The Machine

How it works

The Yeomans Carbon Still has slowly evolved into a very accurate
device for measuring changes in soil carbon levels. It can now test
individual soil samples weighing up to 2,000 grams with a 1 gram accuracy.

In the Carbon Still an air flow, at a preselected temperature, passes
directly through the sample material. Intermittent contact between
soil and air seems thus assured. A complete test takes about 3 hours.

In the unit the central oven is decoupled for weighing from both its
heating elements and air supply. This allows a soil sample to be
weighed without its removal from the heating oven.

In the Carbon Still a sample is heated to 110 degrees Celsius and
weighed. It is then heated to 500 degrees Celsius at which temperature
all contained organic matter is completely burnt off. It is then
reweighed. The difference is the Loss On Ignition (LOI) for the

The LOI value is directly proportional to the CO2-e (carbon dioxide
equivalent) sequestered into the soil.

In a future carbon economy, farmers must be paid for sequestering
carbon from the atmosphere into their soils through regenerative
agriculture – however there is much work to be done to create the
technical, economic and governance systems to enable such financial
incentives to be implemented.

The Yeomans Carbon Still can be shipped at a fraction of the cost of other soil carbon testing equipment. This affordability is essential if farmers are to be paid adequately for their work sequestering carbon.

For more information about the Yeomans Carbon Still and its accompanying methodology for accurately measuring soil carbon levels, visit this page.

Contact us: 
Allan Yeomans –
Dr Lucas Ihlein –