Short-term C mineralization (aka the flush of CO 2 ) as an indicator of soil biological health.

Abstract

Abstract Soil biological activity is a key component of soil health assessments, as it (a) indicates soil nutrient cycling capacity from various organic matter sources to inorganic availability, (b) relates to soil structural conditions, (c) informs about the potential to harbour biodiversity in soil and (d) often parallels changes in soil organic C and N storage in surface soils. The flush of CO 2 following rewetting of dried soil represents a burst of microbial activity that can be considered an artefact, but has a strong relationship with longer-term C mineralization and basal soil respiration across a diversity of soils. This review demonstrates also the strong association of the flush of CO 2 with soil microbial biomass C and net N mineralization. Weaker associations occur with total and particulate organic C and N. The flush of CO 2 has been evaluated for assessing both short- and long-term impacts of crop and forage management. It also has strong temporal and spatial variations that can be related to the availability of organic substrates and landscape-specific environmental conditions. Variations in methodology have recently appeared in the literature and standardization is needed if results are to be compared. The flush of CO 2 should be considered a rapid, robust and reliable method to indicate soil biological activity and as such should be a major component of any soil health assessment.