, accord- ing to the standard which the grower should have clearly inmind. The largest plants in the richest part of the field are not necessarily the best for seed pur- poses. IP he e€ strains of Fic. 2.—A seed head of tobacco covered with a paper bag seed can be saved eas zea with certainty only by covering the seed head during the blossom- ing period so as to prevent mixing or crossing with inferior plants or suckers by the passing of insects from flower to flower on differ- ent plants. For this purpose an ordinary light-weight but strong paper bag of about the 12-pound size, such as can be obtained at any grocery store, is most practical. A day or two before the first flowers open the bag should be tied about the head (fig. 2), which first has been trimmed to a “ crow-foot.” The bag should be loosened and raised up every few days, as the seed head grows, and the 6907°—Bull. 16—13 ‘ 3 18 BULLETIN 16, U. S. DEPARTMENT OF AGRICULTURE. flower débris shaken out. After all the flowers of the crow-foot are opened and the seed pods begin to swell, the bag may be removed if desired, but it will be necessary to keep all other flower branches and buds constantly picked off. In harvesting, only the fully matured and ripe pods should be saved. Such as are underripe should be picked off and discarded. After they have been shelled out, the hghter, imperfect seeds should be got rid of by some simple winnowing device, for the same reason ihat wheat or other seed are cleaned of inferior grains before sowing. A satisfactory separation of the seeds can be made also by settling them in a glass of water. After half or two-thirds of the seeds have sunk to the bottom, at the expiration, probably, of two or three hours, the floating seeds may be skimmed off and the heavy seeds that have settled can be dried on blotting paper. PREPARATION AND CARE OF THE SEED BED. It is the almost universal custom throughout the entire flue-cured district to prepare the seed bed on freshly cleared land, either in the woods or in some other suitable location. The reason for this is that there is an abundance of humus in such land. It is not compacted and baked by heavy rains and the sun, and the plants grow faster on fresh land than on old land. The particular spot of land chosen should be loamy and mellow and naturally moist, but having good drainage and free from standing water at all times. It is desirable usually to locate the bed near a stream of water. At such places the land is apt to be naturally moist, and in the event of an extreme drought the bed can be more readily watered artificially. An exposure to the south or east will give the earliest plants, although it is best to have at least two beds, one a little later than the other. The spot chosen should also be as free from weeds or grass as possible, and generally, as further insurance against a weedy bed and to kill soil insects as well, the bed should be burned during the winter before it is seeded. If plenty of good dry brush is avail- able (pine brush is best) the bed can be most easily and cheapiy burned with this material. Usually it is necessary to haul the brush at least a short distance. This can best be done by piling it compactly ona 12-foot wagon frame. About eight good loads of well-compacted brush will usually be required for a bed of 100 square yards. Before the brush is piled on the bed, the leaves or other litter should be raked from it, as they hold moisture and would tend to prevent the heat from penetrating the soil to a sufficient depth. If brush in sufficient quantity is not available or it is desired to burn the land very thoroughly, a combination of wood and brush may be used. Burning in this way will require about 3 cords of wood for 100 square THE CULTURE OF FLUE-CURED TOBACCO. 19 yards. Long poles or skids are laid along the ground at intervals of about 4 feet. Across the ends of these skids on the upper side of the bed, brush and wood is piled about 4 feet wide and 3 feet high. This pile is set on fire in several places. With considerable attention it will generally burn down sufficiently in about a half hour. The embers are then pulled down with hoes or hooks with long handles to the adjacent strip 4 or 5 feet wide just below. The fires are renewed by piling on more wood and brush and allowed to burn down for another half hour, or until the soil beneath seems well heated and dried out to a depth of about 3 inches. This process is repeated until the whole bed is gone over. A spell of dry weather when the ground is free from frost should be chosen for burning. If the soil is wet, it will take much more heat to burn with the same efliciency because of the increased amount of water to be evaporated, and in some cases the physical condition of the soil might be injured by burning when the soil is too wet. The bed may be burned at any suitable time during January or February, or even as late as the middle of March in the western part of the Old Belt section. The burning of the soil puts it into good tilth, and generally it can be worked up and sowed to best advantage at that time.