Does crop rotation with legumes provide an efficient means to reduce nutrient loads and GHG emissions?

We investigate crop rotation with legumes from economic and environmental perspectives by asking how effective they are at providing profits and reducing nutrient runoff and greenhouse gas emissions compared with monoculture cultivation. We study this effectiveness in three alternative policy regimes: the free market optimum, the Finnish agri-environmental scheme, and socially optimal cultivation, and also design policy instruments to achieve the socially optimal outcomes in land use and fertilization. We first develop an analytical model to describe crop rotation and the role of legumes, and examine its implications for water and climate policies. Drawing on Finnish agricultural data, we then use numerical simulations and show that shifting from monoculture cultivation to crop rotation with legumes provides economically and environmentally better outcomes. Crop rotation with legumes also reduces the variability in profits caused by stochastic weather. The optimal instruments implementing the social optimum depend on nutrient and climate damage (nitrogen tax), as well as carbon sequestration and nutrient reduction benefits (buffer strip subsidy).