Abstract
Abstract. There is increasing recognition that lateral soil organic carbon (SOC) fluxes due to erosion have imposed an important impact on the global C cycling. Field and experimental studies have been conducted to investigate this topic. It is useful to have a modeling tool that takes into account various soil properties and has flexible resolution and scale options so that it can be widely used to study relevant processes and evaluate the effect of soil erosion on SOC cycling. This study presents a model that is capable of simulating SOC cycling in landscapes that are subjected to erosion. It considers all three C isotopes (12C, 13C and 14C) with flexible time steps and a detailed vertical solution of the soil profile. The model also represents radionuclide cycling in soils that can assist in constraining the lateral and vertical redistribution of soil particles within landscapes. The model gives a three-dimensional representation of soil properties including 137Cs activity, SOC stock, and δ13C and Δ14C values. Using the same C cycling processes in stable, eroding and depositional areas, our model is able to reproduce the observed spatial and vertical patterns of C contents, δ13C values, and Δ14C values. This indicates that at the field scale with a similar C decomposition rate, physical soil redistribution is the main cause of the spatial variability of these C metrics.
Highlights
Soil organic carbon (SOC) is the largest organic C pool on land, with approximately 1550 Pg C in the upper meter of soil (Lal, 2008)
This paper presents a model (WATEM_C) that is capable of simulating SOC dynamics on an eroding landscape
Model calibration shows that the model is able to reproduce the observed spatial pattern of SOC stock: eroding soil profiles are depleted of SOC compared to the stable soil profile, while the depositional soil profile is more enriched in SOC than the stable soil profile
Summary
Soil organic carbon (SOC) is the largest organic C pool on land, with approximately 1550 Pg C in the upper meter of soil (Lal, 2008). This is about 2 times the C in the atmosphere SOC stock decreases with increasing temperature (Jobbágy and Jackson, 2000). Land use is another important factor because different vegetation supplies SOC to the soil at different rates (Mahowald et al, 2017; Maia et al, 2010). SOC can be enriched in 13C during the processes of SOC degradation due to preferential mineralization of 12C (Natelhoffer and Fry, 1988)
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