100 Holstein cows producing 9,000 kg per cow of milk plus 80 replacement heifers housed year round in free‐stall barns with feed produced from 50 ha of corn, 20
ha of perennial grassland, and 20 ha of alfalfa. Inorganic nitrogen fertilizer is applied to corn land ignoring manure nutrients, which adds an additional 100 kg N
ha‐1 of corn