Nitrogen abatement cost comparison for cropping systems under alternative management choices

There is a need for cost-effective methods to reduce nitrogen pollution from agriculture. Marginal abatement cost (MAC) curves for nitrate-nitrogen pollution in an agricultural watershed are evaluated using estimated crop yield and nitrate pollution production functions for alternative cropping systems. The cropping systems considered in this study included i) two grain corn-based cropping systems; ii) two potato-based cropping systems; and iii) a vegetable-horticulture system, managed under conventional tillage (CT) and no-till (NT). The cost-effective potato-based cropping system which met the Health Canada maximum contaminant limit (MCL) for nitrate-N, with the highest gross margin ($6973 ha-1) and lowest abatement cost ($395 ha-1) was a potato-barley-winter wheat-potato-corn rotation under no-till (PBWPC-NT). Similarly, among the vegetable-horticulture cropping systems, potato-winter wheat-carrot-corn rotation under CT (PWRC-CT) generated the highest gross margin and lowest on-farm abatement cost ($680 ha-1). As the Health Canada allowable limit on nitrate-N pollution was relaxed (i.e., less stringent), the cost-effective corn-based cropping system shifted from a rotation involving corn-corn-alfalfa-alfalfa-alfalfa under CT to corn-corn-corn-alfalfa-alfalfa under NT.