Problems In Modeling Soil Carbon Dynamics

A more general problem yet faces soil ecologists. One of our current needs is to "model the measurable," rather than "measure the modellable" (Elliott, 1994). There are pools in models such as Century, mentioned earlier, that are more easily conceptualized than actually measured. A more readily measurable entity is the labile pool, consisting primarily of the microbial biomass. The intermediate and long-term pools, existing from decades to millennia, are very difficult to measure directly, and much work is under way to more effectively isolate and characterize these pools by a variety of methods (Six et al., 2002a, b). This problem requires integration across several levels of resolution, dealing with numerous human activities in sociology and economics that have a direct impact on soil management. These include the concept of the effectiveness of management of carbon resources, which is inversely related to the cost of subsidizing the lost functions of organic matter (Fig. 8.4) (Woomer and Swift, 1995). The effectiveness of carbon resource management decreases with sequential loss of constituents and subsequent loss of function as land use intensifies without subsidizing lost organic matter. Elliott (1994) and colleagues urged soil ecologists to isolate functional soil organic matter fractions and determine their roles in soil processes in order to understand the mechanisms controlling soil processes. This includes the mechanisms and processes


Soil carbon constituents

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