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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #204416
Title: Soil CO2 respiration: Comparison of chemical titration, CO2 IRGA analysis and the Solvita gel system

Author
item Haney, Richard
item BRINTON, W - WOODS INN LABORATORIES
item EVANS, ERIC - WOODS INN LABORATORIES

Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2008
Publication Date: 6/1/2008
Citation: Haney, R.L., Brinton, W.F., Evans, E. 2008. Soil CO2 respiration: Comparison of chemical titration, CO2 IRGA analysis and the Solvita gel system. Renewable Agriculture and Food Systems. 23:171-176.

Interpretive Summary: Soil microbes are sensitive to changes in the soil. Using this new Solvita gel system, soil testing labs can offer a method that would be useful in tracking the impact of management inputs (fertilizers, pesticides, tillage, etc.) on the health of the soil microbes. We can then begin to change our management decisions based on a living soil system instead of the current chemical system, which would help protect the environment and make us more efficient with our fertilizers.

Technical Abstract: The purpose of this research is to compare the results of measured soil CO2 respiration using three methods: (1) titration method; (2) Infrared gas analysis (IRGA); and (3) the Solvita gel system for soil CO2 analysis. We acquired 36 soil samples from across the USA for comparison which ranged in pH from 4.5-8.5, organic C from 0.8-4.6% and the clay content from 6-62%. All three methods were highly correlated with each other after 24 hr. of incubation (titration and Solvita r**2=0.82, respirometer and Solvita r**2=0.79 and titration vs. respirometer r**2=0.95). The 24 hr. (1-day) CO2 release from all three methods was also highly correlated to both basal soil respiration (7-28 d) and cumulative 28 d CO2 respiration. An additional 24 soil samples were acquired and added to the original 36, for a total of 60 soil samples. These samples were used for calibration of the Solvita gel digital reader results using CO2-titration results and regression analysis. Regression analysis resulted in the equation y=20.6*(Solvita number)-16.5 with an r**2 of 0.83. The data suggest that the Solvita gel system for soil CO2 analysis could be a simple and easily used method to quantify soil microbial activity. Once standardized soil sampling and laboratory analysis protocols are established, the Solvita method could be easily adapted to commercial soil testing labs as an index of soil microbial activity.