Nitrogen requirement of fodder and sugar beet (Beta vulgaris L.) cultivars under high-yielding conditions of northwestern Europe

ABSTRACT

This study provides current data on plant nitrogen (N) uptake required for maximum sugar yield (PNUp_max) and the corresponding fertilizer N dose (ND) (optimum N dose [ND_opt]) for high-yielding beet crops (sugar yield up to 20 Mg ha⁻¹). In 2010 and 2011, field experiments were conducted with four cultivars from Beta genus differing in dry matter composition, and six mineral NDs (0–200 kg N ha⁻¹) at three sites (The Netherlands, Germany, Denmark). Differences between cultivars in PNUp_max and ND_opt were small; however, environments (defined as combination of site and year) substantially differed from each other: highest PNUp_max and lowest ND_opt occurred at environments supplying high amounts of N from soil resources, and vice versa. The level of maximum sugar yield (SY_max) was related neither to PNUp_max (200–270 kg N ha⁻¹) nor to ND_opt. However, N dose and plant N uptake required for 95% of maximum sugar yield was 50–80 kg N ha⁻¹ lower than for maximum sugar yield. To conclude, accepting a slight reduction in sugar yield might allow for a substantial decrease in the ND. Cultivar choice and yield level need not to be taken into account at present.

KEYWORDS:

• Sugar yield
• N uptake
• N requirement
• fertilizer dose
• cultivar

Acknowledgements

We gratefully acknowledge the excellent technical work of the staff of our institutes IRS, IfZ and NBR in the field and lab. ‘Thank you’ to Dr. Christian Kluth for calculating the inverse polynomial functions. This work was conducted as a COBRI project (Coordination Beet Research International).

Disclosure statement

No potential conflict of interest was reported by the authors.