An Automated Laboratory Method for Measuring CO₂ Emissions from Soils

Abstract

A gas chromatography (GC) headspace method was developed for soil microbial respiration (CO 2 emission) analysis after a 24-h incubation of a rewetted soil. The GC method was compared with the Solvita CO 2 burst method by analyzing 18 diferent soils that were air-dried (22°C) or dried at 45, 65, and 105°C for 24 h before rewetting. A strong exponential relationship between the Solvita color number and GC headspace CO 2-C emission was observed. Compared with air-dried soils, drying at 65°C led to increased CO 2 emission and reduced variation among sample replicates, while drying at 105°C led to a reduction in CO 2 emission and an increase in variability. The GC method does not require sample dilution, provides data that is highly correlated to the Solvita method, and has a wider dynamic test range than the Solvita method. The developed GC method could be adapted to automation for commercial laboratory use.

Effect of Sieving on Ex Situ Soil Respiration of Soils from Three Land Use Types

“…Measurement of soil respiration is therefore important for quantifying the flux of CO 2 to the atmosphere from soils. Soil CO 2 flux also represents the activity of soil biological communities, thereby serving as a valuable indicator of soil health (McGowen et al 2018).…”

“…Whereas in situ measurements are more representative of the actual field conditions (Gabriel and Kellman 2011), ex situ measurements can be used to apply treatments in a systematic manner and are thus very useful. Soil respiration can be measured ex situ on intact cores (Hangs et al 2016;Meyer et al 2019), fresh soil sieved with mesh sizes ranging 2 mm to 5 mm (Thomson et al 2010;Datta et al 2014), or (most frequently) air-dried soil sieved to 2 mm (Mathur and Sanderson 1978;Valerie and Cook 1983;Thuries et al 2000;Thomson et al 2010;McGowen et al 2018). Sieving and homogenisation prior to incubation (often favoured by researchers to create replicates appropriate for statistical analysis) disrupt the original architecture of the soil experienced by decomposer organisms (Baveye et al 2018) and may influence the soil respiration measurement.…”

Comparison of two alkali trap methods for measuring the flush of CO2

“…We wanted to compare the relative relationship between the CASH respiration method and a standard research method used in the Soil Ecology and Management (SEM) lab (Franzluebbers, 2018a; Franzluebbers et al., 2000), which shares similarity in multiple‐day incubation with alkali trap to detect CO 2 evolution, but has differences in other features. Other common CO 2 detection approaches include a commercially available kit with gel paddle (Brinton & Vallotton, 2019; Haney et al., 2008), infrared gas analyzer (Sherrod, Reeder, Hunter, & Ahuja, 2012), and gas chromatograph (McGowen, Sharma, Deng, Zhang, & Warren, 2018).…”

Sampling probes affect bulk density and soil organic carbon measurements

“…Soil organic carbon (SOC) is an important component and indicator of soil health (McGowen, Sharma, Deng, Zhang, & Warren, 2018). However, estimating SOC stocks is challenging due to spatial and temporal variation in soil properties (Post et al, 2001).…”