Using 137Cs to study spatial patterns of soil erosion and soil organic carbon (SOC) in an agricultural catchment of the typical black soil region, Northeast China

Understanding the spatial pattern of soil organic carbon (SOC) is of great importance because of global environmental concerns. Soil erosion and its subsequent redistribution contribute significantly to the redistribution of SOC in agricultural ecosystems. This study investigated the relationships between 137Cs and SOC over an agricultural landscape, and SOC redistribution was conducted for an agricultural catchment of the black soil region in Northeast China. The spatial patterns of 137Cs and SOC were greatly affected by the established shelterbelts and the developed ephemeral gullies. 137Cs were significantly correlated with SOC when 137Cs were >2000 Bq m−2, while no relation was observed between them when 137Cs were <2000 Bq m−2. Factors other than soil erosion such as vegetative productivity, mineralization of SOC, landscape position and management induced their spatial difference of 137Cs and SOC. Using 137Cs technique to directly study SOC dynamics must be cautious in the black soils. The net SOC loss rate across the entire catchment during 1954–2010 was 92.8 kg ha−1 yr−1, with around 42% of the eroded SOC being redeposited within the catchment. Such information can help guide shelterbelt establishment or other land management to reduce SOC loss in the agricultural ecosystems.

► 137Cs and SOC patterns are affected by the shelterbelts and ephemeral gullies.
► There are no general relations between 137Cs and SOC.
► Using 137Cs to directly study SOC dynamics must be cautious.
► SOC displacement is greatly affected by soil redistribution.