Performance of conventional and enhanced-efficiency nitrogen fertilizers on potato tuber mineral composition and marketability.

Background Potato is an essential crop for global food security, and its cultivation requires significant amount of readily available nitrogen (N) to ensure tuber quality. Therefore, managing N with enhanced-efficiency fertilizers becomes a potential strategy to meet the seasonal potato N demand. A 3 site-years (SYs) study was conducted to assess the marketable attributes and mineral composition of table-stock potato in response to N rates and fertilizers urea, ammonium sulfate, and ammonium sulfate nitrate (ASN) with nitrification inhibitor dimethylpyrazole phosphate (DMPP). Results At 75% of recommended N rate (RNR), ammonium sulfate and ASN + DMPP ensured marketable tuber yields equivalent to that observed at 100% of RNR. Urea promoted greater tuber K and Mg concentrations than ammonium sulfate and ASN + DMPP. Although inconsistent across SYs, ASN + DMPP generally reduced starch and reducing sugars contents and increased pulp pH and protein content than other fertilizers. Increasing N rates from 50% up to 75 and 100% of RNR increased marketable tuber yields and protein content, while soluble solids increased from 50 to 100% of RNR. Conversely, increasing N rates from zero to 75% of RNR reduced tuber firmness, while N application reduced tuber P concentration, regardless of N rates. Conclusion While ASN + DMPP showed potential for increasing marketable tuber yield and protein content, potatoes receiving ammonium sulfate and ASN + DMPP lowered tuber K and Mg concentrations compared to those receiving urea. Overall, potato tuber quality improvements are N source-specific, demanding strategies under which these fertilizers can ensure/improve tuber nutritional composition along with size quality. This article is protected by copyright. All rights reserved.