LaMotte STH Outfit - Manual (Page 11)

11
Humus
Humus consists of the complex remains of fresh plant and animal residue
after extensive chemical and biological breakdown. Humus accounts for
60% to 70% of the total organic carbon in soils. It can modify the physical
properties of a soil, strongly affecting its chemical and biological properties.
PROCEDURE
1. Use the 0.5 g spoon (0698) to add eight level measures of soil to
a soil extraction tube (0704).
2. Use the Demineralizer Bottle (1155) to fi ll the tube to the 14 mL
line with demineralized water. Cap and shake to mix.
3. Use a 0.5 g spoon (0698) to add two level measures of *Humus
Screening Reagent Powder (5119). If necessary, add more
demineralized water to return the level of the liquid to the 14 mL
line. Cap and shake vigorously for one minute.
4. Add 15 drops of Soil Flocculating Reagent (5643). Cap and mix
gently. Allow to settle for several minutes.
5. Use a piece of fi lter paper (0465) and a plastic funnel (0459) to fi lter
the mixture into a second extraction tube. (Fold fi lter paper in half
and then in half again to form a cone which is fi tted into the funnel.)
6. Compare the clear fi ltrate in the second extraction tube with the
Humus Color Chart (1384).
Interpretation
The Humus color comparator is labeled with values of 1, 2, 3, 4, and 5.
The results are interpreted as follows:
Humus or Organic Matter in Soil
Humus Reading 1 2 3 4 5
Agricultural Soils Low Medium High
Garden
Greenhouse Soils Low Medium High
Organic Soils Low Medium High