The implications of treating environmental pollution as an undesirable output (weak disposability) as well as a normal input (strong disposability) on the direct and indirect shadow price and cost estimates of nitrogen pollution abatement is analyzed using Nebraska agriculture sector data. The shadow price of nitrogen pollution abatement treated as an undesirable output represents the reduced revenue from reducing nitrogen pollution. In contrast, the shadow price of nitrogen pollution abatement treated as an input reflects the increased cost of reducing nitrogen pollution. For the 1936-97 period, the estimated shadow price and cost of nitrogen pollution abatement for Nebraska ranges from $0.91 to $2.21 per pound and from $300 to $729 million respectively.