Intensifying wheat production increases bread yield with a minor increase in global warming potential: A life cycle assessment of Kansas wheat

There is a growing pressure to increase food production while reducing the negative environmental impact of farming. Here, we assessed management options to increase wheat and bread production and minimize negative environmental outcomes. Based on a survey of 656 commercial winter wheat fields, we identified four management levels that represented low, average, high, and top-yielding fields, and replicated these across 23 field experiments in Kansas, the largest wheat producer in the United States (US). Yield, residue, grain protein concentration, bread yield, and environmental outcomes were compared across the four management levels, including global warming potential (GWP) and energy balance quantified using seed-to-grain and seed-to-bread life cycle assessments (LCA). Grain yield and protein concentration increased with improved agronomic management, increasing bread yield. While energy use and GWP per unit area increased with management intensification, yield increases partially offset GWP and energy use per unit of grain and per unit of bread. Nitrogen and diesel were the primary drivers of GWP and energy input during the grain production phase, which accounted for 9-18% of the total bread footprint owing to larger contributions from transportation, milling, and baking. Uncertainties associated with nitrous oxide (N 2 O) emissions from N fertilization resulted in 6-17% variation in GWP estimates. Refining the current management of US wheat systems can help achieve the dual goal of increasing high-quality wheat production while minimizing environmental impact per unit of grain or bread.