ABSTRACT
This chapter focuses on verification of simulation models that describe long-term soil organic matter (SOM) turnover. SOM turnover is coupled to the cycling of nutrients in soil and the agradation/degradation of soil aggregates through the activity of soil microorganisms. The rate of turnover rate of SOM varies due to the interaction of complex biological, chemical, and physical processes in soil. Most SOM turnover models are modifications of the Rothamsted model proposed in the late 1970s by Jenkinson and Raynor. The Long-term Organic Carbon model proposed by van Veen and Paul and the CENTURY model of Parton et al. were chosen because of their similarity in structure to the Rothamsted model. All three models have a decomposable and resistant input pool, a microbial biomass pool, and several labile and stabilized SOM pools differentiated by turnover rate and carbon/nitrogen ratio. Verification of SOM pools conceptualized in simulation models has been hindered by inability to isolate experimental equivalents to these pools.
