LaMotte Greenhouse Soil Testing Outfit GS-01 - Manual (Page 6)

PRE PARING THE SOIL EX TRACT
A single soil extract is used for all the tests. Between 17 and 18 mL of
soil extract are needed to complete the series of tests. Because of the
variable nature of greenhouse mixes, it is not always possible to obtain
the required amount of extract from a single extraction. Therefore, it is
recommended that the operator carry out the extraction in duplicate
unitl it has been determined that a single extraction will provide a
sufficient amount of extract.
NOTE: The Demineralizer Bottle (1115) will be the source of all
deionized water for these procedures. Read the Demineralizer Bottle
Instructions before proceeding.
1.
Remove plunger from 60 mL syringe (0943).
2. Place filter paper on disc (0947) in the barrel of syringe, centering it
over the discharge hole. Moisten paper with a few drops of deionized
water.
3. Cover the discharge tip of the syringe with a black rubber bulb.
4. Fill the syringe to within 1a” of the top with well mixed,
unscreened soil sample.
5. Use the Demineralizer Bottle (1155) to add deionized water to the
soil. Continue adding deionized water a little at a time until the soil
is saturated, and a v” layer of water is standing on top of the soil.
6. Place the syringe in foam stand. Wait at least 2 hours for the
extraction to occur.
7. Place the syringe in the Extraction Stand (1110). Remove the black
rubber bulb from the tip of the syringe.
8. Place a plastic beaker (0944) under the syringe top. Insert the
plunger, and exerting pressure on the plunger, force the water
through the soil, into the beaker. The extract is now ready to be
used in the tests.
AL TER NA TIVE LAB O RA TORY PRO CE DURE
If laboratory facilities are available, the following procedure may be used
to obtain the soil extract.
1.
Measure 150 to 250 mL of well mixed, but not screened, soil.
2. Wet soil until saturated. Mix to form a paste. Let sit for at least 2
hours.
3. Place soil on a piece of dry filter paper in a Buchner funnel. Apply
suction until 10 to 20 mL of extract is collected.
6
PO TAS SIUM
QUANTITY CONTENTS CODE
50 *Potassium Reagent B Tablets *5161-
H
250 mL *Potassium Reagent C *5162-K
1 Pipet, plastic, transfer 0364
3 Test Tubes, Potash “A” 0245
2 Test Tubes, Potassium, glass 0232
1 Potassium Reading Stand 0946
*WARNING: Reagents marked with a * are considered hazardous substances.
Material Safety Data Sheets (MSDS) are supplied for these reagents. For your
safety, read label and acoompanying MSDS before proceeding.
PRO CE DURE
1.
Use a 1 mL pipet (0364) to add 1 mL of soil extract to the Potash
“A” tube (0245). Dilute to line with deionized water.
2. Add one *Potassium Reagent B Tablet (5161). Cap and mix until
tablet disintegrates.
NOTE:
The temperature of Potassium Reagent C and the sample
must be kept between 20 - 27° C (68 - 80° F). On warm days, the
Potassium Reagent C and test tube containing Potassium Reagent B
may be cooled by placing them in cold water before mixing.
3. Slowly fill test tube to upper line with *Potassium Reagent C
(5162), allowing Potassium Reagent C to run down the side of the
tube. Swirl to mix. A precipitate will form if potassium is present.
4. Place an unmarked Potassium Tube (0232) in the clip of the
Potassium Reading Stand (0946).
5. Use the pipet (0364) to add the reacted sample slowly, allowing it to
run down the side of the tube. Looking down through the tube,
slowly add reacted sample until the black line on the Potassium
Reading Stand just disappears.
6. With the bottom of the tube resting on the plate, compare the
sample level to the scale. Read result from scale.
7. Multiply reading by 3. Record as ppm Potassium.
NOTE:
The test result is multiplied by 3 because the original
dilution was 1:3. If a different dilution factor is used, multiply by the
appropriate factor.
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