Carbon footprint of spring barley in relation to preceding oilseeds and N fertilization

PurposeCarbon footprint of field crops can be lowered through improved cropping practices. The objective of this study was to determine the carbon footprint of spring barley (Hordeum vulgare L.) in relation to various preceding oilseed crops that were fertilized at various rates of inorganic N the previous years. System boundary was from cradle-to-farm gate.Materials and methodsCanola-quality mustard (Brassica juncea L.), canola (Brassica napus L.), sunflower (Helianthus annuus L.), and flax (Linum usitatissimum L.) were grown under the N fertilizer rates of 10, 30, 70, 90, 110, 150, and 200 kg N ha−1 the previous year, and spring barley was grown on the field of standing oilseed stubble the following year. The study was conducted at six environmental sites; they were at Indian Head in 2005, 2006 and 2007, and at Swift Current in 2004, 2005 and 2006, Saskatchewan, Canada.Results and discussionOn average, barley grown at humid Indian Head emitted greenhouse gases (GHGs) of 1,003 kg CO2eq ha−1, or 53% greater than that at the drier Swift Current site. Production and delivery of fertilizer N to farm gate accounted for 26% of the total GHG emissions, followed by direct and indirect emissions of 28% due to the application of N fertilizers to barley crop. Emissions due to N fertilization were 26.6 times the emission from the use of phosphorous, 5.2 times the emission from pesticides, and 4.2 times the emission from various farming operations. Decomposition of crop residues contributed emissions of 173 kg CO2eq ha−1, or 19% of the total emission. Indian Head-produced barley had significantly greater grain yield, resulting in about 11% lower carbon footprint than Swift Current-produced barley (0.28 vs. 0.32 kg CO2eq kg−1 of grain). Emissions in the barley production was a linear function of the rate of fertilizer N applied to the previous oilseed crops due to increased emissions from crop residue decomposition coupled with higher residual soil mineral N.ConclusionsThe key to lower the carbon footprint of barley is to increase grain yield, make a wise choice of crop types, reduce N inputs to crops grown in the previous and current growing seasons, and improved N use efficiency.

[1]  Y. Gan,et al.  Adaptation of oilseed crops across Saskatchewan , 2010 .

[2]  Devon E. Worth,et al.  Estimation of N2O emissions from agricultural soils in Canada. I. Development of a country-specific methodology , 2008 .

[3]  C. Campbell,et al.  Carbon input to soil from oilseed and pulse crops on the Canadian prairies , 2009 .

[4]  Engin Özgöz,et al.  Assessment of spatial variability in penetration resistance as related to some soil physical properties of two fluvents in Turkey , 2004 .

[5]  D. Flaten,et al.  Nitrogen and sulphur fertilizer management for growing canola on sulphur sufficient soils , 2007 .

[6]  J. Krupinsky,et al.  Managing Plant Disease Risk in Diversified Cropping Systems , 2002 .

[7]  Matthew Saunders,et al.  Key questions and uncertainties associated with the assessment of the cropland greenhouse gas balance , 2010 .

[8]  Donald L. Tanaka,et al.  Soil Water Depletion and Recharge under Ten Crop Species and Applications to the Principles of Dynamic Cropping Systems , 2007 .

[9]  R. Littell.  SAS System for Mixed Models , 1996 .

[10]  J. O'donovan,et al.  Tillage and Nitrogen Influence Weed Population Dynamics in Barley (Hordeum vulgare) , 1997, Weed Technology.

[11]  R. Desjardins,et al.  The impact of increased biodiesel production on the greenhouse gas emissions from field crops in Canada , 2010 .

[12]  S. Malhi,et al.  Interactive effects of N and S fertilizers on canola yield and seed quality on s-deficient gray luvisol soils in northeastern Saskatchewan , 2007 .

[13]  Corinne Le Quéré,et al.  Climate Change 2013: The Physical Science Basis , 2013 .

[14]  Keith A. Smith,et al.  Climate‐ and crop‐responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer use , 2005 .

[15]  C. Liang,et al.  Carbon footprint of canola and mustard is a function of the rate of N fertilizer , 2011, The International Journal of Life Cycle Assessment.

[16]  J. Minx,et al.  Allocating ecological footprints to final consumption categories with input-output analysis , 2006 .

[17]  Brian McConkey,et al.  Lowering carbon footprint of durum wheat by diversifying cropping systems , 2011 .

[18]  R. Zentner,et al.  Comparative nitrogen response and economic evaluation for optimum yield of hybrid and open-pollinated canola , 2007 .

[19]  B. McConkey,et al.  Fertilizer N response and canola yield in the semiarid Canadian prairies , 2009 .

[20]  G. Velthof,et al.  Towards an agronomic assessment of N2O emissions: a case study for arable crops , 2010 .

[21]  P. Rochette,et al.  Greenhouse gas contributions of agricultural soils and potential mitigation practices in Eastern Canada , 2005 .

[22]  Yantai Gan,et al.  Strategies for reducing the carbon footprint of field crops for semiarid areas. A review , 2011, Agronomy for Sustainable Development.

[23]  R. Betts,et al.  Changes in Atmospheric Constituents and in Radiative Forcing. Chapter 2 , 2007 .

[24]  P. Miller,et al.  In Search of a Sustainable Cropping System for the Semiarid Canadian Prairies , 2001 .

[25]  S. Malhi,et al.  Seeding rate, fertilizer level and disease management effects on hybrid versus open pollinated canola (Brassica napus L.) , 2007 .

[26]  Ward N. Smith,et al.  A proposed approach to estimate and reduce net greenhouse gas emissions from whole farms , 2006 .

[27]  R. Lal,et al.  Carbon emission from farm operations. , 2004, Environment international.