FLUE-CURED TOBACCO Chemical Composition of Flue-Cured Tobaccos Produced on Limed and Nonlimed Soils under Varying Weather Conditions' F. R. DARKIS, L. F. DIXON,2 F. A. WOLF, AND P. M. GROSS Duke University, Durham, N. C.
Chemical analyses of flue-cured tobaccos produced on limed and nonlimed soils are presented. The tobaccos were grown under various fertilizations for six consecutive growing seasons, during which rainfall conditions were widely divergent. The changes in chemical composition brought about by the use of dolomitic limestone are pointed out. Certain postulations are offered to explain the manner in which the limestone operates to effect these changes. The changes in composition induced by liming are detrimental to the quality of flue-cured tobaccos. Evidence is given to show that adverse weather conditions or a lack of rainfall may accentuate the ill effects of dolomitic limestone.
he usually harvested part of the tobacco in an immature condition. Such tobacco cured poorly and was of inferior quality. The continued application of lime to the soil thus resulted in increased yields of poor-quality tobacco and a decreased return to the grower. I n an attempt t o determine the cause of this anomalous situation, a comparative study of the chemical composition of tobaccos produced on limed and nonlimed soils was initiated by this laboratory in 1928. This chemical study is based upon analyses of tobacco crops produced on the same series of plats over a 6-year period, thus taking into account the effect of varying weather conditions (8,9).This paper presents a part of this study in condensed form and also an interpretation of the data which seems to explain the detrimental effects of liming.
Materials and Fertilization
D
URING the period 1920 to 1930 many growers of flue-
cured tobacco in Virginia, North Carolina, South Carolina, and Georgia began the use of lime on fields cropped with tobacco. This gave promise of being a desirable procedure a t first because the volume of the crop was thereby generally increased and the color of the cured leaf was improved. The proportion of the crop produced on limed soils that cured out with a bright yellow color, moreover, was usually increased. The increased yields and the better price secured because of this bright yellow color increased the return to the producer. Meanwhile, buyers of tobacco had found by experience that these bright yellow tobaccos produced on limed soils tended to age more slowly than tobaccos from nonlimed soils. As the farmer continued the practice of liming the same fields, he found that the succeeding crops did not mature3well, and that The first three papers of this series appeared in INDUBTRIAL A N D ENQICBEMIETRY in Octobkr, 1935, page 1152, February, 1936, page 180, and October, 1936, page 1214. A fourth, dealing with anatomical features of flue-cured tobacco appeared in the Bulletin of the Torreg Botanzcal Club, 64, 117 (1937). * Present address, Champagne Paper Corporation, New York, N. Y. a The leaves of tobacco plants of the flue-owed type are said to be mature when they will develop a color ranging from an orange to a bright yellow on being subjected to the flue-curing process. The experienced grower of flue-cured tobaccos possesses the ability to recognize this condition in maturing leaves and primes them at the time it is detected. A varying proportion of all crops of flue-cured tobaccos never attains complete maturity, the leaves developing colors ranging from dark green to light gray on curing 1
NEERTKQ
The tobaccos used for the analyses were of the Durham type. They were produced on the Tobacco Experimental Station, one mile southwest of Oxford, N. C. This experimental farm is conducted by the U. S. Department of Agriculture, Bureau of Plant Industry, in cooperation with the North Carolina Department of Agriculture. Adequate description and analyses of the soil of this farm and the crop rotation practices followed are available ( I d , 33, 34). The results given here were obtained from handling the entire production of the specific I/qg-acre plats of six crops grown under markedly different weather conditions. The tobaccos were produced during 1928, 1929, 1930, 1931, 1932, and 1933. The plats were subjected t o the cultural and handling methods in current practice on the Tobacco Experimental Station. The fertilizer materials were mixed a few days prior t o their application in the field. The mixtures were applied in the drill, and the quantity for each row of each plat was weighed to ensure uniformity. The fertilizer was distributed by hand in an open furrow, and then the land was ridged over the fertilizer. Application was usually made a week or 10 days prior t o transplanting. Where lime was used, it was applied at the rate of 1 ton of ground dolomitic limestone (12 per cent magnesium) per acre. It was applied broadcast once every 3 years or once for each crop of tobacco. This practice was begun in 1920 and was continued through 1929. The land producing the 1929 and 1932 crops was limed in 1920, 1923, 1926, and 1929. The land producing the 1930 and 1933 crops was limed in 1921, 1924, and 1927. The land producing the 1928 and 1931 crops was limed in 1922, 1925, and 1928. The following crop rotation was used: The first year, tobacco was followed by winter oats. The second year, oats were cut for hay, and then soybeans were planted by broadcasting; after growtK, the soybeans were disked and the land was seeded t o Abruazi rye. The third year, the Abruzzi rye was cut for seed and the land left to grow weeds. The field was plowed in the fall or early winter and planted t o tobacco Many factors operate in determining the degree of maturity the leaf may attain, such as type of soil, crop rotation, fertilization, position of the leaf on the stalk, length of the growing season, and amount and distribution of rainfall.
1030
SEPTEMBER, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
1031
the next year. NO fertilizer was applied in this 3-year period except that applied for the tobacco crop. The basic fertilizer formula used on the plats, in addition to the lime, consisted of 800 pounds per acre of 4-8-6 (NPK) derived from the materials given in Table I.
ing Seasone covered by this study, except in the case of the KPK plat of the 1928 crop. I n general, the nicotine content is somewhat lower in the tobacco grown on the limed portion of the plats. This is the case for the tobaccos from each plat during the 1928, 1929, 1932, and 1933 growing seasons. The difference in nicotine content of the tobaccos TABLEI. SOURCES OB NPK IN THE FERTILIZER AND AMOUNT OF APPLICATION PER ACRE of the 1931 crop grown on the two portions of the Fertilizer Phosphoric Acid Potash as plats is not significant. During the 1930 season Treatment Nitrogen as NH3 as Pzo6 Kz0 the tobacco grown on the limed part of the NPK (muriate) and NPK (mixed nitrogen) plats was ?JP 1 / z x 40 lb. NH3 as dried blood 64 lb. P206 as acid 24 lb. KzO as phosphate significantly higher in nicotine content than that NPK (muriate), K 40 lb. NH3 as dried blood 64 lb. PzOs as acid 48 lb. Kz0 as grown on the nonlimed portion. phosphate KCl as KCl NPK (mixed ni-
5 lb. NHs as NaN08; 5
64 lb. P z O as ~ acid 45 lb. KzO as lb. NH3 as (NHI)~SOI; phosphate KzSOi 15 lb. NHa as cottonseed meal; 15 lb. NH3 as dried blood NPK (K as sulfate) 40 lb. NH3 as dried blood 64 lb. PzOs as acid 45 lb. K20 a8 phosphate KzSO4 NPK (ammo- 30 lb. NH3 as ammonium 64 lb. PZOSas acid 48 lb. KzO as mum sulfate) sulfate phosphate KzSO4 trogen)
The plants were topped when they were high enough to produce approximately eighteen leaves per plant. After topping, the sucker growth was removed at 7- to 10-day intervals until near the close of the priming season. The tobacco was harvested by the priming method. When the leaves were considered mature, they were removed from the stalk, labeled, and cured by the flue-curing process. After storing for about 15 weeks, the tobacco was graded by the farm grader, and production data by plats were obtained. The tobacco was sent to the laboratory at this time and was airdried, and large portions of each grade were ground on a Wiley mill fine enough to pass a 30-mesh sieve. The entire leaf, including ribs and lamina, was used for analysis. A composite sample of each fertilizer treatment for each year was made from the individual grades, by mixing the different grades in the proportion in which they were produced. The samples were stored at 32' t o 36Q F. until analyzed.
Methods The methods used in determining the organic constituents, soluble ash, calcium, and potassium were described in two previous papers (8,9).The following were determined by the A. 0. A. C. methods (2): silica (page 39), magnesium (page 40), oxides of iron and aluminum (pages 39 and 40), sulfur by the magnesium nitrate method (page 45), chlorine by the volumetric method (page 44),and phosphorus by the volumetric method (page 3), the extract being prepared by method 6a (page 2). All chemical data are calculated to a moisture- and sand-free basis. Table I1 represents over a thousand specific analyses of tobaccos produced during six growing seasons. Analyses were made for eighteen constituents on all samples obtained from the limed and nonlimed portions of five plats each season, each plat being fertilized differently. Attention will be focused on the over-all effects of liming as shown by the averages of the analyses. I n future publications relative to plant nutrition and the evaluation of tobaccos by means of their chemical composition, frequent reference will be made to these individual analyses.
Nitrogenous Constituents The tobaccos produced during 1928 and 1929 on the limed portion of the plats possessed a lower total and soluble nitrogen content than those produced on the nonlimed portion. During the seasons of 1930,1931,1932, and 1933, tobaccosfrom the limed portion of the plats were higher in total and soluble nitrogen content than those from the unlimed portion. The a-amino nitrogen content is higher in those tobaccos from the limed portion of each plat during each of the six grow-
Carbohydrates and Acids
The percentage increases or decreases menparagraphs are the perin the centage changes in the chemical constituents. of the nonlimed tobaccos US. the limed tobaccos, the amounts in the nonlimed tobaccos being used as the standard. The reducing and total sugar content was found to be lower in that tobacco produced on the limed portion of the plats, with the single exception of the NPK (mixed nitrogen) plat in the 1930 crop. The average decrease for the six crops was over 21 per cent, and was considerably greater in the 1931, 1932, and 1933 crops than in the 1928, 1929, and 1930 crops. Theweather conditions duringthe 1931,1932,and 1933 growing seasons were such as to delay ripening and prevent maturity. This circumstance accounts, in part, for the larger decrease in sugar content, the weather accentuating the influence of lime in delaying maturity. A low sugar content is associated with immature tobacco of poor quality (9). The tobacco from the plat receiving the NPK (muriate) formula is the highest in sugar. This is probably due to the effect of chlorine. Garner (13) found that the use of chlorine tended to cause the sugar content of tobacco to increase. The total acid content is much higher in tobaccos produced on the limed part of the plats, the average increase being about 48 per cent. The increase in tobaccos produced during 1928, 1929, and 1930 is greater than those produced during 1931, 1932, and 1933. The increase in acids is greatest in those crops where the decrease in sugar is least. Unpublished work by this laboratory indicates that the sum of the acid and sugar contents of various flue-cured tobaccos tends to approach a constant value. If the tobaccos from the limed and nonlimed portions of each plat are considered separately, these sums show a similar trend from year to year. I n the case of the present samples this sum is greater for the tobacco produced on the limed plats than for that from the nonlimed ones. The increase in acid with liming is least in that tobacco from the N P K (muriate) plat; concomitant with this, the increase in calcium is also least The calcium content, however, of the tobacco from the nonlimed and limed muriate plats is appreciably greater than that of the tobacco from the other plats to which an equal amount of potassium was applied. I n the presence of muriate, therefore, the increase in calcium in the plant, due to an increased amount of calcium in the soil, is less pronounced. Since the organic acid content of the tobacco from the nonlimed portion of this plat is approximately the same as that from the other nonlimed plats, it appears that more of the cations are held in inorganic combination when the plant contains an increased amount of chlorine. Without exception, the tobacco from the limed portion of each plat in each of the crops is more alkaline, as measured by pH, than that from the nonlimed part. This decrease in ionizable acidity is opposite to the increase in total acidity and amino acid content, both of which increase with liming. Prob-
INDUSTRIAL AND ENGINEERING CHEMISTRY
1032
VOL. 29, NO. 9
ANALYSISOF TOBACCO OF SIX TABLE11. PERCENTAGH
Crop
-NP Nolime
K--Lime
L N P K (Muriate)Nolime Lime
7
1928 1929 1930 1931 1932 1933
...
2.34 2.36 2.65 3.37 3.08
-
Av. 2.76
1928 1929 1930 1931 1932 1933
1928 1929 1930 3931 1932 1933
0 : io2
0,287 0,329 0,564 0.352 Av. 0.347
15:51 11.53 10.77 5.85 11.01 A v . 10.93
i:92 2.33 3.05 4.16 3.30 2.95
2.53 1.95 2.30 2.54 3.47 2.59 2.56
2.46 1.87 2.58 2.68 3.76 2.79 2.69
0 :269 0 357 0.489 0,840 0.521 0.495
0.314
0.419 10.96 14.43 10.32 8.29 3.99 8.27 9.38
11.47 14.34 15.77 16.28 20.99 18.01 16.14
17.95 20.45 20.65 21.97 29.72 24.84 22.60
3.86 6.73 4.81
6.57 3.96 6.41 5.32
5.04 6.34 5.36
6.00 6.71 5.83
6.11 3.86 6.71 5.22 5.83 6.51 5.71
...
3.17
32.65 30.36 26.49
4.38 6.78 5.16 5.97 6.53 A v . 5.76
...
7
1928 1929 1930 1931 1932 1933
1928 1929 1930 1931 1932 I933
...
1.67 1.58 2.09 2.22 1.70 Av. 1.85
... 4.00 3.57 2.97 4.42 4.12 Av. 3.82 c
1928 1929 1930 1931 1932 1933
2.14 2.08 2.49
3.05 2.09 3.13
2.28 2.09 2.22
2.46 2.03 2.65
3.07 2.82 2.37 3.19 2.25 2.26 2.68
2.81 3.51 4.35 3.36 5.38 4.68 4.01
3.59 4.044.39 4.05 5.14 5.16 4.40
0.25 0.21 0.17 0.18 0.25 0.31 0.23
0.33 0.20 0.17 0.17 0.21 0.30 0.23
0.49 0.35 0.43 0.40 0.43 0.53 0.44
0.41 0.34 0.37 0.34 0.39 0.40 0.38
... 4.70 4.18 3.97 4.72 4.89 4.49
... 0.17
... 0.18
... 2.12
... 2.12
2.29 2.59 3.34 2.82 2.63
2.32 3.01 3.61 3.26 2.86
0.15 0.20 0.24 0.22 Av. 0.20
0.14 0.19 0.22 0.20
8
.*.
3.04 2.20 2.15 2.58 3.26 2.82 2.68
0.323
14,'60 12.17 11.74 6.91 11.00 11.28
0.296 0.453 0.657 0.504 0.448
Or346 0.248 0.274 0.308 0.416 0.291 0.314 8.71 13.94 14.65 8.99 6.84 11.46 10.77
10:66 12.66 6.54 5.17 7.52 8.49
Lime 7
2.65 2.21 2.37 2.83 3.93 3.09 2.85
2.93 1.98 2.22 2.27 3.49 3.12 2.74
2.78 1.74 2.30 2.93 3.75 3 26 2.78
0.335 0.352 0.366 0.405 0.646 0.435 0.423
0.340 0,194 0.311 0.316 0.468 0,336 0.328,
2.83 2.12 2.26 2.61 3.39 2.89 2.67
2.63 1.97 2.38 2.90 3.84 3.14 2.82
0.324
0,329 0.300 0,355 0.444 0.711 0.473 0.443
7
0.440
8.06 12.01 11.70 6.48 4.72 8.10 8.51
7.72 16.88 12.16 8.48 6.18 8.95 10.06
6.92 14.19 11.00 5.48 5.01 8.26 8.48
10.15 15.57 13.07 10.07 6.22 10.70 11.04
8.65 13.01 11.38 6.65 4.61 7.93 8.71
0.19
...
l3:32 15.22 15.02 19.61 18.02 16.22
...
4.30 6.70
5.31 6.10 6.64 5.81
...
2.93 3.02 3.15 2.49 2.55 2.83
2.83 3.09 2.67 3.51 3.36 3.09
...
22163 22.64 23.59 28.92 27.71 25.10
18.07 17.05 15.96 17.06 20.26 19.06 17.91
23.87 24.11 24.76 23.12 31.57 27.89 25.89
14.67 12.61 16.94 15.27 19.38 19.12 16.33
24.94 24.70 23.52 24.14 29.73 27.23 25.71
14.74 14.77 15.09 15.82 20.74
22.25 23.06 22.99 23.08 30.52
19.06 16.95
27.54 25.10
5.61 4.18 6.25 5.44 5.74 6.84 5.68
6.15 4.17 6.97 5.71 5.96 6.97 5.99
5.79 4.13 6.64 5.61 5.88 6.70 5.79
6.21 4.23 6.64 5.43 6.04 6.80 5.87
5.92 3.96 6.55 5.28 5.61 6.53 5 61
3.23 2.91 2.36 3.50 2.58 2.51 2.85
3.13 2.70 2.48 3.22 2.84 2.68 2.84
3.10 2.80 2.27 3.30 2.80 2.68 2.83
3.20 2.68 2.26 3.02 2.49 2.30 2.63
3.13 2.77 2.40 3.16 2.47 2.43 2.70
3.40 4.40 4.31 3.79 4.62 4.47 4.17
2.47 3.03 3.70 2.70 3.56 3.69 3.19
3.72 3.98 4.48 3.94 4.34 4.46 4.15
2.69 3.41 3.61 2.92 4.21 3.86 3.50
3.57 4.23 4.27 3.86 4.64 4.64 4.25
0.28 0.20 0.17 0.20 0.22 0.21 0.21
0.27 0.24 0.18 0.22 0.25 0.29 0.24
0.25 0.23 0.17 0.19 0.24 0.29 0.23
0.26 0.20 0.18 0.20 0.24 0.25 0.22
0.29 0.21 0.16 0.19 0.23 0.24 0.22
0.66 0.37 0.52 0.40 0.42 0.53 0.48
1.16 0.46 0.87 0.63 0.88 0.87 0.81
0.69 0.39 0.76 0.48 0.43 0.60 0.56
0.84 0.43 0.69
0.69 0.38 0.54
0.54 0.63 0.69 0.62
0.40 0.40 0.51 0.46
Petroleum Ether Extract
...
3.79 6.41 5.30 5.58 6.27 5.47
5.90 4.35 6.34 5.65 6.17 7.16 5.83
Potassium (KaO)
... 3.16
3.31 3.05 2.11 3.51 2.46 2.56 2.84
2.91 3.34 2.42 2.59 2.89
Calcium (CaO) . ,
...
2.78 3.68 3.36 2.88 4.17 3.47 3.39
4.01 4.01 3.54 4.36 4.24 4.03
Oxides of Iron and Aluminum (Fer03 f AlzOa)
,---
1928 1929 1930 1931 1932 1933
-AvQrEge--
No lime
T o t a l Aciditya
23.45 21.10
...
N P K (AmmoniumSulfate) Lime
No lime
Total Nitrogen
0: i28
14.02 16.93 14.87 10.36 5.32 11.49 12.17
13:ie 11.21 6.45 4.16 7.51 8.66
2i:iO 23.37 22.58
7
1928 1929 1930 1931 1932 1933
-*/4
a-Amino Nitrogen
16:k4 14.55 15.49 4 v . 18.23
NPKNolime Lime
(Miwed,N)Nolime Lime
,---
1928 1929 1930 1931 1932 1933
--
-NPK
0.39 0.42 0.54 0.67 0.52 0.40 0.58 0.38 0.62 0.48 0.44 4 v . 0.56 Co. of 0.1N alkali pel pram of dry tobacco.
0:is
0.18 0.22 0.25 0.22 0.21
...
0.45 0.83 0.51 0.62 0.77 0.64
...
0.26
0.24 0.15 0.21 0.26 0.20 0.21
0.21 0.20 0.19 0.22 0.22 0.22
7
'
Total Sulfur ( 8 )
0:i1 0.53 0.40 0.38 0.53 0.45
ably the ionizable acidity content is due in part t o the presence of small amounts of mineral acids and the inorganic salts of these acids. The sulfur and chlorine content of the tobacco oroduced on the nonlimed Part is the higher. Sulfur and Lhlorine are present, principhly in the form of inorganic anions. It is probable that a part of the increase in ionizable acidity in the tobacco from the nonlimed plats can be traced to this source. The material soluble in petroleum ether is somewhat lower
0.85 0.46 0.63 0.63 0.63
0.67 0.65
-
-
(4.4per cent) in the tobacco from the limed portions, with the exception of the plat receiving the NPK (muriate) formula in the 1930 crop. This is the plat that showed the reversal in the case of nicotine content.
Ash Constituents The tobacco produced on the limed portion of each plat was greater in soluble ash content (9, page 1215), with the exception of four of the plats of the 1932 crop. The increase aver-
SEPTEMBER, 1937 CROPSGROWN
INDUSTRIAL AND ENGINEERING CHEMISTRY
WITH AND WITHOUT
DOLOMITIC LIME -a/4
-NP ’/z Nolime
KLime
IO33
-NPK
(Muriate)Nolime Lime
-NPK (Mixed N)-NPK----. Nolime Lime N o lime Water-Soluble Nitroeen ... 1.90 1.31 1.39 1.28 1.58 1.60 1.50 1.51 1.76 1.56 2.21 2.45 2.29 2.02 2.04 1.72 1.72 1.83 1.73
Lime
N P K (AmmoniumSulfate) No lime Lime
Crop Bv.No lime Lime
7-
-
I
1:39 1.73 1.54 2.32 1.96 1.79
i:ig 1.61 1.84 2.77 2.19 1.92
1.52 1.20 1.43 1.56 2.40 1.75 1.64
1.48 1.19 1.63 1.60 2.50 1.93 1.72
t . .
1.59 1.39 1.64 1.65 2.63 1.95 1.81
1.84 1.27 1.55 1.58 2.40 1.94 1.76
1.72 1.11 1.62 1.72 2.61 2.02 1 80
1.75 1.31 1.56 1.55 2.32 1.88 1.73
1.60 1.24 1.62 1.71 2.59 2.03 1 81
...
...
2.85 4.27 3.21 4.74 4.15 3.84
2.30 3.99 3.24 3.75 3.76 3.41
3.64 2.31 3.37 3.02 4.77 3.93 3.51
3.50 2.01 3.93 2.98 4.14 3.86 3.40
2.65 3.82 3.08 4.50 4.29 3.67
2.22 3.98 3.19 3.77 4.26 3.48
4.35 2.59 3.08 3.03 4.76 3.95 3.63
3.63 2.46 3.09 2.88 4.12 3.91 3.35
4.23 2.38 3.56 3.04 4.58 4.24 3.67
3.72 1.87 3.57 3 0 88 4 .. 1 4.02 3.41
4.07 2.56 3.62 3 .08 4.67 4.11 3 66
3.62 2.17 3.71 33.90 .07 3.96 3.41
14: 27 11.72 6.70 4 68 7 72 9.02
14.81 17.58 16.43 10.94 5.55 11.90 12.70
11.02 14.71 10.77 8.58 4.27 8.46 9.64
14:ao 12.94 12.13 7.18 11.24 11.62
l6:56 13.21 6.86 5.50 7.79 8.78
9.66 14.63 15.43 9.27 7.03 11.77 11.30
8.44 12.25 12.12 6.68 4.98 8.42 8.82
8.46 17.38 12.58 9.00 6 .51
7.31 11 4 .. 2 58 3 1 5 . 7 8 5.32
10.98 16.05 13.73 10.51 6.49
8.92 13.26 11.82 6.92 4.95
9.30 10.54
8.54 8.79
11.08 11.50
8.19 9.02
4.78 5.28 5.31 4.98 4.98 5.22 5.05
5.11 5.34 5.67 5.24 5.13 5.49 5.29
4.91 5.25 5.02 4.98 4.91 5.23 5.03
5.21 5.32 5.22 5.35 5.31 5.44 5.30
4.94 5.19 5.12 5.02 4.99 5.19 5.07
5.18 5 .. 33 63 5 5.37 5.33 5.42 5.34
12.07 11.86 11.46 11.76 13.84 12.64 12.27
12.37 13.31 12.36 11.84 13.09 13.30 12.71
12.94 11.82 11.51 11.61 12.45 11.86 12 03
13.23 12.16 11.52 12.17 11.56 12.03 12.12
12.67 11.74 11.00 11.56 12.53 11.54 11.78
13.01 12.73 11.61 11.74 12.07 12.17 12.17
1.38 1.73 1.55 1.39 1.84 1.48 1.56
1.19 1.61 1.30 1.30 1.49 1.90 1.47
2.50 1.19 1.13 1.27 1.09 1.28 1.41
2.20 2.29 1.32 1.63 2.08 1.70 1.87
1.85 1.42 1.00 1.37 1.40 0.93 1.33
2.07 1.91 1.23 1.64 2.07 1.35 1.68
1.85 1.44 1,09 1.31 1.52 1.27 1.38
0.33 0.23 0.48 0.54 0.42 0.52 0.42
0.96 0.88 1.10 1.03 1.36 1.15 1.08
0.93 1.03 1.08 0.98 1.35 1.24 1.10
0.46 0.25 0.47 0.43 0.51 0.61 0.46
1.03 0.81 1.08 1.03 1.40 1.26 1.10
0.38 0.24 0.43 0.44 0.42 0.56 0.41
0 97
0.77 0.75 0.56 0.68 0.58 0.60 0.66
0.72 0.70 0.59 0.70 0.49 0.64 0.63
0.72 0.82 0.59 0.70 0.55 0.60
0.21 0.13
1.22 0.46 0.54 0.58 0.82
1.04 0.42 0.52 0.50 0.56
:
16 08 12.26
11.19 6.19 11.18 11.38 7
...
5.25 5.15 5.05 5.05 5.25 5.13
... 5.47 5.71 5.47 5.55 5.44 5.52
c
10:75 10.08 10.89 11.84 10.80 10.87
-
...
1.44 0.95 1.79 2.09 1 17 1.40
ii:So
10.99 10.96 11.12 11.88 11 35
...
1.10 0.83 1.29 1.41 1.02 1.13
...
Hydrogen-Ion Concentration (pH) b 5.05 5.23 5.12 5.32 5.10 5.38 5.18 5.17 5.08 5.12 5.51 4.98 5.35 5.10 5.25 5.03 5.55 4.91 5.07 5.27 5.22 5.54 5.06 5.29 5.07 5.35 Soluble Ash 13.00 13.44 ii:i s 13:72 12.59 12.68 11.10 11.48 10.87 11.69 11.69 11.76 11.86 11.96 12.63 13.06 11.91 11.53 11.15 11.73 11.25 11.92 11.65 12.35 11.91 12.20
...
...
2.32 0.99 2.02 2.78 1.18 1.86
7
...
0.24 0 44 0 37 0 41 0 58 0.41
...
... 0.84
1.07
1.06
1.41 1.30 1.14
...
...
6’24 0 36 0.42 0.35 0.51 0.38
...
Silica (SiOt)
...
1.90 1.18 1.35 2.21 1.23 1.57 -Magnesium
1.66
...
0.92 1.04 1.00 1.34 1.16 1.09
0.41
0.56 0.40
7
... 0.69 0.68 0.77 0.90 0.72 0.84 0.63 0.60 0.60 0.51 0.61 0.71 0.71 0.67 0.69 0.66 0 . 5 4 0.46 0 . 5 5 0.51 0.50 0.58 0.59 0.60 0.60 0.61 0.63 0.67 0.63 0.66 0.61 c Chlorine (Cl) ,.. ... 3.17 2.66 ... ... 0.24 b.24 0.24 0.17 0.12 1.69 1.66 0.12 0.09 0.16 0.12 0.17 0.23 0.17 1.87 1.84 0.17 0.17 0.21 0.20 0.21 0.42 0.37 1.69 1.50 0.27 0.26 0.30 0.23 0.23 0.18 0.52 0.36 0.52 0.25 0.33 0.25 2.46 1.69 0.18 0.15 2.32 1.80 0.20 0.15 0.17 0.15 0.17 0 . 2 2 0.26 0 . 2 0 0 . 1 7 0 . 2 7 0.27 0.21 2.20 1.86 b Since pH values are logarithmic and may not be averaged like ordinary numbers, they were converted to moles per liter. tlie results were reconverted to pH units. 0.71 0.63 0.76 0.53 0.70 0.67
0.83 0.65 0.75 0.57 0.63 0.69
0.71 0.71 0.58 0.70 0.44 0.66 0.63
0.72 . 0.80 0.51
...
0.73 0.61 0.67 0.53 0.63 0.63
ages 3.31 per cent for the 6-year period, varying from a n increase of 8.43 per cent for the 1929 crop to a decrease of 3.6 per cent for the 1932 crop. The lower soluble-ash percentage in the limed 1932 plats may be traced to the much larger yields of green immature tobaccos. These contain increased amounts of organic constituents as shown by the high acid and nitrogen values. A computation of the absolute amount of ash in the limed tobaccos will show that this quantity is larger than in the nonlimed tobaccos.
-
0.20
0.90 1 07 1 02 1.37 1.22 1 10
0.66
0.16 0.31 0.26 0.61 0.50 0.21 0.67 0.56 These values weie averwed and
The calcium content of the tobacco produced on the limed portion of the plats averages about 21 per cent greater than that produced on the nonlimed portion, with the exception 01 the NPK (muriate) plat of the 1932 crop. This increase in calcium content is accompanied by a slight increase in potassium, which is not in accord with Anderson’s findings (1). Furthermore, such a decrease as found by Anderson (1) might have been predicted from McIntyre’s work (SI). The largest calcium content was found in the tobacco from
1034
INDUSTRIAL AND ENGINEERING CHEMISTRY
VOL. 29, NO. 9
the plat to which muriate was applied. This may have been The average sulfur content of tobacco from the limed part due to the solvent action exerted by potassium chloride on the of the plats was found to be about 25 per cent less than that calcium in the soil, and would be similar to the solvent action from the nonlimed part. The lowest sulfur content was found of potassium chloride onmagnesium, postulated by Garner(l2). in that tobacco grown on the plat receiving the NPK (muriate) The magnesium content of tobacco produced on the limed formula. It would appear that chlorine tends to depress the portion of each plat is greater than that from the nonlimed absorption of sulfur by the plant. These results corroborate portion. The average increase amounted to about 168 per those obtained by Garner (IS). cent. The magnesium content of all these tobaccos, with the With the exception of the plat t o which the a/4 NPK (ampossible exception of those from the nonlimed plats in 1929, monium sulfate) formula was applied in the 1933 crop, the was sufficient to prevent magnesium hunger, if results obchlorine content of the tobacco from the nonlimed Dart of each tained by Garner of the plats was found to b e equal to ( l a ) are used as a or greater than that from limed porRAINFA,!F28 S E A S O N criterion. tions. The average decrease due to 1655 INCHES With the excepliming was about 16 per cent. Garner tion of the plat to ( I S ) showed that the greater the which a decreased amount of chlorine available to the 1929 S E A S O N RAINFALL lPl0 INCHES amount of potastobacco plant, the greater the amount sium was applied, absorbed. His results are supported there is little differby u n p u b l i s h e d work from this 1930 S E A S O N ence in the potas1a b o r a t o r y and are corroborated RAINFALL 12.59 INCHES sium content of the furthermore by the present data, tobacco from the since the chlorine content is higher two portions of the in tobaccos from the plat to which 1 9 3 1 S E A S O N 5 4RAINFALL 21.11 INCHES plats. I n the case NPK (muriate) was applied. of the plat to which A resume of these relations shows the decreased (a)that the percentage of nitrogenous 1932 SEASON amount of potasconstituents, organic acids, calcium, RAINFALL 10.97 INCHES sium was applied, magnesium, potassium, and phos2the average increase phorus in the cured tobaccos in0in potassium con1933 S E A S O N creases if dolomitic l i m e s t o n e i s 4R A I N F A L L 16.93 INCHES tent with liming was applied to the soil, and (b) that the about 20 per cent. hydrogen-ion concentration and the This increase is not percentages of nicotine, soluble carboin agreement with hydrates, petroleum ether extract, LENGTH O F GROWING SEASON I N W E E K S the results of Andersilica, chlorine, and sulfur in the son (1) and McIncured tobacco decrease if dolomitic FIGURE1. RAINFALL, IN INCHES PER WEEK,FROM ONEWEEK TO ONE WEEK PRIORTO LAST PRIORTO TRANSPLANTING tyre (31) as pointed limestone is applied. PRIMING out above. Garner (121, h o w e v e r , Effect of Amount and Distribution of Rainfall showed that slightly more potassium is taken up from potassium sulfate than from potassium chloride. Previous publications (8, 9) showed that differences in the The average silica content of the tobacco grown on the nonchemical composition of tobaccos may be attributed to varylimed portion of the plats is about 18 per cent greater than ing amounts and distribution of rainfall. T o obtain a full that grown on the limed portion. Silica content is variable understanding of the chemical data presented in this paper as from plat to plat and from year to year. It ranges from 0.95 correlated with liming, it is necessary to interpret them in the to 2.78 per cent for the tobacco from the nonlimed plats and light of the rainfall conditions prevailing during the period from 0.83 to 2.50 per cent for the tobacco from the limed plats. when the tobacco plants were growing and maturing. The It is likely that a t least some portion of the material deterdetailed rainfall data are therefore presented in Table 111. mined as silica was obtained from sand and foreign material. The crop data and the dates of transplanting and priming are It is practically impossible to remove all such adhering mategiven in Table IV. The rainfall occurring in the period berials from the tobacco tissues. ginning one week prior to transplanting and ending one week Hoagland (19) points out that the importance of silica in prior to the end of priming may be called the effective rainfall plant growth has long been a controversial matter. This is (Figure 1). The total rainfall for the two wet seasons and especially true of the relation of silica to phosphate nutrition. of the drier seasons was as follows: three Loew ($7) stated that as early as 1880 E. Wolff and Rittenliausen proposed independently that silica, if present, played Dry Seasons Wet Seasons Rainfall, Rainfall, a role in the dying-off process. The plants grown on the limed Year inches Year inches portions of the plats matured more slowly or remained green 19.10 1930 12.59 1929 21.11 1932 10.97 1931 longer than those grown on the nonlimed portion. 16.93 1933 The content of the oxides of iron and aluminum is rather Av. 20.11 Av. 13.50 small and averages 0.22 per cent. Deviations from this averThe amount of rainfall during the 1928 and 1933 seasons age due to liming or to differences in fertilization or seasons are was about normal, but its distribution was poor. The cool probably not significant. cloudy weather near the end of the 1933 season retarded the The phosphorus content of the tobacco from the limed and maturing of the crop. I n 1930 and 1932 the rainfall was nonlimed portions averages about the same. I n some seasons, deficient, and they may be termed dry seasons. The prehowever, the variation between the two portions is large cipitation during the growing seasons of 1929 and 1931 was enough to be significant, and the decreased phosphorus content excessive, and they may be regarded as wet seasons. Exof some of the crops might be interpreted as being partly recessive rainfall, especially if it occurs a t a time when the sponsible for their lack of maturity.
I
-JL,
SEPTEMBER, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
1035
leaves should be maturing, induces a condition known as second growth (9, page 1216). Extensive second growth occurred during 1931 and adversely affected the crop. Since the range of fertilization in the experiments of the 1928 crop was limited, the results pertaining to it are not included in the following discussion. The 1929 crop is a typical wet-weather crop. The 1931 crop will also be classified as a wet-weather crop because its characteristics, with the exception of its lack of maturity, are predominantly those of a wetweather crop. In flue-cured tobacco, low sugar and high nitrogenous content, especially high amino nitrogen content, is definitely associated with lack of maturity. The 1930, 1932, and 1933 crops will be considered as dry-weather crops. The long season and poor distribution of rainfall in 1933 imparted to the tobaccos of that season the characteristics of a dry-weather crop. The high sugar and low nitrogenous constituents of the 1930 crop are due to the rather complete maturity of this crop, attained because of the hot, dry weather throughout the priming season. I n this period the plants made little or no growth. The other characteristics of this crop, however, are predominantly those of a dry-weather crop. The average nitrogen content of the dryweather crops is considerably above that of the w e t - w e a t h e r crops. The increase amounts to about 12 per cent in the case of tobaccos from the nonlimed soils and about 28 per cent in thosefrom the limed soils. Liming tends to accentuate this increase in nitrogenous constituents during dry seasons. The inconsistent results in the wet-weather 1931 crop should be pointed out. This crop possessed a higher nitrogen content than the dryweather crop of 1930, because of a difference in maturity of the two crops at harvest time. The data for the a-amino nitrogen, watersoluble nitrogen, and nicotine follow the trends shown by the total nitrogen. These data p e r t a i n i n g to nitrogen content, in general, corroborate the previous findings with c i g a r e t t o b a c c o s (9)and those of Anderson ( I ) with cigar tobaccos. The average sugar content of those crops produced during dry years is somewhat less than that of those produced during wet years. Again it may be recounted that the wet-weather 1931 crop contains less sugar than the dry-weather 1930 crop. The total acid content of those crops produced during dry seasons is considerably greater than for those produced during wet seasons. The practically identical total acid content of the 1930 and 1931 crops constitutes a n exception The ionizable acidity as measured by the p H of the crops produced during wet seasons is not significantly different from that of crops grown during dry seasons. The average petroleum ether extract content is about 24 per cent higher in tobaccos produced during dry seasons. This condi-
INDUSTRIAL AND ENGINEERING CHEMISTRY
1036
tion was to be expected and its significance has been discussed at length in a previous publication (9). The average results for the soluble ash of the tobaccos produced during the wet and dry seasons do not differ significantly. The average potassium content is about 18 per cent greater in tobaccos produced during the wet seasonsJ ‘Onfirming the findings of several investigators (1, 9, 17). The relation of varying potassium content to weather conditions, and its influence upon the content of other constituents was discussed previously (9).
VOL. 29, NO. 9
Lipman and his collaborators (24, 86,d6), Ginsburg and Shive (15), and Morse (32)showed that the percentage of nitrogen in leguminous plants is increased if the soil is limed. Blair and McLean (4) obtained an increased percentage of nitrogen in the grain and stover of corn from liming. Anderson’s results with the tobacco plant (1) showed a decrease in the percentage of total nitrogen, nitrate nitrogen,
nicotine, sulfur, and potassium with liming. Soficek (is),Greaves ( 7 ) , and Lyon ($9) demonstrated that the addition of lime tends to free the nitrogen in the soil. Lipman (84) pointed out the definite possibility of depleting the nitrogen supply of the soil by the addition of lime, unless legumes are frequently used in the crop rotation.
PER ACREAND DATESOF TRANSPLANTINQ AND HARVESTING TABLEIV. YIELDIK POUKDS
N P K 7 (hmmonium Sulfate) ---Average--No lime Lime No lime Lime 803 1293 964 1327 735 970 947 1111 1385 1133 1136 1165 1190 1525 1301 1501 884 1296 864 1233 1121 1457 1124 1387
----Z/d
Crop 1928 1929 1930 1931 1932 1933
’/*K--
-NP No lime
Llme
90s 890 1165 860 1003
ii97 952 1442 946 1269
965
1161
Av.
NPK (Muriate) No lime Lime 1160 1543 1117 1257 1330 1267 1530 1617 856 1421 1138 1436 1190
1423
NPK (Mixed N ) No lime Lime
---XPK-
825 948 1245 879 1181
1152 1500 1209 1361
N o lime 930 1150 1125 1375 839 1179
1016
1224
1100
900
The average calcium content is considerably increased in tobaccos produced during dry seasons. This increase is about 23 per cent in tobaccos from nonlimed plats, and about 12 per cent in tobaccos from limed ones. Similar results were obtained with cigar tobaccos by other investigators (1, 17). The average magnesiom content of the tobacco from the nonlimed plats is about 38 per cent higher; that from the limed plats is about 27 per cent higher in tobaccos grown during dry seasons. Anderson (1) obtained similar results with cigar tobaccos. The figures for the silica content are inconsistent and apparently do not warrant any correlation with the amount of rainfall. Anderson ( I ) , however, found consistently higher silica during the wet season. The phosphorus content was about 21 per cent higher in tobaccos produced during wet seasons. These results do not corroborate Anderson’s findings with cigar tobaccos (1). With the exception of the 1930 crop, the combined oxides of iron and aluminum are somewhat higher in tobaccos grown during dry seasons. The sulfur and chlorine content are somewhat higher in tobaccos grown during dry seasons. The rainfall data show (a) that increased rainfall tends to increase the potassium, phosphorus, and sugar content of cured tobaccos, and (b) that decreased rainfall tends to increase the percentage of nitrogenous constituents, nicotine, organic acids, petroleum ether extract, iron and aluminum, calcium, magnesium, chlorine, and sulfur in cured tobaccos.
Interpretation of Data Any attempt to interpret the relations of the above data in the light of the voluminous published reports of experimentation pertaining to the application of calcitic or dolomitic limestone to plants is of limited value. This is due to the fact that many of these deal only with increased yields resulting from the application of lime. Others deal with the effect of lime in modifying the course of various plant diseases, either of nutritional or parasitic origin. Inmost of this work, chemical analyses of the crops produced were not made, and in most cases where analyses were made, they included the ash constituents only. The effect of the increase of available calcium and magnesium in the soil upon the organic composition of the plant has been treated to a limited extent only by a few investigators:
Lime 1145 1230 1320 1423 1291 1420 1305
1020
1279
1063
Date of Transplanting May 18 May 22 May 14 May 15 May28 May 15
Date of Priming Aug. 6-Sept. 10 July 29-Aug. 27 July2l-Aug. 19 Aug. 14-Sept. 7 Aug. 24-Oct. 19 July24-Sept. 12
1285
Truog (46) and Haas (16) added lime to the medium in which the plant was grown and obtained a decrease in the hydrogenion concentration of the plant juices. Clevenger (@, however, found that the hydrogen-ion concentration of the leaves and tops of oats, soybeans, and cowpeas increased with liming, whereas that of the roots decreased. By means of a large number of ash and nitrogen analyses of plant tissues Parker and Truog (38) showed that a high nitrogen content is associated with a high calcium content and a slightly increased phosphorus content. They are of the opinion that protein metabolism is the chief source of organic acids in plants, and that the excess acids are controlled through their neutralization or precipitation by calcium. This view of the mechanism for controlling the organic acids produced as a by-product is supported by the experimental data of Kelley and Cummins ( W l ) , as pointed out by Thomas (46). Kelley and Cummins found that the leaves of Citrus affected with mottling were abnormally low in calcium and high in free nonionized acid. On the other hand, Thatcher (44)and Gerhardt (14) believe that the deposition of calcium oxalate crystals is a means for control of excessive calcium in plant juices. The work of Astruc (8), however, gave evidence that the disappearance of acids is due mostly to respiration and esterification. The assumption of Parker and Truog (58)that acids are a product of the decomposition of proteins is the older view and was generally held by plant physiologists during the later part of the nineteenth century. This belief, in the light of much recent work (28, 28, SO, 41), has been replaced by the view that plant acids arise as a result of incomplete oxidation of carbohydrates. Richards (41) believes that the carbohydrates form unstable unions with the living protoplasm which, by intramolecular resDiratory processes, break down, giving. _ _ organic _ acids as by-products. Nightingale (S6), Hartwell (18), and Schimper (@), using various kinds of dants. showed that carbohvdrates freauentlv accumulate in theiissues of plants deficient in calcium. N;ght& gale (S5), Garner ( l a ) , and Reed (39, 40) showed that chlorophyll formation is interfered with if the supply of calcium to the plant is limited. Nightingale (36)pointed out that one of the principal uses of carbohydrates is in protein synthesis, and Nightingale (86, 87), Kraus (as), and Eckerson (11) showed that carbohydrates may accumulate if the plant has no external supply of available nitrogen. I n the present experiments the outstanding effects of lime are noted in the content of nitrogenous constituents, carbohydrates, organic acids, and calcium. The figures in Table I1 contrast the chemical composition of tobaccos grown on heavily limed soil with that of those grown on nonlimed soil. The limed soil became more alkaline and its content of calcium and magnesium increased. The tobacco produced on the limed soil possessed an average total nitrogen content of 2.82 per cent as compared with 2.67 in the tobacco from the nonlimed soil. Each ot‘the nitrogen constitu-
SEPTEMBER, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
enB determined was greater in the tobacco from the limed soil, and the amino nitrogen exhibits a greater increase than the other nitrogen fractions. The average sugar content, however, of tobaccos grown on the limed plats is much less than of those on the nonlimed ones. There is no evidence to indicate that conditions were less favorable for the occurrence of photosynthesis in the tobacco produced on the limed plats. We may assume, therefore, that the amount of carbohydrate synthesized by the plants grown on limed soil is probably as great as that synthesized by those on the nonlimed soil. The average quantity of organic acids in the tobaccos grown on the limed soil was 48 per cent greater than that in the tobaccos from the nonlimed soil. This increase came either directly or indirectly a t the expense of the carbohydrates. The calcium content of the tobacco produced on the limed soil is over 21 per cent greater than in the tobacco from the nonlimed soil. The organic acids are probably combined with calcium, forming compounds not readily used in respiration. A consistent picture of the effects induced by liming upon the chemical composition of plants might seem impossible in the light of the conflicting points of view and of the apparent disagreement in the data from the investigations cited. We must bear in mind, however, that some of the conclusions cited are based upon experimental data involving determinations of a limited number of chemical constituents. Furthermore, many of these data were obtained under a restricted range of environmental conditions. The wealth of experimental data in the present paper, obtained under a wide range of weather conditions, suggests a plausible interpretation of the effects induced by liming and one which reconciles the present results with the widely divergent findings of others. This interpretation is based upon the postulation of the sequential occurrence of the following phenomena. The existence of these phenomena is either generally accepted, or finds support in the literature cited or in the present experimental data: (a) Dolomitic limestone accelerates the decomposition of organic matter in the soil, making an increased supply of nitrogen available to the plant. ( b ) I n response to this increased supply of nitrogen and the more alkaline condition of the soil, the plant absorbs a greater quantity of nitrogen. (c) This increased amount of nitrogen in the plant results in increased protein formation. (d) Protein is built up a t the expense of the carbohydrates which results in a decreased carbohydrate content. ( 9 ) An accompanying increase in acid content should occur, and it is immaterial whether the acids come from the splitting of the proteins formed or from the incomplete oxidation of carbohydrates. (f) The increased amount of calcium in the plant could combine with some of the acids formed, resulting in the formation of the relatively insoluble calcium salts of these acids. It is unnecessary to postulate whether the calcium is present to precipitate the acids from the field of action or whether the acids are required to remove the excess calcium from the plant juices. It is more probable that increased amounts of both calcium and acids are present as a result of liming, and that they combine to form relatively insoluble, immobile compounds. Finally, consideration may be given to a general interpretation of the physiological effects of liming as applied to cultural practices with flue-cured tobaccos.
Relation between Chemical Composition, Maturity, and Quality The virtue of the present experiments on liming lies in the fact that they serve to single out and to emphasize the more important chemical factors that relate to maturity and quality in flue-cured tobaccos. It becomes possible to formulate the following general picture of the important chemical considerations in the production
1037
of flue-cured tobacco when the results of this paper are viewed in the light of the earlier work on the relation of stalk position and rainfall to quality. The composition of good cigaret tobaccos was given in previous papers (8, IO) : it was pointed out (9)that the quality of cigaret tobacco improves as the soluble carbohydrate content increases. It was also established that a correlation exists between the chemical composition of tobacco leaves, the position a t which the leaves are borne on the stalk, and the quality of the cured product. Tobaccos of best quality for cigaret manufacture are produced along the median region of the stalk, and are high in soluble carbohydrate content with a correlated relatively low total nitrogen content. It was also shown that neither a high nor a very low total nitrogen content is associated with tobacco of best quality. I n the earlier papers analyses for ash constituents were not given. If we consider the figures for the content of nitrogenous constituents, soluble carbohydrates, and total acids given previously (8, I O ) as typical of good cigaret tobaccos, an inspection of Table I1 will show that the data for the tobaccos produced on the nonlimed portions more nearly approach these figures than the data for the tobaccos from the limed portions. Certain general effects of liming are apparent in all of the crops, with the exception of the 1929 crop which needs special consideration. The tobaccos from the limed soils were lower in carbohydrates and higher in nitrogenous constituents and acids than those from nonlimed soils. They were much poorer in quality, and their market value was less than that of the tobacco grown on the nonlimed plats. Thus it appears that the decreased quality of the tobacco from the limed plats can be correlated with its lower sugar content and its greater content of nitrogen and total acids. Confirmation of this criterion for quality is found in the fact that the composition of nonlimed tobaccos borne near the top of the stalk approximates that of the limed tobaccos considered here. Tobaccos produced near the top of the stalk, as shown previously (Q), are of poorer quality. Such tobaccos from near the top of the stalk are highest in amino nitrogen (9) and are of a green immature nature. A high amino nitrogen content is associated with inferior quality. Unpublished work by this laboratory indicates that it is also definitely associated with greenness or lack of maturity. Since their amino nitrogen content is high, it is evident that the poorer quality of tobaccos from limed soils can be attributed to their lack of maturity. Furthermore, a low carbohydrate and high nitrogen content do not seem conducive to the attainment of maturity. If full maturity, which is essential for good quality, is to be attained, it is necessary to limit the amount of nitrogen available to the plant after it has reached its normal size. The lack of available nitrogen results in decreased formation of proteins and of their degradation products, and a concomitant building up of carbohydrates. If calcium is present in larger quantity than is needed for normal functioning, it will probably combine with the organic acids which originate from protein formation and degradation. If it is not available, the acids will be used up in respiration. Calcium absorption takes place principally during the early stages of the plant’s life when it is most vegetative and a large proportion of the calcium is found in the basal parts of the plant (5,9). I n fluecured tobacco harvested by the priming method, the leaves from near the base of the stalk are removed first, a t a time when the leaves near the top of the plant may still be in a very vegetative condition. We would expect to find the greatest proportion of calcium and organic acids in these first primed leaves. Data given in a former publication (9)demonstrate this to be true. They also show that the acid content of tobaccos from the upper part of the stalk is higher than that of those from the median portion. The content decreases rapidly from the bottom toward the middle and slowly from the
1038
INDUSTRIAL AND ENGINEERING CHEMISTRY
middle towards the top of the stalk. This indicates that the acid formed in the mature leaves harvested from the median portion is used up in respiration. I n the tobacco from the upper part the acids not in mineral combination are in organic combination. Some of them are in the form of amino acids and some are combined with the increased amount of nicotine occurring in the upper leaves (9). These regularities are evident in five of the six crops. The exceptional 1929 crop requires further consideration. The tobacco produced in 1929 possessed the best quality of the six crops studied. The nitrogen data of this crop, with the exception of the a-amino nitrogen for the tobacco produced on the limed portions, are similar to the nitrogen data given for good tobaccos in the previous papers (8, I O ) . The tobacco grown on the limed parts of the plats in 1929 possesses a higher sugar content than any of the other samples of tobacco from limed soils that were analyzed. This higher sugar content and the average nitrogen content of the tobacco from the limed portions in this crop are evidence that it was muchmore mature than the tobaccos produced on limed soil during any of the other five seasons. The a-amino nitrogen and acid content, however, of the tobaccos from the limed soil in this 1929 crop are both high, indicating that maturity was not so complete as in the tobacco from the nonlimed soil.
Influence of Weather and Priming Practices on Quality I n the light of the chemical changes in tobacco associated with liming considered in the preceding section, attention may be focused upon modifications in quality that occur as the result of liming, of variation in weather conditions, and of maturity of the leaves at time of priming. No attempt will be made to evaluate the several factors quantitatively. The crops from each of the six years will be considered separately to illustrate the relative importance of each of the above variables in determining quality. Both the total amount of rainfall and its seasonal distribution profoundly modify the length of the growing season and the quality of the crop produced. During the entire 1929 growing season (Figure 1) and during the first two-thirds of the 1930 growing season the rainfall was plentiful and was well distributed. The facts that each of these crops was grown in the short period of 97 days and that the yields were entirely satisfactory show that the weather conditions were conducive to continuous and rapid development of tobacco. I n the case of these two crops much of the nitrogen applied with the fertilizer was utilized by the growing plants. I n the 1929 crop the remainder was lost by leaching, and in the 1930 crop it was not absorbed because of lack of rainfall. When the plants had attained their normal size, the leaves matured. I n both cases nitrogen was not available within the plant, and protein formation was checked. Consequently carbohydrates increased and ripening occurred. The growing seasons of 1928,1932, and 1933 had a length of 115, 144, and 120 days, respectively (Figure 1). The rainfall was poorly distributed during both the 1928 and 1933 seasons. Growth was retarded during the rather long periods of deficient rainfall, and rapid growth occurred whenever rainfall made it possible. In the case of both of these crops a period of rapid development came a t a time when the plants should have been maturing. As a result, a pronounced second growth occurred in the 1928 crop, and a less marked one in the 1933 crop. If the nitrogen not required to give the plants their size had been leached out by timely rains, the leaves probably would have matured in a more normal fashion and the cured tobacco would have been better in quality. The smallest yields were obtained in 1932 when the rainfall, totaling approximately 11 inches, was deficient throughout
VOL. 29, NO. 9
the entire growing season. Consequently the development of the plants was greatly retarded, the growing season extending over a period of 144 days. Little nitrogen was lost by leaching. Nitrogen was continuously taken up by the plants as moisture conditions permitted. Priming was delayed in ail effort to permit the development of maturity. However, the greater proportion of the leaves never matured. Analyses showed that the cured leaves had a high content of amino nitrogen and a low content of sugars. Liming had the effect of increasing yields more in this crop than iC any of the others. It would appear that the greater effectiveness of liming was due to the longer period during which it acted (20). Although the rainfall in 1931 (Figure 1) was plentiful, its poor distribution resulted in the production of tobaccos whose chemical composition was somewhat characteristic of crops produced during dry seasons. The rainfall occurring from late in May to July 25 was deficient, and poor growth of the plants resulted. This period was followed by 11.6 inches of rain during the 30-day interval from July 25 to August 23. A very pronounced second growth developed. If weather conditions had been such as to permit this crop to remain in the field sufficiently long, the leaching and utilization of nitrogen in protein synthesis would have exhausted the available supply of nitrogen in the soil. A crop of better quality could have then been harvested. Instead, it was necessary to prime the tobacco while its amino nitrogen content was abnormally high. The leaves when primed weye thicker and larger than normal, and the yield was large although the quality was poor. The data in hand indicate that such weather conditions and fertilization practices as will sustain continuous and rapid development of the tobacco plant for approximately 60 days after transplanting are essential, if flue-cured tobacco of good or excellent quality is to be produced. It is also essential for the development of maturity that these conditions should be such that the nitrogen supply becomes exhausted as the end of the growing season approaches. Any practice that makes nitrogen available to the tobacco, when the leaves should be maturing, is deleterious. Thus the growing of legumes in rotation with flue-cured tobacco has a limited usefulness. The reason lies in the fact that the organic nitrogenous residues remaining in the soil from the leguminous crop may not become sufficiently exhausted to permit the tobacco to ripen or mature properly. The leaves of tobacco grown on such soils, when , primed and subjected to flue curing, do not develop the desirable colors. This adverse condition may be expected to be accentuated as the result of the application of excessivequantities of lime. It is realized that calcium and magnesium in quantities above the deficiency level are necessary for the growth of tobacco. These minimal quantities of calcium and magnesium must be provided for in good fertilization practice. The present data indicate that one of the principal effects of the application of excess limestone is concerned with the increasing of the amount of nitrogen available and the prolonging of the period of availability of the nitrogen supply in the soil. As a result the leaves mature more slowly or fail to mature, and there is a lack of suitable balance between nitrogenous and carbohydrate constituents in the cured tobaccos. Tobaccos with these characteristics are not the most desirable for the manufacture of blended cigarets.
Acknowledgment The authors acknowledge with gratitude the help of J. A. Hall and E. P. Jones, who carried out some of the determinations on the 1929 crop and assisted in related work preliminary to this program. Grateful acknowledgment is also made to E. G. Moss and James Bullock, of the Oxford Experiment Farm, who supervised the growing, harvesting, curing, and
SEPTEMBER, 193i
INDUSTRIAL AKD ENGINEERING CHEMISTRY
grading of the tobacco used in this investigation. They also collected the weather data presented in Table 111.
Literature Cited (1) Anderson, P. J., Swanback, T. R., and Street, 0. E., Conn. Agr. Expt. Sta., Bull. 311 (1929). (2) Assoc. Official Agr. Chem., Methods of Analysis, 2nd ed., 1925. (3) Astruc, A,. Ann. Sei. Nat. Botan., [8] 17, 1-108 (1903). (4) Blair, A. W., and McLean, H. C., Soil Sci., 1, 489-504 (1916). (5) Burd, J. S., J. A g r . Research, 18, 51-72 (1919). (6) Clevenger, C. B., S o i l Sei., 8, 227-42 (1919). (7) Creaves, J. R., and Carter, E. G., Ibid., 7, 121-60 (1919). (8) Darkis, F. R., Dixon, L. F., and Gross, P. M., IND. ENQ.CHEM., 27, 1152-7 (1935). (9) Darkis, F. R., Dixon, L. P., Wolf, F. A., and Gross, P. M., Ibid., 28,1214-23 (1936). (10) Dixon, L. F., Darkis, F. R., Wolf, F. A., Hall, J. A., Jones, E. P., and Gross, P. M., Ibid., 28, 180-9 (1936). (11) Eckerson, S. H., Botan. Gaz., 77, 377-90 (1924). (12) Garner, W. W., McMurtrey, J. E., and Bowling, J. D., J. Agr. Research, 40, 145-68 (1930). (13) Garner, W. W., McMurtrey, J. E., Bowling, J. D., and Moss, E. G., Ibid., 40, 627 (1930). (14) Gerhardt, K., Naturwissenschaften, 8, 41-3 (1920). (15) Ginsburg, J. M., and Shive, J. W., SoiE Sei., 22, 175-97 (1926). (16) Haas, A. R. C., Ibid., 9, 341-69 (1920). (17) Haley, D. E . , Nassett, E. S., and Olson, O., Plant Physiol., 3, 185 (1928). (18) Hartwell, B. L., R. I. Agr. Expt. Sta., Bull. 165 (1916). (19) Hoagland, J. R., Ann. Rev. Biochem., 1, 618-36 (1932). (20) Karraker, P. M., Soil Sci., 24, 147 (1927). (21) Kelley, W. P., and Cummins, A. B., J. Agr. Research, 20, 161-91 (1920). (22) Kostychev, S., “Plant Respiration,” pp. 133-42, Philadelphia, P. Blakiston’s Son & Co., 1927.
1039
(23) Kraus, E. J., and Kraybill, € R., I.Oreg. Agr. Expt. Sta., Bull. 149 (1918). 1241 LiDman. J. G.. Soil Sci.. 9. 83-114 119201. (25) Lipman, J. G., and Blair, A. W., Ibid., 4, 71-2 (1917). (26) Ibid., 9, 375-92 (1920). (27) Loew, Oscar, U. S. Dept. Agr., Bur. Plant Ind., Bull 45, 20 (1903). (28) Long, E. R., Plant World, 18, 261-72 (1915). (29) Lyon, T. L., Bizzel, J. A., Wilson, B. D., and Leland, E. W.. Cornell Univ. Agr. Expt. Sta. Mem., 134, 5-72 (1930). (30) McDougal, D. J., Long, E. R., and Brown, J. G., Ph&oZ. Researches, 1, 289-325 (1915). (31) McIntyre, W. H., Shaw, W. A t . , and Young, J. B., J. Agr. Sci., 20, 499-510 (1930). (32) Morse, F. W.; Mass. Agr. Expt. Sta., Bull. 161 (1915). (33) Moss, E. G., S. Am. SOC.Agron., 21, 137 (1929). (34) Moss, E. G., U. S. Dept. Agr., Tech. Bull. 12 (1927). (35) Nightingale, G. T., Addoms, R. M., Robbins, W. R., and Schermerhorn. L. G.. Plant Phusiol.. 6. 605-30 (19311. (36) Nightingale, G. T., and Robbinsr W. R.; N. J. Agr. Expt Sta., Bull. 472 (1928). (37) Nightingale, G. T., Schermerhorn, L. G., and Robbins, W. R., Ibid., 461 (1928). (38) Parker, F. W., and Truog, E., Soil Sei., 10, 49 (1920). (39) Reed, H. S., Ann. Botanu, 21. 5 0 1 4 3 (1907). (40) Reed, H . S.,and Haas,-A. R . C., Univ. Calif., Tech. Paper 4 (1923). (41) Richards, H. M., Carnegie Inst. Wash. Pub. 209 (1915). (42) Schimper, A. F. W., Flora, 73, 207-61 (1890). (43) Sobcek, Jar., Listy Cukrovar., 46, 651-4 (1928). (44) Thatcher, R . W., “Chemistry of Plant Life,” p. 127, New York, McGraw-Hill Book Co., 1921. (45) Thomas, Walter, Plant Physiol., 5 , 443 (1930). (46) Truog, E., and Meacham, M. R., Soil Sci., 7, 469-74 (1919). RECEIVED June 12, 1937.
THE ALCHYMIST By Thomas Wijck (1617-1677) With No. 81 in the Berolzheimer Series of Alchemical and Historical Reproductions, we present the seventh painting by this artist. The original is in the Art Gallery in La Hague and, like all of Wijck’s paintings, is sombre in style. The room depicted, with its stained glass window, draped curtain, salamander, globe, tattered books, etc., seems to be the same as in his other paintings. The furnace a t the left, with its alembic, crucibles, and other primitive equipment appears to be as usual for those days, probably having been purchased at the E. & A. shop of about 280 years ago.
A detailed list of Reproductions Nos. 1 to 60 appeared in our issue of January, 1936, page 129 and the list of Nos. 61 to 72 appeared ID Janhary 1937 page 74 where also will be found keprodbction NA. 73. Reproduction No 74 appears on page 166 February issue No: 75 on pa.ge 345, March ‘issue, No. 76 0; page 459, -4pnl imue, No.77 on, page 554, May issue, No. 78 on page 710 June issue, No. 79 on page 776, July issue, an6. No. 80 on page 945, August issue.
