Percent Organic Matter Test

The dried soil sample from the soil moisture test was used in this test. The soil, 63.0g, was put in a crucible and above a Bunsen burner for 30 minutes. By doing this, the organic matter in the soil is converted to carbon dioxide and water. The difference in soil mass before and after Bunsen burner heating will determine the mass of organic matter.

 

When the crucible was taken off the burner and allowed to cool, the mass of the soil was recorded again (45.7g). By just measuring the mass of the sample after heating, only the remaining soil mass is determined. To find the organic matter is to find the loss of mass before and after heating. This was calculated as follows:

63.0g (before) - 45.7g (after) = 17.3g (organic)

17.3g (organic) / 63.0g (total) = 27.4% organic matter.

17.3g or 27.4% of the soil sample was organic matter.


Organic matter in soil is one of the most important factors of the substance. Organic matter is the main source of nutrients in soil, holds water within the soil to prevent leaching, and contributes to clumping, which prevents erosion.