Rapid and Cost-Effective Method for Soil Carbon Mineralization in Static Laboratory Incubations

Abstract

We evaluated a modified approach for carbon (C) mineralization using a single-cell infrared gas analyzer (IRGA). Objectives were to (i) determine if IRGA, gas chromatography (GC), and alkali absorption of carbon dioxide (CO₂) in sodium hydroxide (NaOH) have similar results over 21 days; (ii) determine how these methods correlate; (iii) estimate the limit of quantitation (LOQ); (iv) compare throughput times; and (v) estimate the concentrations of CO₂ and oxygen (O₂) that suppress respiration. IRGA did not differ from the GC and NaOH results over 21 days. Coefficients of determination (R²) for IRGA, GC, and NaOH had values of 0.92 or more. IRGA and GC had the lowest LOQ (115 and 90 ppm CO₂), with the greatest LOQ (600 ppm CO₂) found with NaOH. IRGA had the fastest sample throughput (150 h^–1), followed by 17 and 10 h^–1 for GC and NaOH, respectively. Average suppression concentrations were 5.3% for O₂ and 10.5% for CO₂.

Keywords:

• Carbon
• microbiology
• soil fertility

Acknowledgments

The authors thank Robin Montenieri, Elizabeth Pruessner, Tamara Higgs, and Dan Ruess for their expert technical assistance. Manufacturer and product brand names are given for the reader's convenience and do not reflect endorsement by the U.S. government. This article was the work of U.S. government employees engaged in official duties and is exempt from copyright.

Notes

This article not subject to U.S. copyright law.