95-6 Soil Carbon Modeling Across the Continental U.S.

See more from this Division: ASA Section: Global Agronomy
See more from this Session: Symposium--The Soil-Crop Nexus Across Spatial and Temporal Scales (includes Global Digital Soil Map Graduate Student Competition)

Monday, November 4, 2013: 3:30 PM
Marriott Tampa Waterside, Florida Salon I-II

Baijing Cao, University of Florida, Gainesville, FL, Sabine Grunwald, 2181 McCarty Hall, PO Box 110290, University of Florida, Gainesville, FL, Risa Patarasuk, Soil and Water Science Department, University of Florida, Gainesville, FL, Xiong Xiong, University of Florida, Saint Paul, MN and Chris Wade Ross, Soil and Water Science, University of Florida, Gainesville, FL
Abstract:
Soils may act as a source or sink for atmospheric CO2 and climate and human activities, such as land use change impact soil carbon stocks.  Hence, insights on soil C modeling at continental scale are critical to provide significant improvements in understanding the carbon cycle. The objectives of this study were to 1) determine the historic soil C stock across the U.S.; 2) investigate the interrelationships of climate change and land use/land cover and SOC stocks within and across different ecoregions. We used soil carbon data in the topsoil (0-20 cm) and aggregated 0-100 cm depth from the U.S. National Soil Survey Database (Natural Resource and Conservation Service). Environmental covariate sets were assembled according to the STEP-AWBH model (S: soils, T: topography, E: ecology, P: parent, A: atmosphere/climate, W: water, B: biota, and H: human) as predictor variables to develop digital soil models. We used spline function to determine soil carbon concentration down to 1m and used a set of pedotransfer functions to estimate bulk density. Random forest was applied to predict soil C and analysis of variance to evaluate land use/land cover and climate change effects on soil C. Our results suggest that the prediction models have capability to estimate soil C storage accurately. The variation of soil C across the continental U.S. was governed in some regions by climate gradient while in others land use effects predominated. The soil C stock estimates can be used to infer possible changes to soil C in terms of C sequestration potential and potential C loss. Furthermore, our results provide further guidance to measure ecological variables influencing C dynamics at continental scale.

See more from this Division: ASA Section: Global Agronomy
See more from this Session: Symposium--The Soil-Crop Nexus Across Spatial and Temporal Scales (includes Global Digital Soil Map Graduate Student Competition)