Organic matter determination test for soil in detail.

Organic matter determination test 

This test is performed according to ASTM D 2974

Objective

To determine the organic content of soils

Need and Scope

Organic matter influences many of the physical, chemical, and biological properties of soils. 

Some of the properties influenced by organic matter include soil structure, soil compressibility, and shear strength. 

In addition, it also affects the water holding capacity, nutrient contributions, biological activity, and water and air infiltration rates.

The decomposition of organic matter in the soil with time leads to excessive settlement of soil

Apparatus

1. Muffle furnace
2. Weighing balance
3. Porcelain dish
4. Spatula
5. Tongs

Procedure as per ASTM D 2974

Determine and record the mass of an empty, clean, and dry porcelain dish (M_p).

Place a part of or the entire oven-dried test specimen from the moisture content experiment in the porcelain dish and determine and record the mass of the dish and soil specimen (M_PDS).

Place the dish in a muffle furnace. Gradually increase the temperature in the furnace to 440 degrees.

Leave the specimen in the furnace overnight.

Remove carefully the porcelain dish using the tongs and allow it to cool to room temperature.

Determine and record the mass of the dish containing the ash (burned soil) (M_PA). Empty the dish and clean it

Calculations 

Determine the mass of the oven-dry soil.

M_D= M_PDS-MP

Determine the mass of the ashed (burned) soil.

M_A= M_PA-MP

Determine the mass of organic matter

M_O= M_D-MA

Determine the organic matter (content).

OM (%) = (M_O/M_D)*100