Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2008
Publication Date: 10/1/2008
Citation: Haney, R.L., Brinton, W.H., Evans, E. 2008. Estimating soil carbon, nitrogen, and phosphorus mineralization from short-term CO2 respiration. Communications in Soil Science and Plant Analysis. 39(17&18):2706-2720. Interpretive Summary: Soil testing labs currently offer limited methods to determine soil health. Soil health is largely defined by the activity of soil microorganisms. These soil microbes produce “free fertilizer” by recycling nitrogen and phosphate compounds in soil decaying plant and animal material. This article demonstrates new methods that can be used by commercial soil testing labs which will provide a rapid and accurate analysis of microbial activity. These methods can then be used to increase the accuracy of fertilizer recommendations which would help protect the environment and make us more efficient with our fertilizers, which should result in cutting fertilizer costs for agricultural producers.
Technical Abstract: The measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. A new method to measure soil respiration was tested along with the traditional alkali trap and titration method. The new method involves the Solvita gel system which was originally designed for CO2 respiration from compost, but has been applied in this research to soils with treatments of increasing dairy manure compost. The objective of this research is to: (1) examine the relationship between the CO2 release after one day of incubation from soils amended with dairy manure compost that have been dried and rewetted as determined using the titration method and the Solvita gel system; and (2) compare water-soluble organic N, as well as C, N, and P mineralization after 28 days of incubation with 1-d CO2 release from the titration method and Solvita gel system. Both 1-day CO2 from titration and the Solvita gel system were highly correlated with cumulative 28 day CO2 as well as the basal rate from 7-28 days of incubation. Both methods were also highly correlated with 28 day N and P mineralization as well as the initial water extractable organic N and C concentration. 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 and possibly provide an estimate of potential mineralizable N and P. 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.