Fruits
Consumers expect fresh, healthy-looking fruit, which should be sufficiently developed and ripened when it is offered for sale. For every fruit grower, this poses the annual challenge of producing quality fruit that can stand up to the critical gaze of buyers. The balanced supply of minerals to the plants can make a major contribution to harvesting "extra class" fruit.
It's all about taste and preservation for fruit
Besides the "external" quality characteristics of fruit, the "internal" factors, such as mineral and vitamin contents, as well as the fruit's content of stress-reducing ingredients, e.g. anthocyanins, are among the value-adding properties. Both of these categories can be significantly improved through optimized plant nutrition.
- Potassium ensures efficient plants, better frost resistance.
- Magnesium guarantees high internal and external quality.
- Sulfur is indispensable for the production of plants' own defense substances.
- Micronutrients control important stages of plant development.
Produce best qualities
In today's fruit growing, the focus is on producing high-quality fruit. The highest quality fruit can only be produced if the fruit trees are supplied with sufficient mineral nutrients. The nutrient removal by the fruit is relatively low compared to agricultural crops, but when measuring fertilization, it must be taken into account that nutrients accumulate predominantly in other plant parts such as wood and the leaves.
Fertilization recommendations in fruit growing are based on the needs of the fruit trees and not on the pure withdrawals by the harvested product.
| Fruit |
K2O (kg ha-1) |
MgO (kg ha-1) |
| Pome fruit (apples, pears etc.) | 90-120 | 20-30 |
| Stone fruit | 100-140 | 30-40 |
| Strawberries | 80-150 | 20-30 |
| Soft fruits | 60-80 | 15-25 |
For pome fruits, the following nutritional requirements can be taken as a general guide (assuming a moderate level of soil fertility)
The most important nutrients for fruits
Potassium – for powerful trees and bushes
- Potassium is involved in many metabolic processes crucial to the yield and quality of fruit.
- Potassium improves water utilization, assimilation performance as well as fruit set and therefore has a positive effect on the yield.
- Quality criteria such as fruit acidity or skin coloration are also positively influenced by potassium.
|
Market value
exterior quality markers |
Health value
interior quality markers |
|---|---|
| Size/weight | Sugar content/acid content |
| Color | Mineral nutrients |
| Shape | Vitamins |
| Taste | Dietary fibre |
| Unblemished by pests and diseases | Bioactive ingredients (e.g. polyphenols) |
Magnesium – guarantees high quality
For a very good quality of the harvested products, it is necessary to ensure the supply of magnesium to the trees and bushes.
- Magnesium not only promotes assimilation, but also plays an important role in assimilate transportation.
- This increases the sugar and acid content of the fruit.
- The formation of aroma substances, as well as the size and coloration of the fruit, is improved.
- Magnesium deficiency is quite common in fruit crops and can be aggravated by high levels of calcium or potassium in the soil.
As observed in a two-year apple trial, the magnesium and chlorophyll content was significantly increased by treatment with epsoMICROTOP. The increase of the Mg content in the fruits led to a better coloration of the fruits.
Sulfur – indispensable for health
- 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.
- Sulfur is irreplaceable in the production of the plant's own defense substances, the so-called phytoalexins.
Great importance is now attached to certain sulfur-containing compounds, such as glutathione, which play a central role in the plant's resistance to diseases and pests.
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 metabolic product glutathione, which, as an antioxidant, renders oxygen radicals produced during drought stress harmless and therefore prevents necrosis of the leaves. - According to recent findings, sulfur-containing compounds are also involved in stress defense against ozone and heat damage.
- Optimized sulfur supply leads to efficient nitrogen utilization. When 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.
Don't forget about micronutrients
Micronutrients such as boron, zinc, and manganese are becoming increasingly important in modern fruit growing. In many soils, they are either deficient or cannot be absorbed sufficiently by the woody plants.
Since micronutrients control important stages of plant development, yield and quality losses can result – even from temporary deficiencies.
- Boron is of great importance for the fertilization of flowers, among other things. Deficiencies result in lower fruit set and malformed fruits.
- Zinc controls numerous enzyme reactions. Insufficient zinc supply results in stunted shoots and leaf discoloration.
- Manganese deficiency increases e.g. apple speckling. Furthermore, the storability of the fruit is greatly reduced.
Micronutrient deficiencies can be remedied effectively and quickly by using foliar fertilizers.
Fertilizer recommendations for fruits
All fruit crops are highly sensitive to chloride and salt. Potassium and magnesium are therefore applied in sulphate form to avoid risks to yield and quality.
Recommendation for soil fertilization
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.
To account for the chloride sensitivity of most fruit crops while meeting their nutrient requirements, low-chloride fertilisers such as PatentKALI, ESTA Kieserit and KALISOP should be used.
In fruit plantations, nutrient requirements can be met with 300–500 kg/ha PatentKALI or 100–300 kg/ha KALISOP. To meet additional magnesium and sulphur requirements, approximately 150 kg/ha ESTA Kieserit can be applied.
In apple production, nutrient requirements can be met with 180 kg/ha PatentKALI or 110 kg/ha KALISOP. For field-grown strawberries, 130 kg/ha PatentKALI or alternatively 80 kg/ha KALISOP is recommended. For soft fruit, 200–600 kg/ha KALISOP can be applied depending on the crop and nutrient requirements.
Product recommendation
Recommendation for foliar fertilization
Foliar fertilization effectively supplies plants with the micronutrients boron, manganese, and zinc.
It also complements soil fertilization with readily available macronutrients such as magnesium and sulfur. During periods of vigorous growth, foliar fertilization meets peak nutrient demand and reliably ensures an optimal nutrient supply, even under dry conditions or when sulfur mineralization is too slow.
This supports optimal yields and quality. If deficiency symptoms have already appeared, foliar fertilization provides rapid and effective relief.
Magnesium and sulfur with epsoTOP®
A total of 10–60 kg/ha is recommended, divided into two to four applications. It can be applied together with crop protection products at a maximum solution concentration of 2 %.
Do not overlook micronutrient requirements
epsoMICROTOP and epsoMULTITOP are recommended to meet micronutrient requirements:
- Strawberries: 10-15 kg/ha divided into 2 to 3 applications at a maximum solution concentration of 2 %
- Tree fruit: 10-20 kg/ha divided into 2 to 4 applications at a maximum solution concentration of 2 %
- Grapes: 10-15 kg/ha divided into 2 to 3 applications together with a crop protection treatment
All epso products are suitable for fertigation.
For acute potassium deficiency or during periods of peak potassium demand, use soluSOP 52 ORGANIC (5-15 kg/ha per application in 2-3 split applications, as a 2-5 % solution).
