Dr. Daniel Liptzin: Effects of Soil Health Management Practices on Soil Carbon Dynamics

Carbon has long been considered central to soil health because it plays many roles in soil function. Measuring total soil carbon has been possible for decades, but many other soil carbon measurements have been proposed recently to quantify soil health. These alternative indicators measure some type of biological activity or chemical fraction of carbon and are thought to be more sensitive to management decisions. The Soil Health Institute, through the North American Project to Evaluate Soil Health Measurements (NAPESHM), compared soil organic carbon (SOC) measurements with permanganate oxidizable carbon (POx-C), respiration, microbial biomass, water-extractable organic carbon, and beta-glucosidase enzyme activity.

Preliminary results show that correlations of indicators with climate and soil texture were weak. The correlations among the indicators were moderate, except for microbial biomass which was weak. All of the indicators (except microbial biomass) had a similar capability to detect changes in management. While the cost of most of these tests is similar, the POx-C and 24 hour respiration assays have advantages of being widely available at commercial labs and offer the option of a “field” test. These tests are suggested to respond quickly to changes in management.

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