ABSTRACT
This chapter utilizes a time-step one-box model and bulk soil radiocarbon measurements to estimate turnover times and inventories of active and passive carbon. The turnover of soil organic nitrogen can also be inferred from these measurements. This model reproduces the prebomb soil radiocarbon values and the post-bomb increase in radiocarbon values in native soil. The model can be further validated by seeing if derivatives could explain radiocarbon measurements in cultivated and recovering soil. The radiocarbon results suggest that soil carbon exchanges significant amounts of carbon with the atmosphere, having the potential to respond to perturbations. Having estimated the turnover time and inventory of fast cycling soil carbon, it is possible to estimate the amount of carbon potentially stored in soil because of CO2 fertilization. The increase in soil carbon storage due to CO2 fertilization may potentially explain most of the "missing sink".
