Free-air Concentration Enrichment and K30 1% CO2 Sensor |


Free-air Concentration Enrichment and K30 1% CO2 Sensor

CO2 K30 CO2 Sensor and Free Air Concentration Enrichment

CO2Meter continues to collaborate with an abundance of universities, researchers, and scientists who all share the same mission towards achieving success and leading advancements in technology and innovation.

One fascinating research project this past month involves a soil scientist utilizing our own CO2 sensors in FACE (free-air CO2 enrichment) research. 

The method of free-air CO2 enrichment stems back to the 90s and is still used by many ecologists, scientists, and biologists that raise concentrations of CO2 in specific environments which fundamentally allow the response of plant growth to be measured. By measuring the effects of elevated carbon dioxide concentrations and implementing the FACE method the researcher is given a  much more natural route in regards to estimating how crops will alter in the future -  alongside rising CO2 concentrations in the atmosphere.

A typical method that shows free-air concentration enrichment would typically mimic either horizontal or vertical pipes being placed in a circle around the experimental site and range anywhere from 1m - 30m in diameter. The circle would then emit CO2 enriched air amongst the crops.

Today, many FACE methods can be seen across the United States and in the areas of aspen Italy.

In reaching out to customer Bruce K., CO2Meter was very intrigued by the overall study and the compilation of Bruce's research in regards to FACE methodology and wheat or cotton growth. Bruce was kind enough to share his feedback not only in regards to his experimental analysis but also in his research using the K30 10,000ppm CO2 Sensor Development Kit (CM-0024).

Bruce stated, "I am still trying to evaluate the K30 sensor and this application. I first connected the sensor to my desktop and also a laptop via the USB, and was able to log CO2 concentrations using GasLab software. I could see that it responds to the CO2 changes well. However, we want to connect many sensors to a Scientific Data Logger, which will be able to log 16 of the K30 sensors at the same time". 

In gaining Bruce's feedback in regards to the capabilities and integration of the K30 sensor in providing accurate concentration readings, the team at CO2Meter became quite fascinated with his experiments and discovered much more on the importance of free-air concentration enrichment methodology in the field. 

Bruce Kimball FACE Methodology Experiiment

Picture of Bruce in and photo of the FACE ring enriching air above a cotton plant with CO2 at 550ppm. 

The CO2Meter team gained a variety of insights into Bruce's FACE experiments and the importance of the K30 10,000ppm CO2 Sensor to the environmental research project.

Could you tell us how you got started with this project, and what was the key motivator in regards to FACE enrichment?

"It is simply premature. I started using CO2 analyzers over 40 years ago to monitor and control CO2 concentrations in order to increase the growth of the crops in greenhouses and to determine the likely effects of the increasing atmospheric CO2 concentration on future crop productivity and water use."

K30 10,000ppm CO2 Sensor

How has CO2Meter's sensor technologies assisted any in your overall research towards FACE enrichment?

Bruce: "Overall I have used analyzers from other manufacturers and am just now trying to evaluate yours for this application. Your sensor is far less expensive than previous analyzers I have used, and the accuracy and resolution specifications while not as good; are adequate. Future colleagues will be using your K30 sensors for additional FACE applications in almond orchards in the coming weeks".

Could you provide additional insights into your research specifically with FACE from the coming years for added insights?

From Bruce's abstracts in 1955 from the Global Change Biology, it states, "We depicted a free-air CO2 enrichment (FACE) experiment in Arizona on wheat from December 1992 through May 1993. The Face apparatus maintained the CO2 concentration at 550 mol across four replicate 25m diameter circular plots under natural conditions in an open field. Four matching control plots at ambient CO2 were also installed in the field. Net canopy photosynthesis was stimulated by an average 19 and 44% in the wet and dry plots, respectively, by elevated CO2 for most of the growing season. No significant acclimation or down-regulation was observed. There was little above-ground response to elevated CO2 early in the season when temperatures were cool. Then, as temperatures warmed into spring, the FACE plants matured and grew about 20% more than the control plants at ambient CO2, as shown by the above-ground biomass accumulation". 

In what ways does your industry use Carbon Dioxide?

"As a feedstock for photosynthesis, elevated CO2 can accelerate plant growth and could potentially increase agricultural productivity. Doubled CO2 concentrations have been shown to increase crop yields by 30% or more on the average, in experiments conducted mostly under greenhouse and growth chamber conditions."

Overall, what were some of the results from monitoring CO2 and common observations from the FACE methodology and research?

"One commonly observed response to the elevated CO2 is partial stomatal closure with a concomitant reduction in stomatal conductance to water vapor. Consequently, the rate of loss of water from the leaves or transpiration is slowed. Of course, solar, radiation, wind speed, and air temperature and humidity are also important weather factors that determine rates of transpiration as well as evaporation from the soil."

"Cotton had a larger growth response to elevated CO2, and therefore showed almost no reduction in ET under elevated CO2. In contrast, sorghum and maize, both C4 species, had little or no photosynthetic growth responses to elevated CO2, so they had large reductions in ET of about 13%. Wheat and rice were intermediate in both growth and ET responses." 

In addition to gaining key insights from Bruce and his prior research in the field, CO2Meter continues to recognize the large impact that carbon dioxide and other gas concentrations are able to play in regards to improving plant yields, agricultural implementation, and even free-air concentration enrichment.

For more information on CO2Meter sensing technologies, click here


  • Kimball, B. (2016). Crop Responses to elevated CO2 and interactions with H20, N, and temperature. Plant Biology Science Direct.

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