Enhanced Efficiency Fertilizers in Maintaining Yield and Reducing Nitrogen Losses in Irrigated, Late-Sown Potatoes.

Field studies were conducted in 2015 and 2016 growing season at Northern Plains Potato Growers’ Association Irrigation site near Inkster, ND to evaluate the effectiveness of enhanced efficiency fertilizers (EEFs) in maintaining yield, quality and reducing environmental nitrogen (N) losses in irrigated potatoes (Solanum tuberosum). Two types of EEFs i.e. SuperU (urea with urease and nitrification inhibitor) and ESN (polymer coated urea); grower’s standard fertilization and un-amended urea were applied in three late-sown russet potato cultivars. Our findings suggested that yield responses vary widely with respect to years, length of growing season and cultivar type. Among EEFs, ESN consistently maintained yield compared to conventional fertilization practices. In shorter growing season (114 days), no yield benefit over N rate of 225 kg ha^-1 was obtained. Determinate cultivars can be a better choice to get good yield with lower N rate in shorter growing seasons. Both of the EEFs significantly reduced N losses through ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission compared to un-amended urea and grower’s standard fertilization practice. SuperU could not reduce nitrate (NO₃^-) leaching compared to un-amended urea while ESN did. Overall, ESN or polymer coated urea (PCU) is a promising choice for reducing N losses from irrigated potatoes.