How to build soil organic matter


  • Matt Ruark
  • UW-Madison Soil Science Department
Project Media

One of the simplest and most comprehensive measurements of soil health is soil
organic matter (SOM). Soil organic matter is connected to the ability of the soil to
provide nutrients, retain water, and improve yields. As farmers seek to increase the
SOM in their fields, it is important to reflect on the management practices that will
lead to increases in SOM, the long-term nature of the gain in SOM, and inherent soil
factors that dictate the ability of farmers to increase (or decrease) their SOM rapidly.
Soil OM is measured as loss on ignition, which requires burning the soil and
measuring what remains. Soil OM is typically about 50% carbon. Most scientific
studies measure and report SOM in terms of soil organic carbon (SOC). The SOC
can be multiplied by two to estimate SOM percentage.