Leco Analysis to Measure Soil Carbon

For some time now there has been a great deal of debate around soil carbon and what farming methods are proved to be the most effective when it comes to increasing the carbon levels of the soil. This has resulted in CWFS forming a project to find out which farming practice is best for storing soil carbon as well as how each farming practice is impacting soil health.


How will we do it: CWFS has set an experiment to demonstrate the effects of four separate farming systems. These farming systems are traditional cropping and grazing, reduced tillage cropping-grazing mixed, continuous cropping rotation and a perennial pasture system for all you sheep graziers out there.

  • The next step is to analyse the historical carbon levels as the farm systems trial progressed over a 10 year period. The samples were taken in 2004 (5 years) and 2008 (10 years) after the start of the project. The samples taken were 0-10cm and 10-30cm soil cores.
  • To determine the current soil carbon levels we will take a 0-30cm core and separate the core into 4 separate samples (0-10, 5-10, 10-20, 20-30cm) to get a good idea of how the carbon is distributed throughout the profile. Ten of these samples will be taken from each phase.
  • All of the freshly collected samples are the weighed and air dried, typically at 40 degrees Celsius for a minimum of 48 hours and then the sample mass is recorded.
  • The soil is then passed through a 2mm sieve and the mass of the retained material is recorded. A jaw crusher is occasionally used to deal with some of the more persistent aggregates that decide not to pass through.
  • A sample of 500 grams of less than 2mm soil material is further grinded down and sent away for a LECO analysis.
  • The remaining sample needs to be oven dried at 105 degrees to determine the oven soil dry weight. This is an important part in calculating bulk density.

The results from this procedure will allow us to determine which farming practises have been the best at storing soil carbon as well as maintaining soil health. For more information about how to be a member and get access to our trial results feel free to check out our member’s page.