Phosphorus loadings from the Maumee River watershed have significantly compromised the Lake Erie ecosystem, as evidenced by the most severe harmful algal bloom in Lake Erie in 2015 and the shut-down of Toledo drinking water supply in 2014. Despite government payments for adoption of voluntary conservation practices, excess nutrient runoff from agricultural production remains a substantial challenge. The right timing of nutrient application is a critical best management practice (BMP). Using a unique survey of 2540 farmer respondents in the Maumee River watershed, this paper analyzes how socio-psychological, socio-demographic, and field-based spatial characteristics impact farmers' adoption of timing-related best practices for nutrient management, including delaying broadcast application before a storm event, avoiding winter application of nutrients, and avoiding fall application of nutrients. Results reveal three unique classes of farmers for each of the timing-related management decisions. While the significance of most farmer and field characteristics varies across the three BMP adoption decisions, perceived efficacy—the belief that the particular practice will actually reduce dissolved phosphorus runoff from farm fields—is positively correlated with a higher likelihood of adopting each of the BMPs across almost all classes of farmers. For example, results from the ordered logit model suggest that a 20% increase in perceived efficacy would result in the likelihood of actual adoption of delaying broadcast from 35% to 48%. An implication is that policies and outreach efforts aimed at increasing farmers' perceived efficacy of practices could lead to higher adoption levels, but the effectiveness may vary across different classes of farmers.