Group Title: Mimeo report - North Florida Experiment Station ; 68-7
Title: Seasonal variation of soil analysis in shade tobacco plots
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00066045/00001
 Material Information
Title: Seasonal variation of soil analysis in shade tobacco plots
Series Title: NFES mimeo rpt.
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
North Florida Experiment Station
Publisher: North Florida Experiment Station
Place of Publication: Quincy Fla
Publication Date: 1968
 Subjects
Subject: Soils -- Nutrition   ( lcsh )
Tobacco -- Effect of chemicals on   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: F.M. Rhoads.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00066045
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 69860250

Full Text

( UF U-7 Quincy, Florida LIr RARY
January 31, 1968 IE LIBRAR

NFES Mimeo Report 68-7 APR
APR "8 l3
SEASONAL VARIATION OF SOIL ANALYSIS IN SHADE TOBACCO PLOTS

F. ERoads/ r S. Univ. of Eloric


INTRODUCTION

Soil samples are usually collected for routine analysis during the widter in order to
plan the fertilizer program for the following crop season. This is the logical procedure
to follow because of the time involved in getting the soil analysis report returned to the
grower and if lime is needed it can be applied during the slack season. A moredefficient
job of fertilization would be possible if soil samples were collected and analyzed A few
days prior to applying fertilizer. Since this is impractical it is desirable to havd
information regarding seasonal changes in the nutrient status of the soil. This type of
information would enable allowances to be made in fertilizer recommendations to take care
of anticipated changes and more nearly insure a proper plant nutrient balance during the
growing season. The purpose of this report is to present data showing seasonal variation
in plant nutrient content of the soil.

METHODS

Soil samples collected at different times during the year were analyzed for pH, P205,
K20, CaO, and MgO. Crop years included were 1959, 1960, 1961, 1962, 1964, 1965, and 1966.
Samples were taken at each date from 3 separate experimental shade tobacco plots which were
fertilized alike for that particular year. The data reported are averages of the 3 plots.
Top soil texture was loamy fine sand (medium light), therefore, heavier soils would be
expected to have less seasonal variation of plant nutrient content and lighter soils would
probably have greater variation. Plots from 1959 through 1962 received the following
amounts of fertilizer materials per acre: 1600 pounds of 41% cottonseed meal, 600 pounds of
tungnut meal, 300 pounds ammonium nitrate, 200 pounds of treble superphosphate and 300 pounds
of sulfate of potash. This was a 7-3-5 analysis applied at the rate of 3000 pounds per acre.
About two-thirds of the fertilizer was applied 4 to 5 weeks before transplanting and the
remainder 2 to 3 weeks after. Plots were fertilized with 2500 pounds per acre of an 8-5-7
mix prepared from similar materials during the period 1964 through 1966. A two year
rotation was practiced in both periods. Lime was not applied from 1959 to 1962 but the
plots had received lime prior to this time. About one-half ton of lime per acre was
applied to the 1965 crop and one ton per acre to the 1966 crop.

RESULTS

As shown in table 1 soil pH values are lower in May and June and higher in January,
February, and March. Variations of 0.5 to 1.0 pH unit occurred every year shown in the
table. Since May and June are months of most rapid growth for tobacco and most other warm
season crops, the low point of soil pH occurs during the crop growing season and it is
always higher when soil samples are collected from the field. Therefore, about 0.5 should
be subtracted from the pH of a soil samples to give the expected soil pH during the growing
season. For example, if the pH is 6.2 in a soil sample taken during the winter months the
soil pH in the represented field during the growing season should be approximately 5.7.


1/
Assistant Soils Chemist, North Florida Experiment Station, Quincy, Florida.










Table 2 shows the seasonal variation of soil phosphorus which is expressed as pounds
per acre of P205 extracted from the soil sample. Extractable soil P205 does not change very
much'seasonally as is indicated in the table. Research has shown that phosphorus is
immobilized or fixed in the soil, therefore, there is very little relationship between
exctractable:soiF phosphorus and the amount added in fertilizer. However, continued use of
fertilizer containing high amounts of P205 will gradually build up the extractable phosphorus
in the soil.

The amount of potassium (or potash) in the soil is expressed as pounds per acre of K20
extracted from the sample. Soil K20 varies quite noticeably with the seasons and rainfall.
Most soils in this area do not fix potassium, therefore, potassium added in fertilizer will
increase the amount of extractable K20 proportionately. Fertilizer was applied April 8,
1960; February 22, 1961; February 24, 1962; March 30, 1964; April 7, 1965; and March 23,
1966 and table 3 shows an increase in extractable K20 in soil samples taken soon after these
dates. Heavy rains will leach some potassium, however, it is difficult to say how much is
lost annually by this process. Shade tobacco removes 80 to 110 pounds of K20 per acre
annually in the leaves and the stalks contain several pounds per acre. The low soil
potassium levels in July are brought about by the high potassium uptake of shade tobacco
plants and to some extent leaching by heavy rains. After the stalks are plowed under in the
fall soil potassium builds back up some due to the element being leached out of the dead
stalks.

Soil calcium is expressed as pounds per acre of CaO. Data shown in table 4 indicates
that soil calcium level is not affected very much seasonally. Additions of calcium as
limestone will give an increase in extractable CaO of about 200 to 400 pounds per acre for
1000 pounds of high calcic lime and about 400 to 700 pounds per acre for 2000 pounds of high
calcic lime per acre. The amount of CaO in the soil sampe extract is not always a good
indication of what the soil pH will be. This is shown quite clearly by comparing the
sampling dates in May, 1965 and May, 1966 in tables 1 and 4. In 1966 soil calcium was
higher than in 1965 yet soil pH was lower in 1966. This indicates that pH is affected by
factors other than calcium level of the soil.

There is quite a lot of variation in magnesium level between sampling dates shown in
table 5, however, in general soil MgO level does not change very much with seasons.

Monthly rainfall is shown in table 5 for the years soil sample data were collected for
this report. Soil potash level appears to be affected more by rainfall than any of the
other nutrients included in the analysis. In 1964 a 9 inch rain occurred on December 4 and
the potassium level dropped from 479 pounds K20 per acre in November, 1964 to 246 pounds in
March, 1965.

At the present time it appears that for best tobacco quality and highest crop value a
soil analysis at mid-growing season should show: pH of about 6.0, P205 50 to 80 pounds per
acre, K20 600 pounds per acre, CaO 1000 pounds per acre, and MgO 250 pounds per acre.






FMR
2/15/68
350 CC









-3-

Table 1. Seasonal variation of pH in 1:1 volume soil-water suspension.

Crop Month
Year Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug.

1959 5.8 5.6 6.0 6.2 6.5 5.5 5.2 5.4 -
1960 5.7 5.6 5.5 5.5 5.5 5.4 4.9 5.2 5.5
1961 5.4 5.2 5.3 5,5 5.9 5.4 5.6 5.8 -
1962 5.8 6.0 5.9 5,8 5.9 5.3 5.6 6.0
1964 6.3 I 548 5.6 5.3 5.4
1965 5.5 6.0 5.8 5.8 .9
1966 6.3 5,8 9,6 5.8 5.8




Table 2. Seasonal variation of P205 in soil extract-pounds per acre

Crop Month
Year Nov. Dec. Jan.. Feb. Mar. Apti May June July Aug.

1959 39 52 43 37 50 47 53 39
1960 30 26 28 31 31 49 50 33 30
1961 25 26 21 28 28 33 29 34 -
1962 27 22 25 36 37 54 34 36 -
1964 51 40 56 56 48 -
1965 52 57 73 98 100 -
1966 69 61 74 86 51 -




Table 3. Seasonal variation of R20 in soil extract-pounds per acre.

Crop Month
Year Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug.

1959 906 1020 700 535 577 590 629 186 -
1960 358 344 308 237 360 612 371 175 232
1961 385 334 300 337 444 425 294 200 -
1962 479 453 346 514 486 511 284 290 -
1964 404 465 410 306 186 -
1965 479 246 409 245 211
1966 208 422 595 285 211 -











Table 4. Seasonal variation of CaO in soil extract-pounds per acre.

Crop Month
Year Nov. Dec. 'Jan. Feb. Mar. Apr. May June July Aug.

1959 1175 1120 835 839 718 760 792 788 -
1960 690 616 658 593 714 774 779 737 746
1961 805 769 769 609 719 825 672 639 -
1962 701 658 695 516 486 675 667 649 -
1964 696 678 601 657 644 -
1965 546 1143 724 812 701 -
1966 1162 1052 985 928 1047 -




Table 5. Seasonal variation-of MgO in soil extract-pounds per acre.

Crop
Year Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug.

1959 286 328 315 261 236 264 294 260 -
1960 256 217 228 195 200 217 222 192 312
1961 227 283 89 182 90 103 56 153 -
1962 259 184 212 235 135 238 199 168 -
1964 251 185 230 255 198 -
1965 193 276 317 256 243 -
1966 387 370 352 310 353 -




Table 6. Monthly rainfall recorded at the North Florida Experiment Station-inches.

Crop
Year Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

1958 4.32 3.95 5.06 8.94 7.39 6.21 3.20 4.14 1.07 2.53 4.44 1.57
1959 5.84 6.63 9.86 2.92 6.86 6.70 5.78 2.89 4.37 9.72 0.22 3.09
1960 3.89 7.65 3.33 6.89 3.78 5.99 7.66 5.35 13.51 2.36 0.24 2.11
1961 3.49 5.36 5.43 5.21 2.21 5.59 7.51 14.31 1.90 0.00 2.10 4.02
1962 2.72 3.07 6.03 3.96 0.55 4.85 4.15 3.10 3.87 1.63 6.08 3.07
1963 6.07 4.54 1.87 1.56 8.23 5.45 7.23 3.12 5.12 0.15 3.20 5.41
1964 8.06 7.93 5.25 4.89 1.74 6.63 10.87 5.78 6.04 10.25 2.38 13.79
1965 4.49 9.88 8.58 9.41 0.04 13.83 5.76 7.07 4.64 2.44 2.48 4.31
1966 9.38 8.38 3.68 0.88 5.41 5.37 6.56 7.78 9.36 3.08 1.56 2.97




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