LaMotte STH Outfit User Manual

SOIL TEX TURE UNIT

LMott

CODE 1067

QUAN TITY CON TENTS CODE

60 mL Soil Flocculating Reagent 5643PS-H
60 mL *Texture Dispersing Reagent *5644PS-H
1 Soil Texture Stand 1053
3 Test Tubes, Soil Texture, 50 mL, w/caps 0760
2 Pipets, 1 mL, plastic, w/caps 0372
1 A Study of Soil Science Handbook 1530

*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 accompanying MSDS before using.

To order individual reagents or test kit components, use the specified code
number.

This test is designed to separate soil into its three basic mineral fractions:
sand, silt, and clay. The amount of time required for the soil particles of
various sizes to settle in the soil separation tubes forms the basis for this
test. From the amount of material collected in each tube it is possible to
determine the approximate percentage of each fraction as represented in
the original soil sample.

The procedure for preparation of the soil sample for testing is described in
the accompanying handbook, A Study Of Soil Science.

The separation tubes should be marked for identification in the following
manner: Mark the first sedimentation tube “A”, the second “B”, and the
third “C”.

PRO CE DURE

1. Place the three Soil Separation Tubes in the rack.

2. Add the soil sample to Soil Separation Tube “A” until it is even with

line 15.
NOTE: Gently tap the bottom of the tube on a firm surface to pack

the soil and eliminate air spaces.

3. Use the pipet (0372) to add 1 mL of *Texture Dispersing Reagent
(5644PS) to the sample in Soil Separation Tube “A”. Dilute to line
45 with tap water.

4. Cap and gently shake for two minutes, making sure the soil sample
and water are thoroughly mixed.

The sample is now ready for separation. The separation is accomplished by
allowing a predetermined time for each fraction to settle out of the
solution. Be sure that you continue to gently shake the separation tube up
to the time of the first separation (Step 5).

5. Place Soil Separation Tube “A” in the rack. Allow to stand
undisturbed for exactly 30 seconds.

6. Carefully pour off all the solution into Soil Separation Tube “B”.
Return Tube “A” to the rack. Allow Tube “B” to stand undisturbed for
30 minutes.

7. Carefully pour off the solution from Soil Separation Tube “B” into
Soil Separation Tube “C”. Return Tube “B” to the rack.

8. Add 1 mL of Soil Flocculation Reagent (5643PS) to Soil Separation
Tube “C”. Cap and gently shake for one minute.

9. Place the Soil Separation Tube “C” in the rack and allow to stand
until all the clay in suspension settles. This may require up to 24
hours.

NOTE: Unless there is further use of the clay sample for air drying and study
as described later, it is not necessary to wait for the suspension to settle.

Due to the colloidal nature of clay in solution and its tendency to swell
and form a gel, the portion of clay remaining in Tube “C” is not used to
determine the clay fraction present in the soil. The clay fraction is
calculated by adding the sand and silt fractions and subtracting this total
from the initial volume of soil used for the separation.

EXAMPLE:

Tube “A” Sand 2 Initial Volume 15
+Tube “B” Silt +8 Total “A” & “B” -10
Total “A” & “B” 10 Clay 5

10. Read Soil Separation Tube “A” at top of soil level. To calculate
percentage sand in the soil, divide reading by 15. Multiply by 100.
Record as % sand.

11. Read Soil Separation Tube “B” at top of soil level. To calculate
percentage silt in the soil, divide reading by 15. Multiply by 100.
Record as % silt.