The role of check dams in retaining organic carbon and nutrients. A study case in the Sierra de Avila mountain range (Central Spain)

Soil organic carbon plays an important role in the global carbon cycle, accounting for 70% of the Earth's carbon. However, soil erosion can have a major impact on the stocks of soil carbon and other soil nutrients, such as nitrogen and phosphorous. Soil and water conservation techniques, such as the building of check dams, are usually employed to control sediment yields and the losses of other soil components. The aim of this research is thus to quantify the soil organic carbon (SOC), soil nitrogen (SN) and soil phosphorous (SP) retained by the check dams of a hydrologic and forest restoration project in the Sierra de Avila mountain range (Avila, Central Spain). Soil samples were taken from the sediment wedges of 30 check dams and from 30 native soils. Soil texture, electric conductivity, pH, C, N and P were measured in all the soil samples. The volume of sediment retained by the check dams was calculated by the Sections Method, which is very accurate in estimating the real volume of the sediment. wedges. The total sediment yield in the area was thus estimated at 6.40 Mg.ha(-1).yr(-1) and the mean SOC, SN and SP densities were respectively 13.76, 0.48 and 0.05 kg.m(-2). These findings thus are very reliable and allow us to conclude that check dams constitute an important instrument for controlling losses of SOC, SN and SP, and preventing these substances from passing into watercourses downstream of the area. (C) 2018 Elsevier B.V. All rights reserved.