You're making a mountain out of a mole hill and you're also straying from the original poster's question. I'm tryign to understand how you use this method. Let's go back to my first question: How do you use ENR in a route based system? You said that you "take into account all potential nitrogen (and nutrient) inputs, including ENR, in order to develop as best a management plan as possible." 1) Do you take into account what customers return clippings and what customers bag them? Do you treat customers differently based on returning or removing clippings? What if a customer bags one time, then returns clippings another time? 2) What target N budget number do you use? I'm assuming you begin with a total yearly N amount you think the plant needs to produce the conditions you desire, then subtract other N sources to determine how much fert you should apply. For what coverage area do you do this (each individual customer, each route, each ZIP, each city, each county, each neighborhood)? 3) I'm not sure that not accounting for ENR in the manner you describe is poor stewardship. Since you applied an estimate to a broad area, you risk underapplying to some areas and overapplying to others. Underapplying can lead to thin turf stands, which are not beneficial to the enivronment. Overapplying can lead to nutrient loss, which may not be beneficial to the environment. It seems to me that if you're going ot point to ENR as a way to be a good enviro steward, you would have to use it site by site, or its no better than anyone else's guess.