The queen of crops, that's what the sugar beet is also called. Being "sweet", however, is not the only feature. The development of its use played a major part in the agro-industrial revolution of the past, more than 200 years ago. Now, the sugar beet is back in the game when it comes to new technologies involving the use of sugar molecules: as energy storage, in bioreactors, or in building materials for anything the 3D printer can create.
The sugar beet has the highest nutrient requirements
With this perspective for the future, the crop is still an important crop rotation element in the important arable regions of Germany. Within the crop rotation, sugar beet places the highest demands on the supply of macro- and micronutrients.
- Potassium is a prerequisite for high, reliable yields, and is important for optimum nitrogen efficiency.
- Magnesium maintains the assimilation performance of the leaves and the build-up of important plant constituents.
- High sugar yields are achieved through balanced nutrient supply.
- Heavy losses are likely in the event of boron deficiency.
The sugar beet is a supplier of valuable sugar and bioenergy
Sugar beet is primarily cultivated for sugar production. There are also other developments in the bioenergy sector, such as ethanol, biogas and bioplastics, which may provide potential for new uses of sugar beet in the future. Sustainable production of the high-quality raw material sugar beet requires sophisticated cultivation technology and the economically and ecologically optimal use of operating resources.
The most important nutrients for sugar beet
Potassium – the prerequisite for high sugar beet yields
- With a potassium uptake of 450-600 kg/ha K2O, potassium is the most important nutrient in sugar beet cultivation in terms of quantity.
- The larger amounts of potassium are found in the physiologically active green leaf mass, while the potassium content in the storage organ, the beet, is significantly lower.
- Potassium is known for its positive effects on yield formation and sugar content.
- Potassium promotes photosynthetic performance, which leads to increased formation of substances in carbohydrate metabolism (sucrose formation).
- Furthermore, it favors the discharge of assimilates and their incorporation into the beet body.
- Potassium strengthens the plant against diseases, therefore maintaining its efficiency.
- Insufficient potassium levels in the soil jeopardize soil fertility and have a negative impact on yield and sugar content.
Potassium for improved quality in sugar beet
- The most important quality factor of sugar beet is its sugar content.
- Due to its specific physiological effects, potassium has a positive influence on sugar formation, derivation, and storage.
- In trials, an increase in sugar content of 0.5-1.0 % polarization could be measured through optimal potassium fertilization (payout price per tonne of beet increases).
- Potassium and sodium (Na) influence the alkalinity of the raw sugar juice. A minimum alkalinity of the raw juice is necessary for sugar production.
- In some regions, a quality premium is additionally determined by the standard molasses loss (SMV). In terms of fertilization, the standard molasses loss is mainly determined by the α-amino nitrogen content.
- Following the introduction of the quality calculation formula for calculating sugar yield, potassium fertilization has hardly any influence on standard molasses loss, since slightly increasing potassium contents in the beets are overcompensated by decreasing α-amino nitrogen contents. The standard molasses loss therefore remains largely unchanged.
- Optimum potassium supply improves the nitrogen efficiency of the sugar beet.
High sugar yield through balanced nutrition
Magnesium has a particularly positive effect on yield, firstly because it maintains the assimilation performance of the beet leaves for a long time and secondly because it regulates the citric acid cycle during cell respiration and therefore the build-up of important plant constituents (proteins, fats, carbohydrates).
Good sulfur supply favors sugar quality by reducing α-amino nitrogen content. Sulfur deficiency increases the standard molasses loss.
Furthermore, sulfur has the following functions:
Sulfur activates important enzymes in energy and fatty acid metabolism. It is essential for the synthesis of sulfur-containing amino acids, influences overall protein synthesis and thus has a positive effect on yield.
An optimal sulfur supply leads to efficient nitrogen utilization. After all, if there is a lack of sulfur, the nitrogen taken up cannot be converted into proteins and a signal is sent to the roots to take up less nitrogen. Therefore, the plant's need for sulfur must be met for optimal nitrogen utilization.
Sulfur enables sugar beet to maintain its physiological processes optimally even under drought stress and avoid or at least minimize yield losses. Sulfur is a component of the metabolic product glutathione, which, as an antioxidant, renders oxygen radicals formed during drought stress harmless and thus prevents necrosis of the leaves.
Sufficient sodium supply improves water utilization and can partially offset potassium deficiencies during dry periods. Trial results indicate yield increases of 300-600 kg/ha sugar by sodium applications of 20-40 kg/ha.
Boron is important for cell tissue formation and the production of ingredients (e.g. sugar). Boron deficiency leads to heart rot and dry rot and consequently to considerable yield losses.
Manganese has similar metabolic functions to magnesium. It has a positive influence on yield, e.g. through improved assimilation of the beet leaves during vegetation.
Fertilization recommendations for sugar beet
Fertilization aims at maintaining soil fertility to exploit the natural yield potential in the long term. For this purpose, an optimum nutrient content must be achieved in the soil (in Germany, soil content class "C"), i.e. nutrients removed with the harvested crop must be replaced by fertilization. In addition to nutrient removal, there are surcharges for soil-specific losses (for example, through leaching) and for compensating for earlier deficits.
Recommendation for soil fertilization
Nutrients requiring fertilization should be applied in chloride form, as sugar beet is a chloride-loving crop. The best time for potassium fertilization is shortly before sowing.
The following fertilization recommendations are calculated on the nutrient removal of the main crop product on the basis of optimum soil nutrient contents (in Germany soil content class "C"). Surcharges for soil-specific losses due to leaching, fixation, or erosion are not taken into account.
Total removal (incl. harvest residues)
460 K2O kg/ha, 100 kg/ha MgO, 50 kg/ha SO3
Through main crop
160 K2O kg/ha, 50 kg/ha MgO, 25 kg/ha SO3
Recommendation for foliar fertilization
Foliar fertilization effectively supplies the plant with the micronutrients boron, manganese, zinc or copper.
It also supplements soil fertilization with rapidly available macronutrients such as magnesium or sulfur. In phases of strong growth, fertilization through the leaf covers peaks in demand and reliably ensures an optimum supply of nutrients even in dry conditions or when sulfur mineralization is too slow.
This ensures the best yields and qualities. If deficiency symptoms have already occurred, foliar fertilization provides an effective and quickest possible remedy.