LaMotte SOIL PHOSPHORUS DEMONSTRA TION TEST KIT - Manual (Page 2)

IN TRO DUC TION
The importance of phosphorus to plant life has been outlined in the
accompanying handbook, A Study of Soil Science. In this exercise the
student will:
A. Study the color reaction of High Fertility Soil (5724) which contains
a high phosphorus content.
B. Test a soil sample of unknown value to determine if phosphorus is
present and if so, determine the relative level of phosphorus that is
present in the soil sample. The soil samples used may be furnished by
the instructor or collected and prepared by the student.
PRO CE DURE
1. Fill a graduated test tube (0755) to line 6 with *Phosphorus
Extracting Solution (5704).
2. Use 0.5g spoon (0698) to add two measures of the soil sample to the
test tube. Cap and gently shake for one minute.
3. Without removing the cap, allow the tube to stand undisturbed until
the soil particles settle, leaving a clear liquid layer above the soil.
4. Use the pipet (0364) to fill a second test tube to line 3 with the clear
extract. To accomplish this, squeeze the bulb of the pipet before
inserting into the test tube containing the soil and extracting
solution. This prevents agitation of the clear extract. After inserting
release the pressure on the bulb and “draw-up” a portion of the clear
extract. Continue to transfer clear extract in this manner until the
level of solution is even with line 3 of the second tube.
5. Add 6 drops of the *Phosphorus Indicator Reagent (5705) to second
test tube. Cap and shake to mix.
6. Add one *Phosphorus Tablet (5706). Cap and shake until tablet
disintegrates.
7. What color appeared? Match color of the reaction to the colors
printed on the Soil Phosphorus Color Chart (1372). Is the
phosphorus level High? Medium? or Low? Record the result on a Soil
Analysis Report Form (1582).
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