(587au) Regional Variations in Soil Organic Carbon From Rotation Cropping of Rapeseed With Winter Wheat

Hydrotreated Renewable Jet (HRJ) fuel production from oilseed plants has become increasingly important in the aviation sector for energy security and climate change mitigation. Rapeseed (Brassica napus) is now considered as a feedstock for HRJ because it has high potential for producing HRJ fuel. However, land use activities from cultivation of rapeseed are one of the main causes of greenhouse gas (GHG) emissions. Changes in soil organic carbon (SOC) from cropland is caused by changes in tillage practice, cropping system, and nutrient input to soils. The purpose of current research is to evaluate regional variation of SOC of rotation cropping of rapeseed with winter wheat every 3 years (2 years for wheat and 1 year for rapeseed). The Intergovernmental Panel on Climate Change (IPCC, 2006) guidelines was modified to estimate regional differences SOC in different 10 U.S states. The tillage practices for wheat-rapeseed were assumed to be the same; full tillage, reduce tillage and no tillage. Nutrient inputs as medium and high without manure were considered as parts of IPCC method. SOC were also assumed to be zero when wheat and rapeseed have been applied in the same tillage practice and the same nutrient inputs due to considering as no land use change activity. The results showed that different tillage practices and nutrient inputs in cropping system could have significant impacts on regional SOC. Moreover, in the case of no tillage practice with medium input for wheat and high without manure input for rapeseed in different regions showed the best result of increasing in soil carbon stocks. The results range between 0.41 – 1.59 ton C year^-1 or 34.27 – 132.88 g CO₂/MJ HRJ. On the other hand, carbon stocks in soil were the lowest when full tillage practice with high without manure input for wheat and medium input for rapeseed were applied due to loss of carbon stock in soil where the range are in between (-0.37) – (-1.38) ton C year^-1 or (-31.03) – (-115.52) g CO₂/MJ HRJ.