Submitted to: Advances in Soil Science
Publication Type: Book / Chapter
Publication Acceptance Date: December 20, 1996
Publication Date: N/A
Experimental verification of simulation models describing soil organic matter (SOM) turnover has been hindered by our inability to isolate experimental equivalents to conceptualized SOM pools. Data collected in the past 15 years or so suggests that physically isolated SOM fractions obtained using fractionation procedures that take the soil apart in a hierarchial manner are most likely to be related to SOM structure and function in situ. In this paper, I have proposed potential experimental equivalents for input pools, the microbial biomass pool, and stabilized SOM pools have been proposed. The stabilized pools are the most difficult to verify. I have related physically isolated SOM fractions to conceptualized pools using calculated turnover times for the fractions taken from the literature, and the fraction's original location within the soil aggregate structure as guidelines for comparison. Particulate organic matter and soil macroaggregates may function as quantitative equivalents for the intermediately-labile SOM pool. There is some evidence to suggest that microaggregates and mineral-associated OM may be adequate equivalents for the passive or old SOM pool. It is anticipated that model verification using physically isolated SOM fractions will lead to a redefinition of conceptualized pools and the rate constants that control the transfer of material between these pools.