Int J Life Cycle Assess (2012) 17:58–68 DOI 10.1007/s11367-011-0337-z

Carbon footprint of canola and mustard is a function of the rate of N fertilizer

Yantai Gan & Chang Liang & Gaobao Huang & Sukhdev S. Malhi & Stewart A. Brandt & Felicitas Katepa-Mupondwa

Received: 19 April 2011 /Accepted: 6 September 2011 /Published online: 28 September 2011 # Springer-Verlag 2011

Abstract Purpose Bestagriculturalpracticescanbeadoptedtoincrease crop productivity and lower carbon footprint of grain products.Theaimsofthisstudyweretoprovideaquantitative estimate of the carbon footprint of selected oilseed crops grown onthe semiaridnorthernGreat Plainsand todetermine the effects of N fertilization and environments on the carbon footprint.
Materials and methods Five oilseed crops, Brassica napus canola, Brassica rapa canola, Brassica juncea canola, B. juncea mustard, and Sinapis alba mustard, were grown under the N rates of 0, 25, 50, 100, 150, 200, and 250 kg N ha−1 at eight environsites (location×year combinations) in Saskatchewan, Canada. Straw and root decomposition and various production inputs were used to calculate greenhouse gas emissions and carbon footprints.

Results and discussion Emissions from the production, transportation, storage, and delivery of N fertilizer to farm gates accounted for 42% of the total greenhouse gas emissions, and the direct and indirect emission from the application ofN fertilizerin oilseed productionadded another 31%tothetotalemission.EmissionsfromNfertilizationwere nine times theemission from the use of pesticides and 11 times that of farming operations. Straw and root decomposition emitted 120 kg CO2eq ha−1, contributing 10% to the total emission. Carbon footprint increased slightly as N rates increased from 0 to 50 kg N ha−1, but as N rates increased from 50 to 250 kg N ha−1, carbon footprint increased substantially for all five oilseed crops evaluated. Oilseeds grown at the humid Melfort site emitted 1,355 kg CO2eq ha−1, 30% greater than emissions at the drier sites of Scott and Swift Current. Oilseeds grown at Melfort had their carbon footprint of 0.52 kg CO2eq kg−1 of oilseed, 45% greater than that at Scott (0.45 kg CO2eq kg−1 of oilseed), and 25% greater than that at Swift Current (0.45 kg CO2eq kg−1 of oilseed).

Conclusions Carbon footprint of oilseeds was a function of the rate of N fertilizer, and the intensity of the functionality varied between environments. Key to lower carbon footprint in oilseeds is to improve N management practices.

Keywords Brassica juncea.Brassica napus.Carbon footprint.Environment.Greenhouse gas.Nitrogen management.NUE.Yellow mustard