Two recent publications will be helpful for analysts who need to understand nutrient modeling in LCA.
Marieke ten Hoeve from the University of Copenhagen completed her doctoral thesis looking at the management of pig manure using LCA. Her final paper is "A life cycle perspective of slurry acidification strategies under different nitrogen regulations" (J Cleaner Production, 127:591-599). Acidification can substantially reduce the environmental impacts of manure.
Sara Heimersson has also completed her doctoral thesis and published "Life cycle inventory practices for major nitrogen, phosphorus and carbon flows in wastewater and sludge management systems" (Int J LCA, 8(1)1197-1212). The paper identifies variations in approach used in different LCA studies and calls for more complete LCAs and better motivated LCA methodological choices.