Spatial variability and temporal stability of soil organic carbon in a Mediterranean silvo-pastoral system

Abstract

Soil organic carbon (SOC) plays a vital role in determining the susceptibility to land degradation. The recommended procedure for the recovery of the characteristic poor soils of the Southern region of Portugal is the installation of grazed permanent pastures and increasing soil fertility. The objectives of this study were: i) to identify the spatial and temporal patterns of SOC and pH at four points in time over a 10-year period in a perennial pastureland; ii) to evaluate the potential for differential organic management. A 6 ha permanent bio-diverse pasture field, grazed by sheep and improved by annual application of super phospate fertilizer, was installed on a shallow soil in Mediterranean conditions. Spatial variability and temporal stability of topsoil SOC and pH were measured. The results indicate that SOC and pH have great potential for implementing differential management. In the case of SOC, the management classes map shows that over 80% of the area has temporal stability, while more than 50% of the area has low levels of SOC (<10 g kg^-1), justifying the potential for differential application of C-rich organic soil amendments.