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Group Title: Mimeo report - University of Florida Everglades Experiment Station ; 55- 6
Title: Rapid laboratory methods for the analysis of soil and plant tissue samples
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067589/00001
 Material Information
Title: Rapid laboratory methods for the analysis of soil and plant tissue samples
Series Title: Everglades Station Mimeo Report
Physical Description: 13 leaves : ; 29 cm.
Language: English
Creator: Forsee, W. T
Ozaki, C. T ( Charles T )
Everglades Experiment Station
Publisher: Everglades Experiment Station
Place of Publication: Belle Glade Fla
Publication Date: 1954
 Subjects
Subject: Soils -- Analysis -- Florida   ( lcsh )
Plant tissue culture -- Florida   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: W.T. Forsee, Jr. and Charles T. Ozaki.
General Note: "October 12, 1954."
 Record Information
Bibliographic ID: UF00067589
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 65519226

Table of Contents
    Front Cover
        Front Cover
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
Full Text
AiD3 ,ir


RAPID LABORATORY METHODS FOR THE ANALYSIS OF
SOIL AND PLANT TISSUE SAMPLES


by


W. T. Forsee, Jr. and Charles T, Ozaki


The procedures listed on the following pages
are some of the methods of soil and plant anal-
ysis used in the Chemistry and Soils Division
of the Everglades Experiment Station.



Everglades Station Mimeo Report 55-6

Belle Glade, Florida


October 12, 1954


.iO 2o ^ 102














RAPID LABORATORY METHODS FOR THE ANALYSIS OF
SOIL AND PLANT TISSUE SAMPLES


W. T. Forsee, Jr. and Charles T. Ozaki*



Most of the methods described on the following pages are adaptations of
methods found in the literature that have been modified to suit local conditions.
The methods for determination of the bases which involve acid extraction are not
suitable for soils containing more than traces of alkaline salts. The water ex-
traction procedure described for phosphorus should not be used on soils with high
pH values. Under such conditions a carbonic acid extraction should perhaps be
followed. The plant tissue tests described are closely associated with the soil
testing procedures in that the final dilutions and aliquots are prepared in such
a way as to fit into the scheme for soil testing using the same standard solu-
tions for comparison of colors and flame intensities.

All these procedures have evolved during a number of years of use in
these laboratories for analyses associated with research on fertilizer require-
ments of crops and plant nutrition studies, and in the operation of a limited
soil testing program on a service basis for commercial growers in the South Flor-
ida area.


PREPARATION OF "OIL SAMPLES FOR TESTING

Soil samples to be tested should be placed on clean trays in the soil
preparation room and air dried. As soon as the samples are sufficiently dry
they should be put through the standard 2 mm. sieve. For mucks especially it is
best to sieve the sample before it is completely air dry because the lumps of plas-
tic material will break up much easier when handled at a moisture level between
field moist and air dry. Peat samples should not be stored more than 6 to 8 weeks
after drying before analysis because of the shrinkage and change in volume which
takes place. Peat or muck samples to be analyzed for nitrogen should not be air
'dried. Such samples should be brought to the laboratory and analyzed immediately
after they are taken. They may be run throuTh the 2 mm. sieve if they are suffi-
ciently dry in their field moist condition.







*Chemist in Charge and Assistant Chemist, respectively, Florida Everglades
Experiment Station, Belle Glade.










-2-


TESTING SOILS FOR pH

Measure out into a glass tumbler 50 ml. of sieved air dry soil. For
sands add an equal measure of distilled water and for peats and mucks 2 measures
of distilled water. Allow to stand about 2 hours with intermittent stirring.
Measure the pH by means of a glass electrode stirring each sample just prior to
immersing the electrode.


TESTING SOILS FOR MOISTURE EQUIVALENT

Measure out in duplicate approximately 8 teaspoons (32 ml.) of homo-
genized soil into the centrifuge moisture boxes. The absolute amount of soil
is not important but the duplicate samples must be the same amounts so they
will balance in the centrifuge. Soak the samples in water over-night. Place
in centrifuge head, duplicate samples opposite each other, and centrifuge for
30 minutes at a controlled speed of 2440 rpm. Transfer the soil to a moisture
can, weith, dry 24 hours in oven at 1050 C and weigh again.

% M.E. = loss in wt. x 100
dry wt. sample


TESTING SOILS FOR CALCIUM, MAGNESIUM,
POTASSIUM, SODIUM, AND MANGANESE

Extracting Solution
Prepare a 0.5 N acetic acid solution by diluting 540 ml. glacial
acetic to 19,000 ml.

Extraction Procedure
Measure out 2 level teaspoons (10 ml.) of air dry sieved soil into
a 25x200 mm. screw cap tube. Add 50 ml. of the 0.5 N acetic acid extracting
solution, mix and allow to stand over-night. Place the rack with the tubes
containing the measured samples and the extracting solution on the shaking
machine and shake for 60 minutes. Allow to settle and decant the supernatant
liquid onto a S & S No. 576 filter paper. Pour back the first few ml. that
come through in order to obtain a clear filtrate. Use this filtrate for de-
terminations of the bases on the Beckman Flame Photometer.

A 1 level teaspoon measure of air-dry soil that has been passed
through a 2 mm. sieve is equivalent to approximately 1/150,000,000 acres. This
value was used in preparing the standards for calibration of the tests.










-3-


Flame Photometer Adjustments


Turn switch on spectrophotometer to check position and allow instru-
ment to warm up 30-40 minutes before using. Turn on oxygen pressure and then
hydrogen. Light burner and then adjust oxygen pressure to 15 pounds per square
inch, and hydrogen to t pounds per square inch after lighting burner.

A. Potassium Determination
Wave length--7686
Red sensitive phototube (Lever in)
Switch = 0.1 Position of Resistor Box = IO0


1. For 0 to 100 lbs, per
Slit width = 0.1
Readings at different
100 Ibs./A = 100%
50 lbs./A = 57-58%

2. For 0 to 300 Ibs. per
Slit width = 0.06
Readings at different
300 Ibs./A = 100%
100 Ibs./A = 45%


acre range,

concentrations.


acre range

concentrations


B, Calcium Determination
Wave length--422 j
Blue Sensitive Phototube (lever out)
Switch = 0.1 Position of Resistor Box = 2.0
Photo-multiplier = 4.0.

1. For 0 to 1000 lbs. per acre range
Slit width = 0.02
Readings at different concentrations
1000 lbs./A = 100%
500 Ibs./A = 53%

2. For 0 to 5000 Ibs. per acre
Slit width = 0.01
Readings at different concentrations
5000 lbs./A = 100%
1000 Ibs./A = 28%

C. Magnesium Determination
Wave length--370 +
Blue Sensitive Phototube (lever out)
Switch = 0.1 Position of Resistor Box = 2.0
Photomultiplier = 6.0.


1. For 0 to 100 ppm,
Slit width = 0.08
Readings at different concentrations
100 ppm = 100%
50 ppm = 65-66%


3. For 0 to 250 Ibs./A
Slit width = 0.12
Readings at different concentra-
tions
250 lbs./A = 100%
100 lbs./A = 55%









2. For 0 to 250 ppm
Slit width = 0.0O
Readings at different concentrations
250 ppm = 100%
100 ppm = 49%

D. Sodium Determination
Wave length 588 -+
Blue Sensitive Phototube (lever out)
Switch = 0.1 Position of Resistor Box = 2.0
Photomultiplier = 3.0

1. For 0 to 300 ppm
Slit width = 0.01
Readings at different concentrations
300 ppm = 100%
90 ppm = 57%

E. Manganese Determination
Wave length-W-03 t
Blue Sensitive Phototube (Lever out)
Switch = 0.1 Position of resistor Box = 2.0
Photomultiplier = 6.0.

1. For 0 to 100 ppm
Slit width = 0.06
Readings at different concentrations
100 ppm = 100%
50 ppm = 68%

The parts per million for any solution with reference to the standard
solutions may be converted to Ibs. per acre by dividing by the factor 0.302,


PREPARATION OF STANDARD SOLUTIONS

Standard Potassium Chloride Soln. (2,000 Ibs. K per acre)

1.1544 gm. KC1 diluted to 1000 ml. with 0.5 N acetic acid
10 ml. diluted to 200 ml. = 100 Ibs. K per AT = 30.2 ppm.
15 ml. diluted to 100 ml. = 300 Ibs. K per A. = 90.6 ppm.
Standard Calcium Acetate Soln. (5,000 Ibs. Ca per acre)

6.6375 gm. Ca (02H302)2.H20 diluted to 1000 ml. with 0.5 N acetic acid
20 ml. diluted to 100 ml. = 1000 lbs. Ca per A. = 302 ppm.

Standard Mamnesium Sulfate Soln. (1,000 Ibs. per acre)

3.664 gm. Mg S04.7H20 diluted to 1000 ml. with 0,5 N acetic acid.
25 ml. diluted to 100 ml. = 250 Ibs. Mg. per A. = 7,.5 ppm.

Standard Magnesium Soln. (1,000 ppm.)
1.000 gm. magnesium metal diluted to 1000 ml. with 0.5 N acetic acid.
25 ml. diluted to 100 ml. = 250 ppm. Mg.


-4-










Standard Manganese Sulfate Soln. (500 apm.)


'.7024 gm. MnSOLC-H20 diluted to 1000 ml. with 0.5 N acetic acid.
20 ml. diluted to 100 ml. = 100 ppm, Mn :,.
10 ml. diluted to 100 ml. = 50 ppm. Mn
Standard Sodium Chloride Soln. (600 ppm).

1.5248 gm. NaC1 diluted to 1000 ml. with 0.5 N acetic acid.
15 ml. diluted to 100 ml. = 90 ppm. Na in the solution = 300 Ibs.
Na per acre.



TESTING SOILS FOR PHOSPHORUS

Extraction Procedure
Measure out 1 levsl teaspoon (4 ml.) of air-dry sieved soil into a
25x200 mm. screw cap tube. Add 50 ml. of distilled water, mix and allow to
stand over-night. Place on the shaking machine and shake for 60 minutes.
Remove from shaker, and filter immediately through S.&S. No. 402 filter paper.
Collect filtrate until exactly 20 ml. has been obtained. Add 4 ml. of 0.3 N HC1
and about 1/8 teaspoon decolorizing charcoal (phosphate free) from tip of spa-
tula. Shake and filter after 3 to 5 minutes. Pour back the first few ml. of
filtrate in order that it may be clear. Use this filtrate for subsequent deter-
minations of phosphorus.

Phosphorus Standard

Dissolve 0.3495 gm. Na2HPO.12H20 in 6.25 N HC1 and dilute to exactly
100 ml When 4 ml. of this solution is diluted to 50O ml. with distilled water
a standard is obtained that represents 40 pounds P per acre when 10 ml. is used
in the phosphorus test outlined in the procedure below. This standard contains
2.42 ppm. P. Determinations equivalent to 2 to 40 pounds P per acre may be made
by diluting to 12 ml. with 0.05 N H01 aliquots of 0.5 to 10 ml. and carrying
through the procedure for phosphorus tests.

Molybdate Reagent
Dissolve 12 gm. ammonium molybdate in 260 ml. water. Add a mixture
of 225 ml. concentrated hydrochloric acid and 50 ml. water. Store in an amber
glass bottle. Make fresh every two months.

Stannous Chloride Stock Solution
Dissolve the contents of a 1 ounce bottle of stannous chloride,
SnCl2.2H20 in 67.5 ml. concentrated hydrochloric acid, Store in a small tightly
stoppered amber glass bottle.

Stannous Chloride Reagent
Add 1 ml, of stannous chloride stock solution and dilute to 250 ml.
with distilled water. Make up fresh daily.








-6-


Procedure for P Determinations
Pipet 12 ml. of soil extract into an 18 mm, tube. For soils whose
phosphorus level is above the range of the test, use a smaller aliquot and add
sufficient 0.05 N HC1 to bring the volume to 12 ml. Add 2 ml. of molybdate
reagent, and 1 ml, of stannous chloride reagent and mix immediately. Read the
resultin- blue color after 10 minutes in the Photelometer with a red filter.
These colors are usually stable for at least 20 minutes provided nitrate nitro-
gent in the sample is not excessively high. Where difficulty of fading is en-
countered make the readings within 5 to 10 minutes after adding the stannous
chloride. The P content of the soil in pounds per acre may be read from the
standard calibration curve.


TESTING SOILS FOR IRON AND ALUMINUM

Extraction
Use the same solution and procedure as for K, Ca, Mg, Mn and Na.

Test for Iron
Standard iron solution--Dissolve 0.1316 gm. FeSOV(MH0)2SO0.6H20 in
about 200 ml. of 0,5 N acetic acid extracting solution in a 250 ml. volumetric
flask, add 10 ml. of 7 percent hydroxylamine hydrochloride solution and dilute
to 250 ml. with the extracting solution. Dilute as needed 10 ml. of this solu-
tion to 100 ml, with the extracting solution. The diluted solution is equiva-
lent to 25 Ibs. per acre Fe (7.5 ppm.).

Hydroxylamine hydrochloride--Dissolve 5 gm. of hydroxylamine hydro-
chloride in water and dilute to 100 ml.

o-phenanthroline--0.5 percent solution in 50 percent ethyl alcohol.

Procedure

To 1 ml. of the extract in a small glass vial, add one drop of hydro-
xylamine hydrochloride solution and mix. Add 2 drops of 6-phenanthroline solu-
tion and mix again. After 10 minutes compare with a series of standards con-
sisting of 0.1 ml. units of the standard solution ranging from 0 to 1 ml. When
stoppered and protected from light, the standards will keep for several months.
This same procedure may be used for plant tissue extracts.

Test for Aluminum

Standard aluminum solution--Dissolve 0.2523 gm. of A12(NH4)2(SO4)h.
24H20 in 100 ml. of the 0.5 N acetic acid extracting solution. Dilute as needed
10 ml. of this solution to 100 ml. with the extracting solution. The diluted
solution is equivalent to 50 Ibs. per acre (15 ppm. of Al).

Aluminon--Dissolve 0.20 gm of aluminon (Ammonium salt of aurintricar-
boxylic acid) in 100 ml. of water. Store in an amber glass dropping bottle and
prepare a fresh supply of the reagent every 6 months.

Starch solution--To 1 gm. of c.p. soluble starch add a few drops of
water and make a paste by stirring with a glass rod. Add slowly with stirring,
100 ml. of boiling distilled water. Filter while hot through S.&S. 576 filter
paper. Prepare fresh daily as needed.








-7 -


Hydroxylamine hydrochloride--Use 5 percent solution described under
iron test.

Procedure

To 1 ml. of the extract in a glass vial add 2 drops of the hydroxyla-
mine hydrochloride solution and mix. Add 3 ml. water and 1 ml. starch solution
and mix again. Add 2 drops aluminon reagent and mix thoroughly. Allow to stmd
for at least 30 minutes before comparing with a series of standards subjected
simultaneously to the same procedure.



TESTING SOILS FOR NITRATE NITROGEN
(Approximate Estimation)

Nitrate Nitrogen Reagent
Dissolve 0.05 gm. diphenylamine in 25 ml. concentrated sulfuric acid
at room temperature. Store in a glass stoppered amber colored bottle. This
solution should not be used if it is more than two weeks old.

Procedure for Test
Carefully measure out 1 teaspoon (4 ml.) of freshly sampled field moist
soil into an 18xlO1 mm. test tube. Add 10 ml. of the 0.5 N acetic acid extracting
solution and shake vigorously for 2 minutes. Filter throu-h S.&S. #576 filter
pqper. Carefully transfer 1 drop of soil extract to a white porcelain spot plate.
Add 5 drops of nitrate nitrogen reagent and stir with a thin glass rod. A blue
color indicates the presence of nitrate nitrogen. No perceptible blue color after
two minutes indicates less than 2 pounds nitrate nitrogen per acre. A pale blue
color indicates a very low nitrate nitrogen level. A strong blue color indicates
ample nitrogen for most crops. A heavy blue color indicates a very high nitrate
nitrogen.

This test is only an indication of the presence of low, medium or heavy
amounts of nitrate nitrogen. Such a test is usually sufficient for checking on
the advisability or necessity for nitrogen fertilization,cespecially on peat and
muck soils. When a more exact estimation is desired use the following procedure.


TESTING SOILS FOR NITRATE NITROGEN
(Quantitative Estimation)

Nitrate Nitrogen Standard Solution
Dissolve 0.3669 gm. of NaNO3 in distilled water and dilute to exactly
100 ml. A 5 ml. aliquot of this solution diluted to 100 ml. will give a standard
representing 100 pounds N per acre. Other s bandards may be prepared by an appro-
priate dilution.

Extracting Solution
Mix 5 ml. of 1 N copper sulfate and 25 ml. 0.4 percent silver sulfate.
Dilute this mixture to 12' ml. with distilled water.

Phenoldisulfonic acid
Prepared according to directions given in Colorimetric Methods of
Analysis, Vol. 1, page 633.








- 8 -


Ammonium Hydroxide 1-3
Prepared from 1 part concentrated ammonium hydroxide and 3 parts
distilled vater.

Procedure for Test

Measure out 1 level teaspoon (4 ml.) of freshly sampled soil into an
18 x 150 mm. test tube. If the field soil is not too moist, it should be put
through the 2 mm. sieve before sampling for analysis. Add 10 m%, of the extract-
ing solution and shake 1 minute. Add approximately 0.05 g. Ca(OH)2 and approx-
imately 0.10 g. MgC03, These amounts may be judged by volume from the tip of
a spatula. Shake 1 minute more. Filter on S,&S. #402 filter paper. Transfer
1 ml, of this soil extract to a test vial and evaporate to dryness. This is very
conveniently done with any number of samples by setting the vials in beakers and
placing in the drying oven at 105oC. Do not allow to remain in oven very long
after dryness is reached. Cool and add 0.25 ml. Phenoldisulfonic acid reagent
and rotate tube so the reagent comes in contact with all the residue. After 10
minutes add 2 ml. water and 5 ml. of the 1-3 ammonium hydroxide. After cooling,
read in the Photelometer using a blue filter and 1 cm. cells. A comparison of
this reading with the standard calibration curve will give the nitrate nitrogen
in pounds per acre six inch.



TESTING SOILS FOR AMMONIA NITROGEN

Ammonia Nitrogen Standard
Dissolve 0.284T gm. (NH4)2SO4 in about 50 ml. of the 0.5 N acetic acid
extracting solution. Dilute to exactly 100 ml. with this same solution. A 5 ml.
aliquot of this solution diluted to 100 ml, with the 0.5 N acetic acid will give
a solution standard representing 100 pounds N per acre.

Ammonia Nitrogen Reagent #1
Prepare apprxomately 1 N sodium hydroxide from C.P. NaOH and distilled
water.

Ammonia Nitrogen Reagent #2
Dissolve 50 gm. of sodium potassium tartrate in 100 ml. of distilled
water. Add 5 ml, Nessler reagent, shake and allow to stand over-night. Filter
and store in brown glass bottle.

Ammonia Nitrogen Reagent #3
Prepare a Nessler reagent from the ready prepared reagent chemical,
Paragon,

Procedure for Test

Extract the soil with 0.5 N acetic acid according to the directions
given for Nitrate Nitrogen (approximate estimation). Place 1 ml. of this extract
in one of the 18 mm. test tubes selected for colorimeter tubes. Add 5 drops of
Reagent #2, 8 drops of Reagent #1 and 5 ml. distilled water. Add 5 drops of
Reagent #3, shake and read in the Photelometor after about 5 minutes using a blue
filter. A comparison of this reading with the standard calibration curve will
give the ammonia nitrogen in lbs. N per acre six inches.





DETERMINATION OF ORGANIC MATTER
SANDY SOILS

Reagents
(I) Normal potassium dichromate solution--Dissolve 49.03 gm. dry
K2Cr207 in water to make exactly 1 liter.
(2) Concentrated sulfuric acid (not less than 96 percent).
(3) 85% phosphoric acid,
(4) Diphenylamine solution (0.5 percent in cone. H2SO0).
(5) Normal ferrous sulfate solution--Dissolve 556 gm. FeSO.*7H20
in water containing 30 ml. cone. sulfuric acid and dilute to 2 liters. This
reagent should be stored in a brown bottle under a thin film of white mineral
oil to prevent oxidation. A convenient arrangement is to provide a siphon from
this bottle to a burette equipped with a two-way stop cock.

Procedure

Approximately 10 to 15 gm of an air dry soil that has been put through
a 2 mm. sieve is placed in a mortar and pestled for about 2 minutes. This is done
in order to crush larger particles of organic matter which might be present. Weigh
out 5 gin. of this pestled soil into a 500 ml. Erlenmeyer flask. If the organic
matter content is estimated to be greater than 1.0 percent a proportionately
smaller sample should be used. A 2 gm. sample will give a convenient titration
for a soil whose organic matter content is 2 percent.

Exactly 10 ml. of normal potassium dichromate are added followed by
20 ml. of cone. H2SO, (not less than 96 percent). Shake the mixture for about
1 minute and let stand on an asbestos sheet for about 30 minutes. About 200 ml.
water are added, followed by approximately 10 ml. of 85% H3PO0 and 1 ml. of 0.5%
diphenylamine. Titrate with the normal ferrous sulfate solution until the mixture
ture turns to a purple or blue color, then titrate slowly until at the end point
the solution will flash to green. If more than 8 ml. of the potassium dichromate
are required to oxidize the organic matter, the determination should be repeated
using a smaller soil sample. A blank without soil present but otherwise like the
procedure used on the soil should be included with each group of tests. Walkley
(J. Agri. Science 25, 608 (1935) found mean recoveries of about 77 percent, making
necessary a correction factor of 1.3. Therefore, 1 ml. of normal dichromate sol-
ution is equivalent to 1.3 x 3.0 = 3.9 mgm. of carbon. To convert to organic
matter multiply by the conventional factor of 1.724. Thus, 1 ml. of normal di-
chromate is equivalent to 6.72 mg. of organic matter.

Calculation
The percent organic matter in the soil sample is calculated as follows:

(ml. ferrous sulf. for blank ml. for soil) x 10 x 6.72 x 100)
Ml. for blank x wt. sample in gms. x 1000









-10-


TESTING FRESH PLANT TISSUE FOR PHOSPHORUS,
POTASSIUM, CALCIUM AN)P MAGNESIUM


Sampling

The value of such tests depends to a certain extent upon the care ex-
ercised in sampling. Portions of the plant containing the largest percentage of
conducting tissue should be used in these tests. Samples should be selected from
portions of the plant that are in a vegetative condition indicating good growth,
but the use of very young tissue should be avoided. A sampling table now in use
for various vegetable crops is listed below:

Beans---lower portion of leaf petioles from leaves that are beyond
the very young tender stage but still in a staZe of rapid
growth.
Potatoes---lower portion of leaf petioles from leaves about 2/3
to 3/4 up the main stem measuring from soil surface.
Celery---lower portion of individual stalk from leaves in a good
vegetative stage.
Cabbage---portion of leaf rib near its junction with the main stalk;
strip off the leafy material with a razor blade. Select
those leaves that will ultimately become wrapper leaves.
Lettuce---same as cabbage.
Carrots---lower section of leaf petioles of leaves in a good vege-
tative state.
Corn and Sorghums---lower portion of stalks. Collect samples when
plants are 12 to 2h inches high and take the sample imme-
diately above the last node.

Samples should be collected in the morning and brought immediately to
the laboratory. Each sample should consist of several individuals. They should
never be allowed to stand uncovered in the sun or wind, Care should be exercised
to maintain the samples at as near their original moisture condition as possible
until analysis is begun. All samples should be washed in distilled water with
a soft brush and the excess water drained from their surface by placing them be-
tween clean paper towels.

Extracting Solution

Use the same 0.5 N acetic acid as used in soil tests.

Extraction Procedure

Arrange in parallel order all the stems of the composite sample on a clean
piece of plate glass. Slice off all the ends with a thin sharp blade and discard
this portion of the sample. Then slice off a cross section such that the total
weight of all the sliced pieces will weigh between 2 and 3 grams. After a little
practice it will be found that considerable skill has been obtained in being able
to slice off an approximate weight of plant material.









- 11 -


Weigh immediately to the nearest 0.01 gram. Place the weighed sample
in the container of a Waring Blendor, add 50 ml. of the extracting solution and run
on the Blendor for 2 to 4 minutes depending upon how difficult the plant tissue is
to macerate, Pour the mixture into a filter fitted with an S.&S. No. 605 paper,
pour back the first few ml. that come through and collect a portion of the filtrate
for use in testing for P, K, Ca, Mg, Mn, and Na. At the same time that the 2 to 3
gm. sample for analysis is weighed, a sample of approximately 10 gms. should be
weighed out to the nearest 0,01 gram for a dry matter determination. Place this
sample in a tared 30 ml. beaker and dry for about 48 hours at 90-95oC, From the
dry weight of this sample the oven dry weight of the sample used for analysis may
be determined and the results of all analyses reported on an oven dry weight basis.

In certain instances it may be necessary to remove all coloring matter
from the plant extract when determinations of phosphorus are to be made. In such
cases about 25 ml, of the filtrate is placed in a 125 ml. Erlenmeyer with 1/8 tea-
spoon of acid washed decolorizing charcoal, shaken intermittently for 10 minutes
and filtered through an S.&S. No. L02 filter.

Determination of Bases

Use the filtrate from the extractions described above for determination
of K, Ca, Mg, Mn, and Na with the flame photometer. Most elements except K may be
determined on the extracts without dilution. For K determination it is usually
necessary to dilute the extract 1 to 2 or 1 to 3 with 0.5 N acetic acid. The same
standard solutions and standard curves are used as for soil analyses. The readings
in pounds per acre multiplied by the factor 0.302 give the readings in terms of ppm.
in the plant tissue extract.

ppm. x 50 x 100 = % in tissue, oven dry basis.
1,000,000 x dry wt. sample

Phosphorus Determination

Transfer 1 ml. of the plant tissue extract to an 18 mm. selected test tube
and dilute to 10 ml. with distilled water. Any other size aliquot that will give a
color within the range of the test is exactly the same as that for determining phos-
phorus in soil extracts. Briefly, the test is as follows: Add 2 ml. of approxi-
mately 0.3 N hydrochloric, 2 ml. molybdate reagent, 1 ml. stannous chloride reagent,
mix and read after 10 minutes in the Photelometer with a red filter. The ppm. of P
in the 10 ml. of diluted aliquot may be read from the standard curve prepared for
soil tests. The readings in pounds per acre multiplied by the factor 0.0605 give
the readings in terms of ppm.

ppm. x 10 x 50 x 100 = % P in tissue,
1,000,000 x ml. aliquot dry wt. sample oven dry basis








- 12 -


ANALYSES OF PLANT ASH


Weigh out into a 100 ml. beaker 0.1 to 0.15 gm. of plant ash. Moisten
with water, cover with watch ;lass and add slowly 5 ml. 1-1 HC1. After evapora-
tion to dryness take up in 0.5 N acetic acid extracting solution and dilute to
200 ml. with this solution. Use 1 ml. for determination of P as described in the
procedure for plant tissue tests. Determine K, Ca, Mg, Mn, and Na on the flane
photometer after dilution.

ppm. x % ash x 0.002 = % P in dry plant tissue
wt. ash sample used

ppm x % ash x 0.0002 = % K, Ca, Mg,
wt. asn sample used x ailution required to make reading or Mn in dry
plant tissue


NITRATE TESTS ON FRESH PLANT TISSUE


Weight out in triplicate 2 g. samples of fresh chopped plant material
and extract in a Waring Blendor with 40 ml. of extracting solution described under
Testing Soils for Nitrate Nitrogen, page 5. Filter and treat a 10 ml. aliquot
with Ca(OH)2 and MgCO3 as described under Soil Tests. Continue as a soil extract
using less than 1 ml. aliquots for determination if the nitrates are beyond the
range of the test, when 1 ml. is used. Read in lbs. per acre from soil test stan-
dards. Weigh out a 10 g. sample for dry weight determination.

lbs. N per A. x 0.1208 = % N in dry tissue.
green wt. sample x % dry matter


ANALYSIS OF PLANT AND PEAT SOIL ASH


Weigh out into a 100 ml beaker 0.15 gns, of ash. Moisten with water,
cover with watch glass and add slowly 5 ml. 1-1 HC1. Evaporate to dryness, take
up in 0.5 N acetic acid and filter into a 200 ml. volumetric flask washing filter
paper several times with 0.5 N acetic. Transfer filter paper and contents to a plat-
inum dish, add a few ml. of water, several drops of H2S04 and 5 ml. hydrofluoric
acid. Evaporate an steam bath and ignite. Add a few drops of water and HF and
evaporate again. Take up in 0.5 N acetic and add to the first filtrate. Dilute
to volume. Use 1 ml. for determination of P. Determine K, Ca, Mg, Mn and Na on
flame photometer and Fe and Al colorimetrically,




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