Stratification ratio of soil organic C, N and C:N in Mediterranean evergreen oak woodland with conventional and organic tillage

TheMediterraneanevergreenoakwoodland(MEOW-dehesa)is themostwidespreadagroforestry system in Mediterranean Europe and integrates forestry, agricultural and livestock practices. The MEOW-dehesa is a grazing system with evergreen Quercus ilex spp. ballota. It is characterized by the conservation of forest oaks (Quercus spp.) and provides environmental benefits such as carbon capture and storage in soils. The effect of conventional tillage (CT) and organic tillage (OT) on the distribution of soil organic carbon (SOC), total nitrogen (TN) and C:N ratios has not been well documented in the MEOW-dehesa. The objective of this paper is to study these parameters in the MEOW-dehesa in two soil types (Leptosols and Cambisols) and two management systems, OT for 20 years and CT. The stratification ratio (SR) of SOC, TN and C:N ratio is also evaluated. An analysis is performed on 85 soil profiles over the 2005–2009 period in southern Spain. The SR of SOC in Cambisols was greater under OT than CT, ranging from 1.25 to 1.42 and from 1.3 to 1.6 under CT and OT, respectively. The SR of TN for 0–20.9 cm, 20.9–55.5 cm and 55.5–102.1 cm depth was greater under OT than under CT. The OT also increased the stratification of the C:N ratio compared to CT.