The relationship of nutrient management strategies to optimal dairy herd size and net farm return was simulated with a linear programming model. A generalized dairy farm model was constructed with two different corn and alfalfa crop sequences, high efficiency (0.5×total N) or low efficiency (0.2×total N) manure N use, and available N either restricted to that usable by the corn crop or unrestricted. Nutrient management strategies constrained optimal herd size and net farm return when manure N was used efficiently and available N was restricted to that required by the crops. Manure application to third-year alfalfa or a corn grain purchasing activity and relaxed constraints on soil test P and K levels resulted in increased optimal herd size, and consequently increased net farm return as compared to the restricted conditions. The increased scope of inquiry from nutrient management for farm components to those for whole farm made possible the description of emergent properties of the simulated dairy farm. These properties suggest that research efforts and policy decisions concerning nutrient management strategies cannot consider only research results or enterprises in isolation from the other components of the entire farm.
