Compare methods

	Food-System Life Cycle Assessment	Nitrogen Use Efficiency Analysis
Field	Food Agriculture Studies	Food Agriculture Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2018	2005
Originator	ISO 14040/14044 LCA framework; food-system synthesis by Joseph Poore & Thomas Nemecek	Jagdish K. Ladha and colleagues (synthesis of agronomic NUE indicators)
Type	Cradle-to-grave environmental modelling pipeline for foods and diets	Descriptive indicator pipeline for nitrogen-use efficiency
Seminal source	Poore, J., & Nemecek, T. (2018). Reducing food's environmental impacts through producers and consumers. Science, 360(6392), 987-992.	Ladha, J. K., Pathak, H., Krupnik, T. J., Six, J., & van Kessel, C. (2005). Efficiency of Fertilizer Nitrogen in Cereal Production: Retrospects and Prospects. Advances in Agronomy, 87, 85-156.
Aliases	Food LCA, Agri-food Life Cycle Assessment, Dietary Life Cycle Assessment, Cradle-to-Grave Food Footprinting	NUE Analysis, Nitrogen Use Efficiency, Fertilizer Nitrogen Efficiency Analysis, Nitrogen Recovery Efficiency Analysis
Related	4	4
Summary	Food-system life cycle assessment (LCA) quantifies the environmental footprint of a food, meal or diet across its entire life cycle — from agricultural inputs on the farm, through processing, packaging, transport, retail and cooking, to waste disposal. Following the ISO 14040/14044 framework, an analyst defines a functional unit (such as one kilogram of food, 100 grams of protein, or 1000 kilocalories), compiles a life-cycle inventory of all inputs and emissions at each stage, characterises those flows into impact indicators (greenhouse-gas emissions, land and water use, eutrophication and acidification), and interprets the result with sensitivity and uncertainty analysis. Poore and Nemecek's 2018 Science synthesis, covering tens of thousands of farms worldwide, showed that impacts vary as much as fifty-fold among producers of the same product and that even the lowest-impact animal foods typically exceed plant substitutes — establishing LCA as the central tool for comparing the sustainability of foods and diets.	Nitrogen use efficiency (NUE) analysis is the set of agronomic indicators used to quantify how effectively applied nitrogen is converted into harvested yield and nutrient uptake, and how much escapes to the environment. Synthesized authoritatively by Jagdish Ladha and colleagues in 2005, the family includes agronomic efficiency (extra yield per unit of nitrogen applied), recovery efficiency (the fraction of applied nitrogen the crop takes up), physiological efficiency (yield produced per unit of nitrogen taken up), partial factor productivity (total yield per unit of nitrogen applied), and the partial nutrient balance of nitrogen out in harvest versus nitrogen in from inputs. Because nitrogen is the most yield-limiting and environmentally costly nutrient in cereal systems, these indicators are central to diagnosing fertilizer performance, guiding the right rate, source, timing, and placement, and benchmarking the sustainability of cropping systems.