Does growing grain legumes or applying lime cost effectively lower greenhouse gas emissions from wheat production in a semi-arid climate?

Abstract

a b s t r a c tAgriculture production contributes to global warming directly via the release of carbon dioxide (CO 2 ), methane and nitrous oxide emissions, and indirectly through the consumption of inputs such as fertilizer, fuel and herbicides. We investigated if including a grain legume (Lupinus angustifolius) in a cropping rotation, and/or applying agricultural lime to increase the pH of an acidic soil, decreased greenhouse gas (GHG) emissions from wheat production in a semi-arid environment by conducting a streamlined life cycle assessment analysis that utilized in situ GHG emission measurements, rather than international default values. We also assessed the economic viability of each GHG mitigation strategy. Incorporating a grain legume in a two year cropping rotation decreased GHG emissions from wheat production by 56% on a per hectare basis, and 35% on a per tonne of wheat basis, primarily by lowering nitrogen fertilizer inputs. However, a large incentive ($93 per tonne of carbon dioxide equivalents reduced) was required for the inclusion of grain legumes to be financially attractive. Applying lime was profitable but increased GHG emissions by varying amounts depending upon whether the lime was assumed to dissolve over one, five or 10 years. We recommend further investigating the impact of liming on both CO 2 and non-CO 2 emissions to accurately account for its effect on GHG emissions from agricultural production.

Improving pulse crops as a source of protein, starch and micronutrients

“…Lower fertiliser application also reduces greenhouse gas emissions and the pollution of natural environments through nitrogen runoff into water courses (Barton et al . ; Foyer et al . ).…”

An international comparison of agricultural nitrous oxide emissions

“…There are several studies that have examined how carbon footprints can be reduced from cropping systems, such as: (1) including legume crops in the farming system to reduce both N 2 O and soil carbon emissions (Paul et al, 2002;Barton et al, 2014); (2) diversification of crop rotation to reduce overall carbon footprints (Yang et al, 2014); (3) keeping crop residue and application of manure on farms to increase soil carbon levels (Peterson et al, 2013;Knudsen et al, 2014;Mukul et al, 2016); (4) application of biochar into soil to reduce nutrient leaching and N 2 O emissions (Pudasaini et al, 2012); and (4) maintaining soil moisture levels below certain percentage to reduce the amount of direct and indirect N 2 O emissions (Castanheira and Freire, 2013). However, these are outside the scope of this paper and their impacts are, therefore, not considered.…”

“…Among the synthetic fertilisers, nitrogen (N) fertilisers are major contributors of global emissions as they, during nitrification and denitrification processes, produce N 2 O which has 298 times greater global warming potential than carbon dioxide (CO 2 ;IPCC, 2007;Yan et al, 2015). Until the early 1900s, legume-based rotational cropping systems were very popular for fixing N and making it available to subsequent nonleguminous crops (Barton et al, 2014). As a result, the use of Nfertiliser and related GHG emissions were lower.…”

Strigolactones positively regulate chilling tolerance in pea and in Arabidopsis

“…Legumes are essential for future food security, because they are central components of sustainable agriculture and key protein sources in human and animal diets (Barton, Thamo, Engelbrecht, & Biswas, ; Graham & Vance, ). However, the genetic improvement of legumes has lagged behind that of cereal crops (Foyer et al, ).…”