Event Title

The T.W. Daniel Experimental Forest Soil Observatory: What have we learned about soil organic carbon quality?

Presenter Information

Helga Van Miegroet

Location

ECC 216

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

5-4-2007 6:30 PM

End Date

5-4-2007 6:35 PM

Description

Defining soil organic carbon (SOC) quality and understanding the effects of vegetation cover and climate are of central importance to determining how stable SOC will be under changing climate and/or in response to vegetation shifts. Our earlier investigations at the T.W. Daniel Experimental Forest in Northern Utah have shown that SOC in forest and rangeland soils is qualitatively very different. The challenge is to express these SOC quality differences in terms of ecologically meaningful fractions that reflect function or behavior of SOC. In the current literature, the terms “labile” and “stable” SOC are often used in very different context, and to date few comparisons have been made among them. The objective of our investigation was to compare several physical, chemical and biological SOC fractionation techniques applied to selected soil samples from conifer, aspen, sagebrush and meadow ecosystems. The methods tested included: acid hydrolysis and long-term laboratory incubations to distinguish recalcitrant from microbially accessible C; size-density fractionation to distinguish free C from that associated with the mineral fraction in various size aggregates; amount, aromaticity and bioavailability of water-extractable C; and the classical fractionation in humic and fulvic acids. Our goal was to determine overlap in results and to identify those techniques that are both practical and ecological meaningful in defining SOC stability. Our preliminary analysis reveals that while most techniques can distinguish SOC derived from different vegetation types; there is seldom a good correlation among the different measures of “labile” and “stable” C.

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Apr 5th, 6:30 PM Apr 5th, 6:35 PM

The T.W. Daniel Experimental Forest Soil Observatory: What have we learned about soil organic carbon quality?

ECC 216

Defining soil organic carbon (SOC) quality and understanding the effects of vegetation cover and climate are of central importance to determining how stable SOC will be under changing climate and/or in response to vegetation shifts. Our earlier investigations at the T.W. Daniel Experimental Forest in Northern Utah have shown that SOC in forest and rangeland soils is qualitatively very different. The challenge is to express these SOC quality differences in terms of ecologically meaningful fractions that reflect function or behavior of SOC. In the current literature, the terms “labile” and “stable” SOC are often used in very different context, and to date few comparisons have been made among them. The objective of our investigation was to compare several physical, chemical and biological SOC fractionation techniques applied to selected soil samples from conifer, aspen, sagebrush and meadow ecosystems. The methods tested included: acid hydrolysis and long-term laboratory incubations to distinguish recalcitrant from microbially accessible C; size-density fractionation to distinguish free C from that associated with the mineral fraction in various size aggregates; amount, aromaticity and bioavailability of water-extractable C; and the classical fractionation in humic and fulvic acids. Our goal was to determine overlap in results and to identify those techniques that are both practical and ecological meaningful in defining SOC stability. Our preliminary analysis reveals that while most techniques can distinguish SOC derived from different vegetation types; there is seldom a good correlation among the different measures of “labile” and “stable” C.

http://digitalcommons.usu.edu/runoff/2007/AllPosters/7