Potato Yield Response and Nitrogen Losses As Influenced By Nitrogen Management and Cultivar.

Potato is a nitrogen (N) intensive crop that requires adequate N fertilization to achieve target yield and quality. The applied N through inorganic fertilizers is prone to losses through leaching, volatilization and denitrification when grown in coarse soils with irrigation. Groundwater contamination and unaccepted N levels in drinking water due to nitrate (NO3-) leaching and greenhouse gas nitrous oxide (N2O) emission due to denitrification are much debated environmental issues related to potato N fertilization. Alternative N fertilizers (polymer coated or fertilizers blended with nitrification inhibitor and/or urease inhibitor) have been developed to minimize N losses from soil and increase nitrogen use efficiency of crops. A study on three irrigated potato cultivars (Russet Burbank, Dakota Trailblazer and ND8068-5 Russ) will be conducted at the Northern Plains Potato Growers Association irrigation site near Inkster, North Dakota in 2015 growing season to evaluate the efficiency of slow release N fertilizers (ESN and Super U) and split application of N fertilizers to minimize N loss from soil over standard growers’ practice and pre-plant urea application. Nitrogen budget and N recovery % for three potato cultivars and each N treatment will be calculated using the ammonia volatilization, N2O emission, NO3- loss below root zone and residual available soil N data. Yield responses and petiole N concentration during tuber initiation of three potato cultivars against the N fertilizer treatments will also be examined to establish the best way to optimize irrigated potato yield with minimization of N loss. Comprehensively this study will focus on efficiency of N source, timing and cultivars of a specific crop (Potato) on target yield achievement utilizing sustainable N fertilization practices. Key words: Potato, Volatilization, N2O emission, Leaching, Split application, Slow release N fertilizer.