Vegetables a complex variety – taste, appearance, quality, and yield
In the cultivation of vegetables, quality is the top priority. For this purpose, particular attention must be paid to providing the crops with an adequate supply of minerals, as they are decisive for the formation of the value-giving constituents. This applies to outdoor crops as well as to protected cultivation.
- Quality vegetables for human nutrition through balanced fertilization of the plants.
- Potassium is important for yield security.
- Optimize market value with magnesium fertilization.
- Taste and aroma are improved by sulfur supply.
Quality for human nutrition
Vegetables play a special role in human nutrition. Vegetables are simply healthy due to the richness of value-giving ingredients and the very low fat content. Furthermore, vegetables significantly contribute to the supply of minerals to the human body. Fertilization must therefore be given special importance.
Unlike agricultural crops, the harvest time of vegetables is often in the middle of vegetative development. Therefore, a sufficient supply of nutrients must be provided in time.
Vegetable production is one of the most demanding areas of crop production. The high nutrient requirements of the crops are particularly pronounced in leafy and tuberous vegetables.
Quality vegetables must meet many requirements
Interior quality, health quality
Premium vegetables need to meet a range of requirements
The most important nutrients for vegetables
Potassium – for yield security
Optimum potassium supply is a basic prerequisite for the cultivation of high yields and top qualities. Most vegetables are characterized by a high potassium requirement. This is about one third higher than the nitrogen requirement. The amount of potassium fertilization depends on the nutrient removal, whereby five vegetable groups can be differentiated.
|Broccoli, french beans, peas, lamb’s lettuce, radicchio, red radish, Brussels sprouts, runner beans, asparagus
|Cauliflower, kale, lettuce, parsley, leeks, spinach, sweetcorn, onions
|Chinese cabbage, oak-leaf lettuce, kohlrabi, savoy cabbage
|Chicory, iceberg lettuce, endive, white radish, red cabbage, tomato, white cabbage
|Fennel, carrot, red beet, celeriac, zucchini
Grouping of vegetable species according to the level of potassium removal by market yield.
Which potassium fertilizer is right for which crops?
Most field vegetables are very sensitive to chloride, at least during their juvenile stage (as seedlings and as plantlets). This is why fertilisation before sowing and before planting, as well as top-dressing should always include sulphate forms of potassium and of magnesium.
The beneficial effects of sulphate based potassium fertilizers can be shown in numerous studies, among others by comparison of the germination rates.
Magnesium and sulfur – for ensuring quality
Sulfur – for premium quality
For the purpose of producing the best quality, all field vegetables require a relatively high sulfur supply in addition to potassium and magnesium.
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.
In vegetables, S-fertilization positively influences the formation of leek and mustard oils, which are responsible for taste and aroma, as well as the typical taste and smell of various types of cabbage and asparagus.
Optimal 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 in order to make optimal use of nitrogen. Sulfur deficiencies can also lead to an increase in nitrate levels in crop products.
Sulfur enables the plant to maintain its physiological processes optimally even under drought stress and prevent 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 therefore prevents necrosis of the leaves.
Magnesium – increases market value
Magnesium, the nutrient for leaf green, is responsible for the coloration of the harvested produce. A lack of green coloration leads to a significantly reduced market value for numerous types of vegetables. It also leads to metabolic disorders in the plant and often to nitrate accumulation. The magnesium requirement is comparable to that of phosphate. Depending on the yield level and type of crop, plants take up 30-70kg MgOha-1.
Overview of chloride-sensitive and chloride-tolerant vegetable varieties
|Particularly sensitive to chloride during the entire vegetation period
Fertilizer recommendation for vegetables
Since most vegetables are sensitive to chloride, particular importance should be attached to the use of mainly chloride-free fertilizers. The best time for sulfate potassium fertilization is shortly before planting.
Recommendation for soil fertilization
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.
Recommendation for foliar fertilization
Foliar fertilization effectively supplies the plant with the micronutrients boron, manganese, and zinc.
It additionally supplements soil fertilization with rapidly available macronutrients such as magnesium and 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.
epsoTOP may be used as a supplementary measure for soil conditioning; otherwise epsoMICROTOP as a preventive treatment of boron and manganese deficiencies. Use once or twice, as 2-3%-solutions (20-23kg/ha).