[a] 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.
[b] Inorganic fertilizer applied to corn land is reduced by 100 kg N ha‐1 to fully utilize the applied manure nitrogen.
[c] Same as [b] plus an annual rye cover crop is planted after corn harvest and killed in the spring before planting.
[d] Same as [c] plus manure is loaded each day to the top of the storage preventing a surface crust from forming.
[e] Same as [d] plus farm land is switched from a clay loam soil (45% clay, 45% silt, 10% sand) to a loam soil (10% clay, 70% silt, 20% sand).
[f] Total CO2‐equivalent greenhouse gas emission considering the global warming potential of CH4 and N2O to be 25 and 298 times that of CO2, respectively.