Can foliar urea reduce nitrogen losses from potato production in Atlantic Canada?

In recent years it has become increasingly popular for potato producers in Atlantic Canada to include urea in the foliar applications of fungicides. Producers believe this practice sustains their potato crop through periods of water stress and allows for more rapid recovery following a precipitation event. This urea application is not considered as part of their nitrogen (N) fertility program and is added in addition to the recommended rates of N fertilizer at planting. This project examines the potential to reduce the amount of N fertilizer added at planting in situations where foliar urea will be applied to the crop. We are evaluating whether in-season foliar urea (Right Product, Right Time and Right Place) in combination with reduced N fertilizer rates (Right Rate) at planting is an effective best management practice (BMP) for sustaining potato yields and reducing nitrous oxide emissions and nitrate leaching.

The experiment, established in 2013, was conducted for a second year in 2014 evaluating the use of foliar urea to increase N use efficiency in potato production in Atlantic Canada. The treatments included five rates of N fertilizer application at planting (0, 120, 150, 180, 240 kg N/ha) as well as addition of 30 kg N/ha of foliar applied urea on the 120 and 150 kg N/ha treatments. Plant yield response, greenhouse gas emissions, soil nitrate concentration and nitrate flux (ion exchange membranes) were measured during the growing season.

In 2014, preliminary data suggest that rates of N fertilizer above 150 kg N/ha did not result in an increased potato yield. The application of foliar urea to the 120 and 150 kg N/ha treatments did not increase potato yield. Increased rates of N fertilization did however result in higher soil nitrate concentration and flux. The application of foliar urea did not increase soil nitrate concentration or flux.