Irrigated Potato (Solanum tuberosum) Yield and Nitrogen Losses As Influenced By Fertilizer Management and Cultivars.

Increasing demand for food supply and concerns about environmental and soil health created a compulsion for sustainable management for the most limiting and loss prone nutrient, nitrogen (N). Enhanced efficiency fertilizers (EEFs) are believed to have a potential to reduce nutrient loss and environmental impact while maintaining or increasing yield. A field study will be conducted to evaluate if EEFs (SuperU and ESN) and split application can reduce N losses with profitable yield compared to conventional fertilization practices in three potato cultivars at Northern Plains Potato Growers’ Association Irrigation site near Inkster, ND in 2016. The experiment will be laid out with eighteen treatment combinations comprised of six N treatments [Growers’ standard, Urea @ 200 lb N/acre, UreaSplit @ 250 lb N/acre, ESN @ 250 lb N/ acre, SuperU@ 250 lb N/ acre and Control (no fertilizer N)] and three cultivars [Russet Burbank, Dakota Trailblazer, ND8068-5 Russ] in factorial RCBD with four replications. Losses of N through ammonia (NH₃) volatilization, nitrous oxide (N₂O) emission and nitrate (NO₃^-) leaching will be measured throughout the growing season. After harvest, tuber yield and quality, above ground biomass and plant N uptake will be determined. The exact same experiment conducted in 2015 showed that higher N application rate i.e. above 200 lb N/acre and split application did not significantly increase tuber yield. Considering N loss mitigation, ESN @ 250 lb N/acre reduced N loss through NH₃ volatilization and NO₃^- leaching compared to other N treatments as well as increased yield significantly over the control and conventional practices in all varieties. SuperU @ 250 lb N/acre reduced N₂O emission significantly, but increased NO₃^- leaching and NH₃ volatilization enormously and failed to increase yield significantly compared to control. The combined results from 2015 and 2016 will strongly validate the outcomes of the experiment. Comprehensively this study focusses on the efficiency of N source, timing and cultivars of Potato on target yield achievement.