Optimizing nitrogen management to enhance irrigated sugar beet yield and quality

Abstract

Sugar beet (Beta vulgaris L.) accounts for 55% of the total sugar production in the United States. Optimizing fertilizer nitrogen (N) management is pivotal for its economical and sustainable production and is challenging. Three-year field experiments (2020–2022) were conducted in western Nebraska to evaluate the effects of fertilizer N rates on beet root yield, sugar concentration, sugar loss to molasses (SLM), estimated recoverable sugar (ERS), and nitrogen use efficiency (NUE). Treatments included 0%, 50%, 80%, 100%, and 125% of recommended N based on the current University of Nebraska-Lincoln recommendation. Fertilizer application increased the root yield, ERS, and SLM but decreased sugar concentration in most cases compared to the control treatment. Beet NUE decreased with increasing total available N. Linear-plateau regression models fitted to root yield and ERS response curves showed that the agronomic optimum N rates (AONRs) were 179 and 166 kg N ha⁻¹ for root yield of 68.86 Mg ha⁻¹ and ERS of 11.95 Mg ha⁻¹, respectively. The findings showed that the root yield-based model required 35% less N rate than the current UNL beet N algorithm, and the ERS-based model required 13 kg N ha⁻¹ less N rate than the root yield-based model. Because of the trade-off effect of total available N on root yield and quality, the ERS-based N recommendation can be a potential strategy to optimize N management for economic and environmentally sustainable sugar beet production.