A novel model for soil organic Carbon change: sensitivity Analysis of soc change index to Changes of temperature, net Primary production and land use

Soil organic carbon (SOC) is one of the most important indicators of land health. In fact, soil fertility increases with increasing SOC, while reductions in SOC stocks are indicative of soil degradation. Since our main interest is to analyse these variations, we define the SOC change index as the difference between the current SOC and the value assumed at an initial reference year, normalized by the initial carbon inputs; then we introduce a novel model for the SOC change index [1], tailored on the RothC carbon model dynamics [2]. In order to evaluate the local response of the model to changes of temperature, Net Primary Production (NPP), and land use soil class (forest, grassland, arable), a sensitivity analysis, based on the direct method, is performed. Moreover, we use this novel model to approximate the SOC change index in the Alta Murgia National Park, a protected area in the Italian Apulia region, selected as a test site, and our results indicate positive trends for SOC change in the case of both forest and grassland systems. Whereas, when the arable class is considered without including the input of farm fertilizers, the SOC change index exhibits a negative trend which can be inverted by a suitable organic fertilization program here proposed.