Comparison of nitrogen recommendation strategies in northwest U.S. sugarbeet production

Authors: OLSEN, DAVEY - Amalgamated Sugar Company; Tarkalson, David; Bjorneberg, David - Dave

Submitted to: Journal of Sugar Beet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2023
Publication Date: 2/24/2023
Citation: Olsen, D., Tarkalson, D.D., Bjorneberg, D.L. 2023. Comparison of nitrogen recommendation strategies in northwest U.S. sugarbeet production. Journal of Sugar Beet Research. 60:1:4-10.

Interpretive Summary: Nitrogen (N) management is the most important fertility consideration in sugarbeet production as it affects not only yield but also sugar and sugar quality. As industry yields continue to increase over time, the established method for determining N requirement in sugarbeets results in greater and greater fertilizer N applied. This is despite research showing that the actual amount of N supply required to achieve these yields has remained relatively stable over time. This study was conducted to compare two commonly used N determination methodologies to a potential alternative N management approaches in the Northwest U.S. sugarbeet production. In 2020 and 2021, studies were conducted in 6 locations by The Amalgamated Sugar Company (ASCO) to evaluate current and proposed N supply recommendations on sugarbeet production. The N supply treatments were determined using the industry standard yield goal N management (YGNM) method, recommendations from a commonly used agricultural consultant business (ACB), and 3 rates representing a range of a proposed alternative to the YGNM approach, Static Range N Management (SRNM) low, SRNM med, and SRNM high. For 5 of the 6 research sites the SRNM low N supply treatment met or was closest to the N supply required to maximize yields. For the sixth site-year, the SRNM med N supply treatment maximized yield. Nitrogen requirement calculated using the YGNM approach, resulted in an average of 91 kg N/ha in excess fertilizer N being applied. This represented an economic cost of between $79 to $200/ha depending on N price. The ACB recommendations resulted in even greater excess N fertilizer application, an average of 140 kg N/ha, costing from $122 to $308/ha depending on N price. The SRNM approach better matches N supply with crop need compared to the YGNM and Soil Lab N recommendations over time. Sugarbeet growers should evaluate the needed N supplies in their growing area and follow a SRNM approach.

Technical Abstract: Nitrogen (N) management is the most important fertility consideration in sugarbeet (Beta vulgaris) production as it affects not only yield but also sugar and sugar quality. As industry yields continue to increase over time, the established method for determining N requirement in sugarbeets results in greater and greater fertilizer N applied. This is despite research showing that the actual amount of N supply required to achieve these yields has remained relatively stable over time. This study was conducted to compare two commonly used N determination methodologies to a potential alternative N management approaches in the Northwest U.S. sugarbeet production. In 2020 and 2021, studies were conducted in 6 locations by The Amalgamated Sugar Company (ASCO) to evaluate current and proposed N supply recommendations on sugarbeet production. The N supply treatments were determined using the industry standard yield goal N management (YGNM) method, recommendations from a commonly used agricultural consultant business (ACB), and 3 rates representing a range of a proposed alternative to the YGNM approach, Static Range N Management (SRNM) low, SRNM med, and SRNM high. Two of the study sites had significant treatment effects on root and sucrose yield. The N supply needed to maximize sucrose yields at the 2 responsive sites was 202 and 218 kg N/ha. For 5 of the 6 site-years, the SRNM low N supply treatment met or was closest to the N supply required to maximize yields. For the sixth site-year, the SRNM med N supply treatment maximized yield. Nitrogen requirement calculated using the YGNM approach, resulted in an average of 91 kg N/ha in excess fertilizer N being applied. This represented an economic cost of between $79 to $200/ha depending on N price. The ACB recommendations resulted in even greater excess N fertilizer application, an average of 140 kg N/ha, costing from $122 to $308/ha depending on N price. The SRNM approach better matches N supply with crop need compared to the YGNM and Soil Lab N recommendations over time. Sugarbeet growers should evaluate the needed N supplies in their growing area and follow a SRNM approach.