| Summary: | Applying higher nitrogen (N) rates than required for optimum potato (<i>Solanum tuberosum</i> L.) growth leads to economic and environmental losses. The extent to which the N rate associated with maximum potato yields differs from that maximizing net revenue (NR) or potato specific gravity is not fully understood. The objectives of this three-year study (2013–2015) conducted at five sites in three Canadian provinces (MB-1; MB-2; QC-1; QC-2; PEI) (15 site-years) were to: (i) assess potato marketable yield, NR, and specific gravity responses to increasing N application; (ii) calculate the N rate maximizing marketable (N<sub>max</sub>) yield and NR using different statistical models. The year, N fertilizer, and their interaction were significant on marketable yield and NR except at the MB-1 site where no significant effect of N was observed. No significant yield increases were observed at a N rate above 60 kg N ha<sup>−1</sup> at four site-years and above 120 kg N ha<sup>−1</sup> at five site-years, implying that the current recommended N rate could be reduced. All models fitted the marketable and NR data equally based on R<sup>2</sup>, mean bias error or root mean square error and resulted in comparable predicted yield and NR values. However, N<sub>max</sub> values were different depending on the model with higher values being predicted by the quadratic- (161.4 to 191.9 kg N ha<sup>−1</sup>) and the quadratic plateau models (60 to 191.9 kg N ha<sup>−1</sup>), while lower N<sub>max</sub> values were obtained with linear plateau- (60.6 to 129.8 kg N ha<sup>−1</sup>) and Mitscherlich–Baule plateau models (60.9 to 130. 9 kg N ha<sup>−1</sup>). Nitrogen rate maximizing NR was on average 4% lower than the N rate maximizing marketable yields, except at one site where it was higher by 26 kg N ha<sup>−1</sup> when the quadratic plus plateau model was used. Specific gravity tended to decrease with the N rate. Our study confirms trade-offs between the N rate maximizing yields or NR with that maximizing specific gravity. Nitrogen rate maximizing marketable yield and NR varies depending on the selected model.
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