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Title: Should soil testing services measure soil biological activity

item Franzluebbers, Alan

Submitted to: Agricultural and Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2015
Publication Date: 2/9/2016
Citation: Franzluebbers, A.J. 2016. Should soil testing services measure soil biological activity? Agricultural and Environmental Letters. doi:10.2134/ael2015.11.0009.

Interpretive Summary: Soil health is an important concept for managing the productivity and resiliency of agricultural soils in the face of climate change and rising input costs. An ARS scientist in the Plant Science Research Unit in Raleigh NC described a simple, rapid, inexpensive, and yet robust procedure that could be more widely used by soil testing services to quantify soil biological activity as a component of soil health assessment. Calibration studies to relate the flush of CO2 following rewetting of dried soil to nitrogen mineralization under laboratory conditions have been conducted, and new studies are underway to calibrate the soil test values to plant growth under greenhouse conditions and crop yield under field conditions.

Technical Abstract: Health of agricultural soils depends largely on conservation management to promote soil organic C accumulation. Total soil organic C changes slowly, but active fractions are more dynamic. A key indicator of healthy soil is potential biological activity, which could be measured rapidly with soil testing services via the flush of CO2 during 1 to 3 days following rewetting of dried soil. The flush of CO2 is related to soil microbial biomass C and has repeatedly been shown strongly related to net N mineralization during standard aerobic incubations. New research is documenting the close association with plant N uptake in semi-controlled greenhouse conditions. Field calibrations are underway to relate the flush of CO2 to the need for in-season N requirement in a variety of crops. Soil biological activity can and should be determined to help predict N availability.