Abstract

The 4Rs of nutrient management is a global agronomic initiative with an aim to improve the sustainability of major cropping systems and the environment. The objective for this project is to evaluate individual and stacked 4R management practices and how they intersect. A field trial near Grace, Idaho was conducted on potato (Solanum tuberosum L.) in 2020 and 2023. Nitrogen (N) fertilizer treatments included all combinations of two sources [urea or polymer coated urea (PCU)], two rates (82 or 100% of the recommended rate), and/or two timing/placements (all applied at emergence or 84% at emergence + 16% fertigation simulation) compared to an untreated control. Overall, potato was responsive to N for petiole nitrate (NO3-N), Normalized Difference Vegetative Index (NDVI), and US No. 1 and marketable tuber yield. There were large numerical yield increases for most treatments compared to the unfertilized control in both years (2.2-8.2 Mg ha-1), though statistical significance for multiple yield classes was only reached in 2023. Treatments with PCU had a significant increase in US No. 1, US No. 2, and marketable yield over urea. The split application timing resulted in larger tubers and less cull yield in 2020 with little impact on yield and quality in 2023. The reduced rate negatively impacted US No. 1 and marketable yield while increasing cull yield, though not when applied as PCU. This data reinforces the 4R principles and suggests that stacking some methods may not be necessary.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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