The Role of Soil Organic Matter and Manures in Sustainable Nutrient Cycling - Sustainable Management of Soil Organic Matter - page 319

Fig. 4.13.2. Carbon mitigation potential in agriculture. (a) The pre-Kyoto estimates based on
Smith et al. (1997a,b, 1998; Paustian et al., 1997). (b) Post-Kyoto estimates based on revised sce-
narios including a 1990 baseline condition (Smith et al., 2000).
determining SOC changes under a given management. The simplest
approach is to use statistical relationships derived from experiments (as
above and Smith et al ., 1996). Where uncertainty has been estimated (95%
confidence interval), it can be as high as 50% (Smith et al ., 1998). Using
dynamic simulation models (Smith et al ., 1997c) may reduce this error,
though this has yet to be demonstrated. The second source of uncertainty
arises from the spatial soil-climate data used in the scenarios. In the
examples above, differences in soil and climate are subsumed within the
statistical relationship derived. Uncertainty would be reduced by including
a spatially explicit description of soils and climate either linked to statistical
models (e.g. Kern and Johnson, 1993) or, more desirably, linked to
dynamic simulation models (e.g. Donigian et al ., 1984; Falloon et al ., 1998,