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Interrogating the Soil

Our soil flux gas is information-rich to diagnose our planet's health.

By Richard Xu

Arid soil vs. Moist Soil: Understanding how soil chemistry & gas emissions are impacted.

Did you know that measuring ambient air isn’t the only way to examine the relationship between greenhouse gases (GHG) and our atmosphere? Our planet’s soil can actually act as a GHG source and sink that absorbs GHG making soil gas emissions’ analysis a valid metric to gauge our Earth’s health.

There are two common methods to measure these concentrations: in-ground soil gas concentration analysis and soil flux analysis, i.e. gas emitted from the soil surface.

In-ground soil gas concentration measurement or the “barhole” method involves drilling a shallow well around 50cm/20inches into the ground where probes can then measure the soil gas concentration. However, this technique can be intrusive (disturbs soil & affects its chemistry) and could potentially cross-contaminate the measurements of atmospheric and soil gases, which is raised as a valid issue experienced when the probes are inserted.

A simple diagram displaying how the “barhole” method works.

The other favored approach is the soil flux chamber measurements. Soil flux is the change in emitted concentration of gases such as methane (CH₄), carbon dioxide (CO₂), nitrous oxide (N₂O), and ammonia (NH₃) from soil and crops that remain at the soil surface over a given period of time. Positive and negative flux refer to the increase and decrease in concentration of these gases, respectively. Soil flux chambers are “non-intrusive” enclosures (when properly employed) connected via gas tubings to a gas analyzer that reside on top of the soil. The gas analyzer measures the changes in various gas concentrations inside the soil chamber over time. These devices also have the capability to recirculate the measured gases back to the chamber in order to minimize the alteration of the gas mixture composition and concentrations that might affect the true ratio of various gases produced in the mixture. This measurement pair that is comprised of a soil chamber and a gas analyzer is portable allowing for soil flux gas measurement surveys (short measurement time) to be performed at multiple locations.

Soil chambers deployment: Gas build-up within the enclosed space is recirculated through & measured by the attached analyzer (not shown).

Why is this all important? The soil gas composition reveals the status of its metabolic processes. For one, it can show overall soil health, a boon for farmers who may want to increase yield on their crops, or soil scientists who want to study the underlying phenomena. Another benefit offered is tracking of the soil-carbon cycle which also ties with agricultural production. Enabling soil health tracking allows us to monitor the bigger picture of our Earth’s health and gauge our stewardship.

How does Nikira Labs come into the picture? Nikira Labs manufactures portable soil flux analyzers for CH₄/CO₂/H₂O and NH₃/H₂O. Our fast, high-precision, real-time analyzers are compatible with most soil chambers on the market. Feel free to check out our product pages (CH₄/CO₂/H₂O & NH₃) and let us know if you have any questions or feedback.

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