The sugar beet has highest nutrient demands
Sugar beets are mainly grown for the production of pure sugar. In the future, sugar beets may increasingly be used as a renewable energy source in the production of bioethanol and biogas or in the production of plastic substitutes. The continued production of this important commodity requires advanced crop management techniques, and the economical as well as ecological use of any input materials.
Within a crop rotation, sugar beet has the greatest demand on the supply of nutrients. Here, not only the main nutrients such as nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and sulphur (S) are very important but also trace minerals such as boron (B) and manganese (Mn).
There are many benefits to the farmer for growing sugar beet. The broad-leaved crop provides a useful break in intensive cereal rotations, increases soil fertility and complements wide-ranging soil cultivation methods.
Potassium – the foundation for a reliable yield in sugar beet
- With an uptake of 450-600kg K2O ha-1 more potassium is taken up by the sugar beet crop than any other nutrient.
- The largest proportion of potassium can be found in the physiologically active green foliage. The potassium content of the storage organ, the beet, is much lower.
- Potassium is known for its positive effect on yield and sugar content.
- Potassium increases photosynthetic output which in turn results in increased carbohydrate metabolism (sugar synthesis). In addition, potassium is vital for the efficient transport of photosynthetic products and their subsequent deposition in the storage organ (the beet).
- Potassium increases the crops’ resistance to pests thereby allowing healthy crop development to proceed.
- Low potassium concentration in the soil jeopardizes soil fertility and will negatively affect yield and sugar content.
Numerous results gained from extensive field trials have demonstrated the significant effect of potassium fertilisation on yield of sugar beet – even where potassium concentrations in the soil appear to be adequate.
Potassium for improved quality in sugar beet
- The most important factor for quality is sugar content. Potassium positively effects sugar content because of its specific physiological effects on synthesis, transport and storage of sugars.
- In trials, the supply of an optimum quantity of potassium resulted in an increased sugar content of between 0.5 and 1% and, therefore, the value of the beet crop was higher.
- Both potassium and sodium (Na) influence the pH of the raw sugar extract where alkalinity must be minimised for the efficient extraction of sugars.
- In several regions, an additional quality payment is set using the standard molasses loss (SMV). This SMV value is affected through fertilisation mainly via the content of α-amino-nitrogen which is undesirable in sugar beet.
- After the introduction of the formula for calculating sugar beet quality based on potential sugar extraction, potassium fertilisation has only a negligible effect on the standard molasses loss; this is because small increases in potassium content of beets are overcompensated via a decreasing α-amino-nitrogen-content. Therefore, the standard molasses loss remains mainly unchanged.
- An optimum potassium supply improves the efficiency for nitrogen in sugar beet.
High sugar yield through balanced nutrition
To ensure a high sugar yield, the sugar beet crop requires – in addition to nitrogen, phosphorus and potassium – a good supply of the nutrients magnesium, sodium, sulphur, boron and manganese in a balanced ratio.
- Magnesium has two main positive effects on yield. First magnesium helps to maintain the healthy green canopy enabling more sugar to be produced for a longer period of time. Secondly magnesium is crucial in the citric acid cycle (important for cell respiration) where the synthesis of proteins, fats and carbohydrates can be optimised.
- A sufficient supply of sodium improves water use efficiency and can partly offset potassium deficiency during dry periods. Trial results show an increase in yield of 300-600kg sugar ha-1 when 20-40kg sodium ha-1 were applied.
- An adequate supply of sulphur improves sugar quality by decreasing α-amino-N-content. Sulphur deficiency increases standard molasses loss.
- Boron is important for cell development and for production of components such as sugar. Boron deficiency results in heart and dry rot and therefore in substantial yield losses.
- Manganese has similar functions in the metabolism as magnesium. It positively influences yield, for example by improving assimilation by the leaves during the growing period.
Fertiliser recommendations for sugar beet
Fertiliser is applied in order to maintain the fertility of the soil so that its natural yield potential can be protected over the long term. This requires the maintenance of an optimal nutrient content in the soil. Nutrients removed with the harvest have to be replaced through an adequate application of fertiliser. Together with the replacement of removed nutrients adjustments have to be added for site specific losses (for example: leaching or erosion).
The total removal of a plant results from the nutrient uptake of the main crop (e.g. grain, tubers or beets) and the uptake of harvest residues (e.g. straw, leaves). If the harvest residues remain on the field, only the removed nutrients by the main crops have to be replaced.
Recommendations for soil applications
|Total removal (incl. harvest residues)||Removal through main crop||Fertiliser recommendation due to nutrient uptake|
with optimal nutrient soil content class (per hectare)
|Total removal of||Through main crop|
K2O / MgO / SO3
K2O / MgO / SO3
(at a yield level of 65t)
|460 / 100 / 50||160 / 50 / 25||1150kg Korn-Kali®||400kg ESTA® Kieserit||400kg Korn-Kali®||200kg ESTA® Kieserit|
Recommendations for foliar applications
Video on the nutrient supply of sugar beet
Nutrient Supply of Sugar Beet – Greater Yields and Optimal Quality in Sustainable Sugar Beet Cultivation
The sustainable production of the high-grade sugar beet – whether for quota sugar, industrial sugar, bio ethanol or biogas – requires adequate and balanced nutrient supply to the plant. In sugar beet cultivation, the nutrient potassium (K) is well known for its positive effects on yield formation and sugar content. But the primary nutrients nitrogen (N), phosphorous (P), magnesium (Mg), lime, sodium (Na) and sulphur (S) as well as the trace minerals boron and manganese are also indispensable for optimising yield and quality in sugar beet cultivation.
Watch and listen what our expert consultant has to say on the formation of top-grade sugar beet and yields.