Presentations and Publications A.N. (Thanos) Papanicalaou, Kenneth M. Wacha, Benjamin K. Abban, Christopher G. Wilson, Jerry Hatfield, Charles Stanier, and Timothy Filley. From Soilscapes to Landscapes: A Landscape-oriented Approach to Simulate Soil Organic Carbon Dynamics in Intensely Managed Landscapes. J. Geophys. Res. Biogeosci., 120, 2375–2401, doi:10.1002/2015JG003078. Most available biogeochemical models focus within a soil profile and
cannot adequately resolve contributions of the lighter size fractions of
organic rich soils for enrichment ratio (ER) estimates, thereby causing
unintended errors in soil organic carbon (SOC) storage predictions.
These models set ER as constant, usually equal to unity. The goal of
this study is to provide spatiotemporal predictions of SOC stocks at the
hillslope scale that account for the selective entrainment and
deposition of lighter size fractions. It is hypothesized herein that ER
values may vary depending on hillslope location, Land Use/Land Cover
(LULC) conditions, and magnitude of the hydrologic event. An ER module
interlinked with two established models, CENTURY and Watershed Erosion
Prediction Project, is developed that considers the effects of changing
runoff coefficients, bare soil coverage, tillage depth, fertilization,
and soil roughness on SOC redistribution and storage. In this study, a
representative hillslope is partitioned into two control volumes (CVs): a
net erosional upslope zone and a net depositional downslope zone. We
first estimate ER values for both CVs I and II for different hydrologic
and LULC conditions. Second, using the improved ER estimates for the two
CVs, we evaluate the effects that management practices have on SOC
redistribution during different crop rotations. Overall, LULC promoting
less runoff generally yielded higher ER values, which ranged between
0.97 and 3.25. Eroded soils in the upland CV were up to 4% more enriched
in SOC than eroded soils in the downslope CV due to larger interrill
contributions, which were found to be of equal importance to rill
contributions. The chronosequence in SOC storage for the erosional zone
revealed that conservation tillage and enhanced crop yields begun in the
1980s reversed the downward trend in SOC losses, causing nearly 26% of
the lost SOC to be regained.
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