  A novel model is here introduced for the SOC change index defined as the
normalized difference between the actual Soil Organic Carbon and the value
assumed at an initial reference year. It is tailored on the RothC carbon model
dynamics and assumes as baseline the value of the SOC equilibrium under
constant environmental conditions. A sensitivity analysis is performed to
evaluate the response of the model to changes of temperature, Net Primary
Production (NPP), and land use soil class (forest, grassland, arable). A
non-standard monthly time-stepping procedure has been proposed to approximate
the SOC change index in the Alta Murgia National Park, a protected area in the
Italian Apulia region, selected as test site. In the case of arable class, the
SOC change index exhibits a negative trend which can be inverted by a suitable
organic fertilization program here proposed.
