Simulating soil organic carbon change in oilseed cropping systems in North Dakota

Authors: Lee, Joon Hee; Archer, David

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 6/6/2014
Publication Date: 7/13/2014
Citation: Lee, J., Archer, D.W. 2014. Simulating soil organic carbon change in oilseed cropping systems in North Dakota. Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE). Paper number 14188717. ASABE-CSBE Joint Meeting, Montreal, Quebec, Canada. July 13-16, 2014. DOI: 10.13031/aim.20141888717.

Interpretive Summary: An important driver for the use of renewable fuels is reduction in greenhouse gas (GHG) emissions. The amount of greenhouse gas emissions achieved determines the crops or other biomass sources that can be used to meet the U.S. renewable fuels standard. Soil organic carbon (SOC) change is a key measure for calculating GHG emission from cropping systems. The EPIC model was used to simulate soil organic carbon changes for growing rapeseed for use as a biofuel in rotation with spring wheat. Field research data were used in adjusting the model and to measure how well the model was able to predict soil organic carbon changes. The results showed soil organic carbon would increase if rapeseed was grown in rotation with wheat on all soil types within Ward County, North Dakota. These results indicate that GHG emissions might be reduced in growing rapeseed for biofuel use. The results are useful to researchers, biofuel industry, and regulators in determining the net GHG impacts of using rapeseed for fuel production and whether rapeseed may be used a feedstock in producing biofuels that meet the U.S. renewable fuels standard.

Technical Abstract: An important driver for the adoption of renewable fuels is reduction in greenhouse gas (GHG) emissions, and the quantity of greenhouse gas reductions achieved is used in determining the fuel feedstocks and conversion pathways that can be used for fuels to meet the U.S. renewable fuels standard. Estimating GHG emissions from cropping system is an important component in quantifying GHG emissions through entire process from feed stock to final product use for oilseed based renewable fuels. Soil organic carbon (SOC) change is a key measure for calculating GHG emission from cropping systems because increase of SOC is regarded as CO2 deposition from atmosphere to soil. Even though many researchers have simulated long term impacts of cropping system on SOC, the calibration and validation for C dynamic parameters using long-term soil profile data have been limited. The objective of this study is modeling long-term SOC change under impact of Brassica oil seed cropping systems with calibration and validation of soil C dynamics parameters in the EPIC model. We validated crop growth parameters from several areas of Northern Great Plains regions using field scale crop yield and management data at Mandan, ND. Soil C dynamics parameters (microbial decay rate coefficient) were calibrated and validated using soil profile data in 1983, 1991 and 2001 from long-term soil quality studies conducted at Mandan, ND since 1983. After calibration and validation, SOC and crop yields were modeled for each SSURGO soil map unit in Ward County, ND, one of pilot counties being evaluated for potential oilseed supply for hydrotreated renewable jet fuel production. The simulation was conducted under two rotation scenarios, canola-spring wheat-spring wheat and continuous spring wheat with no-tillage. The soil parameters from SSURGO were initialized by 100 year run with continuous spring wheat before imposing the two rotation scenario treatments. The results from 50-year simulation indicate that the canola cropping system is beneficial to store SOC compared to continuous spring wheat in all test map units. However, differences vary across soil map units.