Carbon footprints for wheat cropping systems in semiarid prairies
Wheat is the world's most favored cereal food source, second to rice. However, the production of wheat crop is often considered to be environmentally-unfriendly, because of the large inputs of fuel, inorganic fertilizer, and pesticides, and these inputs are known to be a major source of greenhouse gases that contribute negatively to climate change. We do not know whether adopting new and improved farming practices for wheat production can increase crop productivity while concurrently reducing overall carbon emissions. In this study, we quantified the carbon footprint of alternative wheat production systems suited to the semiarid Canadian prairie. Data from a 25-year (1985-2009) field experiment conducted in southwestern Saskatchewan were analyzed. We found that wheat that was fertilized with 20 to 48 kg N ha-1 (based on soil tests) produced grain yields of 980 to 2460 kg N ha-1 annually (depending upon weather conditions). Wheat produced with improved farming practices had a negative (or favorable) carbon footprint, averaging -256 kg CO2 equivalents ha-1 or -0.146 kg CO2 equivalents kg-1 of grain yield. Wheat produced in a lentil-wheat rotation had the highest carbon footprint value at -0.370 kg CO2 equivalents per kg of grain yield. On average, for each kg of wheat grain produced a net 0.018 to 0.370 kg CO2 equivalent was sequestrated from the atmosphere into the soil. Our study show that with improved farming practices wheat crops grown on the semiarid Canadian prairie can convert more CO2 from the atmosphere than is actually emitted during its production.
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