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Fo 3
4 -3 NORTH FLORIDA EXPERIMENT STATION HIUMi'I I PA
Quincy, Florida
June 20, 1969
JUL 2 2i
NFES Mimeo Report 69-3
THE EFFECTS OF VARYING POTASSIUM, CALCIUM AND MAGNESIUM LEVE'IN-THE-S`IL-ON--AIEL AND
AND QUALITY OF SHADE TOBACCO
F. M. Rhoadsl
INTRODUCTION
Available research results on fertilizing shade tobacco in North Florida are inadequate
at the present time. A large amount of data has accumulated but it is not useful to farmers
or county extension workers in its present form. This report is an attempt to organize some
of the findings into a serviceable format. The data contained in this report were collected
in 1959, 1960, 1961, and 1962 by Mr. W. D. Woodward, formerly assistant soil chemist at the
North Florida Experiment Station. Although, the material is several years old it should
serve as a guide for potash, calcitic limestone, and dolomitic limestone recommendations.
METHODS
There were 18 treatments in this study replicated three times. All treatments had
300 lb/acre of N and 200 Ib/acre of P205 applied to the soil. Two thirds of the N was
supplied by cottonseed meal and 1/3 by ammonium nitrate. All fertilizer materials were mixed
together before applying 70 percent preplant and 30 percent two weeks after transplanting.
Rates of potassium, calcium and magnesium were reduced after the first year. The following
materials were used as sources to supply the required amounts of K20, CaO and MgO:
Source
Cottonbur ash
Potassium sulfate
Dolomitic limestone
Magnesium sulfate
Calcitic limestone
Nutrient Supplied
K20, CaO, MgO
K20
CaO, MgO
MgO
CaO
Soil samples were obtained from each plot before applying fertilizer and after harvest
in 1959, 1960, and 1962. Samples were collected in 1961 at midseason and after harvest.
Also, samples were obtained at midseason in 1962. These samples were analyzed according to
the procedure set forth in the Florida soil testing program.
,Chemical analyses were made on cured leaves in 1960 and 1961 for three harvest dates.
Nutrients determined were nitrogen, phosphorus, potassium, calcium and magnesium.
Plots contained four rows 22 feet long. Yield and grade were determined from cured
leaves harvested from three rows of each plot.
Dixie Shade was the test variety and was planted on the same land throughout the
duration of the experiment with no rotation program. Soil type was Norfolk loamy fine sand.
-Assistant Soil Chemist, North Florida Experiment Station, Quincy, Florida.
RESULTS
Soil analyses: Soil pH was between 5.6 and 5.8 in most plots in 1959 before treatments
were applied. Levels of P205 ranged from 25 to 39 lb/acre, K20 levels ranged from 332 to
439 lb/acre, CaO levels ranged from 505 to 621 lb/acre and MgO levels ranged from 165 to
221 lb/acre for this sampling date (Table 1). Calcium levels in the soil increased in
relative proportion to amounts applied in treatments (Table 2). Potassium is most subject
to leaching and did not build up in the soil in proportion to amounts applied. Phosphorus
is usually fixed in the soil thus limiting the quantity that can be extracted. Calcium and
magnesium build-up in the soil was limited by leaching, even after continued high appli-
cation. Once the soil contains all of the fertilizer nutrients it can hold against
leaching, any additional nutrients will drain away with excess water. Soil pH was above
7.0 during the growing season in some treatments during 1961 and 1962.
Leaf analyses: (Table 3) In general nitrogen and phosphorus content of leaves
increased from second to eighth priming. Potassium decreased from second to eighth priming.
This suggests that late application of potash might improve leaf grade in upper primings
since grade values usually decline as harvest proceeds upward on the stalk. Potassium and
magnesium uptake vary directly with soil application of these elements but calcium uptake
appears to be inversely related to magnesium uptake. High applications of dolomite may be
undesirable because of this relationship.
Yield and grade: (Tables 4, 5 and 6) Treatment 4 produced the highest average yield
for the four year study. Highest grade and crop value were produced by treatment 6. Since
crop value is the most important criterion for evaluating treatment effects in fertility
studies treatment 6 appears to be slightly superior. Crop index ranged from 1420 to 1616
which is somewhat surprising in view of the large variations in fertilizer applications.
DISCUSSION
The data indicate that shade tobacco can tolerate wide variations in soil levels of
potassium, calcium and magnesium without resulting large changes in yield, grade or crop
index. High magnesium levels in the soil tended to lower the crop index. There were only
two application rates and extractable MgO was adequate at the low level. As K20 application
levels increased crop index increased. An application rate of 400 Ib/acre of K20 appeared
to be adequate. There was very little response to higher applications of calcium. However,
extractable CaO at the lowest rate applied to the soil is considered adequate for shade
tobacco production.
FMR
100 CC
6169
Table 1. Soil analysis results in 1959 before applying fertilizer.
Pounds per Acre
Applied to Soil* Pounds per Acre in Soil Extract (1-8-59)
Treatment K20 CaO MgO pH P205 K20 CaO MgO
1 800 1600 800 5.6 26 366 541 169
2 800 1600 0 5.7 35 344 593 172
3 800 800 800 5.6 39 362 541 198
4 800 800 0 5.8 37 439 560 200
5 800 200 800 5.8 34 390 565 180
6 800 200 0 5.6 30 390 505 221
7 400 1600 800 5.7 25 362 583 165
8 400 1600 0 5.7 28 412 560 176
9 400 800 800 5.7 30 371 546 208
10 400 800 0 5.6 30 396 537 170
11 400 200 800 5.7 29 367 565 199
12 400 200 0 5.8 35 376 518 204
13 0 1600 800 5.8 31 405 621 220
14 0 1600 0 5.8 36 393 569 182
15 0 800 800 5.8 35 378 620 194
16 0 800 0 5.7 37 332 560 158
17 0 200 800 5.6 35 353 513 175
18 0 200 0 5.7 36 333 527 170
*Application rates in 1959 were higher than shown in tables, K20 was applied
at 400, 800 and 1200 Ib/acre, CaO at 800, 1600 and 2400 Ib/acre and MgO at
200 and 1200 Ib/acre. Rates of K20, CaO and MgO shown in tables were applied
in 1960, 1961 and 1962.
Table 2. Soil analysis results in 1962 after harvest at end of test.
Pounds per Acre
Applied to Soil Pounds per Acre in Soil Extract
Treatment K20 CaO MgO pH P205 K20 Ca0 MgO
1 800 1600 800 7.3 147 626 1926 509
2 800 1600 0 7.2 114 618 2173 326
3 800 800 800 7.2 151 555 1357 523
4 800 800 0 6.8 70 611 1348 270
5 800 200 800 6.5 46 646 881 382
6 800 200 0 6.4 46 657 946 266
7 400 1600 800 7.2 119 415 2061 510
8 400 1600 0 6.9 85 404 2024 226
9 400 800 800 6.8 68 390 1287 521
10 400 800 0 6.5 57 391 1366 239
11 400 200 800 6.3 41 371 807 354
12 400 200 0 6.3 46 364 900 229
13 0 1600 800 7.0 109 135 1852 476
14 0 1600 0 6.9 95 137 2220 269
15 0 800 800 6.7 64 154 1194 509
16 0 800 0 6.5 62 119 1511 231
17 0 200 800 6.1 47 166 918 366
18 0 200 0 6.0 42 136 872 184
Table 3. Leaf analysis results (percent of each element) 1961.
Pounds per Acre
applied to soil Second Priming Eighth Priming
Treatment K20 CaO MgO N P K Ca Mg N P K Ca Mg
800
800
800
800
800
800
400
400
400
400
400
400
0
0
0
00
0
0
1600
1600
800
800
200
200
1600
1600
800
800
200
200
1600
1600
800
800
200
200
800
0
800
0
800
0
800
0
800
0
800
0
800
0
800
0
800
0
4.10
4.17
4.13
4.54
4.50
4.35
4.13
4.05
4.26
4.32
4.47
4.40
4.27
4.26
4.03
4.21
4.27
4.42
0.11
0.14
0.12
0.13
0.13
0.10
0.10
0.10
0.09
0.14
0.16
0.12
0.08
0.13
0.09
0.12
0.13
0.13
5.77
5.60
5.59
5.44
5.66
5.80
5.01
5.30
5.47
5.52
5.06
5.40
3.59
3.84
4.47
4.20
4.14
4.45
1.09
1.83
0.80
1.65
1.60
1.22
1.31
1.92
1.35
1.98
0.46
1.65
1.99
1.97
1.37
2.75
0.70
2.19
1.12
0.83
1.26
0.51
0.95
0.71
1.45
0.59
1.12
0.54
1.58
1.06
1.93
0.88
2.12
0.94
1.62
1.14
4.81
4.85
5.21
5.08
5.34
5.12
5.06
5.06
5.17
5.26
5.22
5.21
5.06
5.13
5.24
5.25
5.32
5.40
0.20
0.18
0.16
0.13
0.18
0.13
0.15
0.17
0.15
0.17
0.18
0.18
0.18
0.15
0.15
0.14
0.16
0.15
3.83
4.15
3.98
4.00
4.12
4.20
3.35
3.40
3.53
3.72
3.70
3.98
2.82
2.88
2.65
2.78
3.03
3.03
2.21
2.74
1.51
2.26
1.23
2.04
2.47
3.30
2.17
2.79
1.32
2.11
2.47
3.37
2.12
2.78
1.62
2.42
1.00
0.58
1.13
0.69
1.29
0.83
1.13
0.72
1.29
0.73
1.47
0.79
1.14
0.77
1.61
0.86
1.46
0.92
Table 4. Yield by years (Ib/acre).
Pounds per Acre
applied to soil Year
Treatment K20 CaO MgO 1959 1960 1961 1962 Average
1 800 1600 800 1756 1782 2363 2352 2063
2 800 1600 0 1677 1704 2278 2301 1990
3 800 800 800 1793 1736 2336 2227 2023
4 800 800 0 1833 1831 2310 2341 2079
5 800 200 800 1659 1595 2178 2227 1915
6 800 200 0 1687 1918 2325 2330 2065
7 400 1600 800 1721 1746 2312 2246 2006
8 400 1600 0 1816 1875 2359 2248 2074
9 400 800 800 1692 1858 2258 2209 2004
10 400 800 0 1724 1806 2298 2159 1997
11 400 200 800 1703 1556 2202 2161 1906
12 400 200 0 1706 1775 2273 2185 1985
13 0 1600 800 1774 1628 2343 2157 1976
14 0 1600 0 1762 1707 2357 2255 2020
15 0 800 800 1761 1531 2305 2182 1945
16 0 800 0 1666 1591 2189 2214 1915
17 0 200 800 1694 1715 2248 2299 1989
18 0 200 0 1693 1737 2183 2146 1940
Table 5. Grade index by years.
Pounds per Acre
applied to soil Year
Treatment K20 CaO MgO 1959 1960 1961 1962 Average
1 800 1600 800 .797 .729 .748 .744 .754
2 800 1600 0 .772 .749 .740 .755 .754
3 800 800 800 .768 .743 .716 .743 .742
4 800 800 0 .777 .789 .737 .736 .760
5 800 200 800 .808 .767 .672 .751 .750
6 800 200 0 .773 .809 .767 .782 .783
7 400 1600 800 .801 .796 .737 .755 .772
8 400 1600 0 .811 .769 .724 .743 .762
9 400 800 800 .830 .737 .718 .739 .756
10 400 800 0 .759 .784 .719 .751 .753
11 400 200 800 .813 .759 .684 .715 .743
12 400 200 0 .759 .797 .751 .761 .767
13 0 1600 800 .795 .761 .695 .726 .744
14 0 1600 0 .825 .764 .711 .716 .754
15 0 800 800 .813 .740 .697 .705 .739
16 0 800 0 .792 .715 .720 .716 .736
17 0 200 800 .820 .715 .724 .700 .740
18 0 200 0 .806 .794 .724 .726 .762
Table 6. Crop index by years.
Pounds per Acre
applied to soil Year
Treatment K20 CaO MgO 1959 1960 1961 1962 Average
800 1600 800
800 1600 0
800 800 800
800 800 0
800 200 800
800 200 0
400 1600 800
400 1600 0
400 800 800
400 800 0
400 200 800
400 200 0
0 1600 800
0 1600 0
0 800 800
0 800 0
0 200 800
0 200 0
1398 1296 1765 1751
1296 1278 1685 1738
1376 1290 1676 1654
1424 1445 1705 1724
1340 1224 1462 1671
1306 1551 1784 1822
1379 1391 1701 1697
1474 1441 1708 1670
1405 1367 1624 1634
1327 1416 1656 1622
1386 1185 1511 1553
1296 1415 1711 1665
1411 1238 1629 1568
1454 1303 1676 1615
1432 1123 1609 1541
1324 1195 1577 1584
1392 1223 1634 1610
1369 1383 1580 1559
1552
1499
1499
1574
1424
1616
1542
1573
1508
1505
1409
1522
1462
1512
1426
1420
1465
1473
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