Solvita: A New, Rapid Test for Active Soil Carbon, and Potential N-Mineralization.

Evolution of soil carbon dioxide (CO2) is a means to gauge biological soil fertility. The new Solvita technology enables rapid and accurate detection of soil CO2 evolution and is well correlated with traditional base/trap & IRGA. Our 24h drying rewetting CO2-burst_ protocol closely corresponds to longer term CO2 tests (3d, 7d, 21-28d). CO2 burst could be used to predict N-release. To date, measuring potential N-mineralization includes cumbersome methods that have not proved cost-effective as indicated by limited adoption by soil laboratories. Flush of carbon dioxide following rewetting of dried soil relates to active organic pools. The pressing need exists to better estimate crop N-requirements to reduce costly fertilization and ameliorate surface and groundwater nutrient-contamination. We apply the CO2-burst test as a measure for potential N-min. The ability of soils to supply N from organic humus reserves must be better appreciated. We show the use of the Solvita test to indicate carbon turnover, biomass and potential N-mineralization. It closely correlates to 7d anaerobic protocols and 28d incubation mineralization. Widespread adoption of the new test would be cost-effective for soil labs, potentially saving farmers money on fertilization, and reducing nutrient pressure on surface and groundwater.