Effects of grazing exclusion on soil organic carbon: Hillslope and soil profile results (an Australian example)

Soil organic carbon (SOC) is an essential component of the soil-landscape system. It is well recognised that SOC can reduce under some agricultural management practices. In recent years a concerted effort has been undertaken to increase SOC by employing different landscape management practices. Here we compare SOC in a grazing environment to that of an area where cattle have been excluded for over ten years using both a hillslope and whole of soil profile sampling strategy. Surface SOC concentrations (determined by cores) were significantly higher inside the exdusion area when compared to that outside demonstrating a rapid increase in SOC. Whole soil profile (to bedrock) assessment found that SOC decreased with depth both inside and outside of the shelterbelt. While SOC decreased with depth, there were significantly higher surface concentrations inside the exdusion area compared to outside. At depths >20 cm, SOC became increasingly homogenous for both datasets with little difference observed. The results suggest that the influence of the exdusion area on SOC accumulation at the site was only within the top 10-20 cm of the soil profile. The results highlight the importance of soil depth in quantifying SOC within the soil profile and SOC sequestration potential for sites at depth. Crown Copyright (C) 2018 Published by Elsevier B.V. All rights reserved.