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

Abstract

Purpose Best agricultural practices can be adopted to increase crop productivity and lower carbon footprint of grain products. The aims of this study were to provide a quantitative estimate of the carbon footprint of selected oilseed crops grown on the semiarid northern Great Plains and to determine 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 of N fertilizer in oilseed production added another 31% to the total emission. Emissions from N fertilization were nine times the emission from the use of pesticides and 11 times that of farming operations. Straw and root decomposition emitted 120 kg CO 2 eq 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 CO 2 eq 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 CO 2 eq kg −1 of oilseed, 45% greater than that at Scott (0.45 kg CO 2 eq kg −1 of oilseed), and 25% greater than that at Swift Current (0.45 kg CO 2 eq 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.

Lowering carbon footprint of winter wheat by improving management practices in North China Plain

“…In most cases, the higher nitrogen fertilizer application or irrigation rate, the greater GHG emissions per unit area during crop production (Gan et al, 2012b). Qin et al (2012) reported that nitrous oxide emissions were a linear function, and yield-scaled nitrous oxide emissions were a cubic function of the nitrogen fertilizer application rate.…”

“…Best management practices (BMP) have been developed for not only producing high-quality, affordable food in sufficient quantity, but also reducing negative environmental impacts (Gan et al, 2012b). To take advantage of these opportunities and promote the development of low-carbon agriculture, a study of total GHG emissions in the form of the carbon footprint of an agro-ecosystem is of critical importance (Yang et al, 2014).…”

“…Farm products in the near future may be valued based on their carbon footprint, with mandatory "carbon-labeling" of their carbon footprint. Policymakers, the general public, and producers urgently wish to know how farming practices could be improved to produce high-quality and affordable food in sufficient quantities while ensuring the products have a low carbon footprint (Gan et al, 2012b).…”

Less carbon emissions of wheat–maize intercropping under reduced tillage in arid areas

“…Also, cropping intensification is recognized as a key farming strategy in reducing global warming potential (Gan et al 2012). The adoption of intercropping has significant advantages on carbon sequestration than conventional sole cropping (Asgedom and Kebreab 2011;Gan et al 2011a). For example, maize-soybean (Glycine max L.) intercropping (Dyer et al 2012) and maize-wheat intercropping (Beedy et al 2010) enhance soil carbon sequestration and reduce carbon emission significantly compared to the corresponding monocultures.…”

Canola seed yield and phenological responses to plant density

“…When resources are limited or when the individuals are unevenly distributed within a low-density plant stand, interplant competition for available resources can be severe as the number and size of nearby plants increase (Baumann et al 2002). Canola plant performance is a function of available resources (Gan et al 2012). Individual plants in a low-density stand likely share a greater amount of resources such as light (Sunil et al 2013), water, and nutrients (Jamont et al 2013), than those within a high-density stand.…”