Sunflower
Its oil is favored in the kitchen, the grist is popular in animal feed, and it's beautiful at the time of flowering. Across the EU, sunflowers bloom annually on more than 4 million hectares. This makes the plant the second most important oil crop in Europe in terms of cultivation. If you want to achieve high yields, you must carefully adapt your choice of variety, sowing rate, and fertilization to the respective location.Likewise, the sowing rate should be adapted to the particular location. The better the soil, the higher the seeding density can be selected. In dry conditions, lower seeding rates are recommended. It is very stable in yield in dry and hot years or on dry land.
Sunflower – a demanding oil crop
For germination, sunflower requires soils that warm up easily and about 150 frost-free days until harvest which is usually at the end of September. The total temperature demand during the growing season is high. Sufficient water supply at the time of flowering and persistently dry weather at the onset of maturity from August are very important.
- This demanding oil crop provides valuable yields when fertilization is specifically adapted.
- Sunflower has a high potassium requirement.
- Sulfur and magnesium are important nutrients to secure high oil content.
- The demand for the micronutrients boron and manganese is high.
Sunflower – best quality with sun, nutrients, and water
Due to their high temperature requirements, the cultivation of sunflowers for oil production in the food sector is limited to climatically favorable regions. Sunflowers can be successfully grown where grain corn varieties of the medium maturity group also ripen reliably. On the other hand, sunflower has higher water requirements than corn during flowering, so successful production requires adequate rainfall or irrigation and soils with high water holding capacity.
Sunflower has an extensive root network and fibrous root system, which means that the plant is well protected against drought during the rest of the growing season. Sunflower absorbs large amounts of nutrients due to its large leaf and stem mass. Adequate nutrient supply through fertilization during the growing season is therefore important for good management of the crop.
The variety suitable for the particular location must be selected in order to achieve high yields.
Particular attention should be paid to the following criteria:
- Grain yield
- Oil content
- Early maturity/required temperature sum
- Yield stability
- Disease tolerance
- Herbicide resistance
- Marketing direction (LO varieties with >70% linoleic acid content, HO (high oleic) varieties with >80% oleic acid content, striped birdseed varieties).
More facts about sunflower:
- As an emerging oil crop, sunflower provides valuable yields when fertilized selectively.
- Sunflowers have high potassium requirements.
- Sulfur and magnesium are important to ensure oil content.
- The demand for the micronutrients boron and manganese is high.
- In wet years, sunflowers are vulnerable to diseases.
- Sunflowers achieve good nutrient mobilization due to intensive root growth.
- The nitrogen requirement of sunflowers is relatively low.
The most important nutrients for sunflowers
Potassium – highest requirement for yield and quality
- Sunflower has a very high potassium requirement.
- During vegetation, about 300-400kg/ha K2O are taken up by the crop.
- Most of the potassium supply is needed to build up the large leaf and stem mass of the plants, while only about 80kg/ha K2O is contained in the seeds.
- Optimized potassium supply improves water utilization and increases resistance to drought.
- Potassium improves resistance to diseases and promotes sturdiness. This creates the basis for high yields.
- Potassium activates enzymes responsible for oil formation and therefore increases the oil content in the achenes.
- Due to the fact that sunflower is often cultivated in drier climates, where accumulation of chloride may occur, the use of potassium sulfate (SOP) is recommended.
Sulfur and magnesium – for securing the oil content
Sulfur – for protein formation and nitrogen efficiency
- With 40-50kg/ha S, sunflower has a similarly high sulfur requirement as canola.
- Optimized sulfur supply leads to more efficient nitrogen utilization. This has a positive effect on yield.
- Sulfur plays special roles in the fat metabolism of sunflower and is therefore indispensable for high oil contents.
An optimized sulfur supply leads to efficient nitrogen utilization. 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 optimum nitrogen utilization.
Sulfur enables the plant to maintain its physiological processes optimally even under drought stress and to avoid or at least minimize yield losses. Sulfur is a component of the important antioxidant glutathione which, renders oxygen radicals, formed during drought stress, harmless and thus prevents necrosis of leaves and other plant tissues.
Magnesium
- A well-developed crop takes up about 50-70kg/ha MgO within a short period of time.
- An adequate magnesium supply guarantees a long-lasting assimilation of the sunflower leaves and therefore positively affects yield formation.
- Magnesium has a regulating effect on the citric acid cycle in cell respiration and in this way increases oil formation.
Boron and manganese – two important trace elements
Boron
- Sunflower has relatively high boron requirements.
- A crop that is well supplied with boron can optimally develop its tuft and fibrous root system, contributing to proper nutrient uptake from the soil.
- Boron also influences the growth of above-ground components. Deficiency, for example, leads to deformation of the flower heads and consequently to yield losses.
Manganese
- Manganese is involved in the control of photosynthesis. This improves the assimilation performance of the sunflower and assimilation performance of sunflowers and has a lasting positive effect on yield.
- Through its regulating effect in fatty acid metabolism, manganese ensures a high oil content.
Sunflower fertilizer recommendations
The nutrients to be applied should be supplied in sulphate form, as sunflowers are chloride-sensitive crops. The best time for potassium fertilisation is shortly before sowing.
The following fertilisation recommendations are calculated based on the nutrient removal by the main harvested product and assume optimum soil nutrient levels (soil nutrient status class “C” in Germany). Allowances for site-specific losses through leaching, fixation or erosion are not included.
Recommendation for soil fertilization
- Depending on the yield level, 300 to 600 kg/ha Korn-KALI when fertilising in autumn to meet potassium requirements while also ensuring the supply of magnesium and sulphur. Alternatively, 250-500 kg/ha Roll-KALI.
- 450-700 kg/ha PatentKALI for spring fertilisation, e.g. on light soils, to ensure the supply of potassium as well as magnesium and sulphur without increasing the chloride content of the soil.
- 150-250 kg/ha ESTA Kieserit GRAN. in cases of acute magnesium and sulphur deficiency.
Product recommendation
Recommendation for foliar fertilization
Foliar fertilisation can be used to specifically ensure the supply of micronutrients, particularly boron. At the same time, it complements soil fertilisation by rapidly supplying magnesium and sulphur.
During periods of vigorous growth, foliar fertilisation meets peak nutrient demand and reliably ensures optimum nutrient supply even under dry conditions or when sulphur mineralisation is too slow.
This ensures optimum yields and quality. If deficiency symptoms have already occurred, foliar fertilisation provides effective and rapid relief.
Product recommondation
For magnesium and sulphur supply, two to three applications of 10–15 kg/ha epsoTOP each are recommended.
To meet peak demand and in cases of boron deficiency, epsoBORTOP can be applied twice at 10–15 kg/ha each.
Applications are recommended from the 8-leaf stage until the flower buds become visible.
