crop nutrition advice
crop nutrition advice
Everything you need to know about strawberry fertilisation, best practice, suitable products, field trials and more.
Advice for growing strawberry (Fragaria ananassa)
Strawberries perform best in soils with a pH between 5.5 and 6.5.
In soils with a high pH (above 7.5) phosphorus deficiency may occur, as might micronutrient deficiencies.
In soils with a low pH (below 5.5) phosphorus, molybdenum, and calcium deficiencies may appear.
Best yields are obtained when strawberries are grown on deep, fertile soil, rich in organic matter.
Strawberries are very sensitive to root asphyxia, and so are usually planted on mounds to avoid this phenomenon.
Below 14°C, the development and quality of flowers can be affected.
Irrigation is essential for high-yielding strawberry production. The plant’s root system is shallow, with 80–90% in the top 15 cm of clay, and 50% in the top 15 cm of well-drained sandy loam soils. Therefore, frequent and short irrigation pulses are necessary to maximise production.
Drip irrigation is the most widely used method of feeding. Drip irrigation allows the application of precise amounts of water, and thanks to the use of water-soluble fertilisers, nutrients can be delivered at the same time.
Role of nutrients
Promotes high yields and ensures vegetative growth of the crop
Plays a key role in the synthesis of proteins, which are directly involved in growth and yield.
Promotes the development of a good root system. Phosphorus is a prerequisite for flowering and has a positive effect on the number of fruits.
Phosphorus is essential for appropriate energy management in strawberry plants. It also enhances cell division.
Enhances transport of sugars to the fruits. A cofactor of tens of enzymes. Regulates water management, mainly through stomata aperture.
Enhances the sugar content of the fruit. Reduces susceptibility to many kinds of abiotic- and biotic- stresses. Improves deep fruit colour, firm flesh, shape, and overall yields.
Promotes cell-wall stability providing the plant with a strong structure and resistance to diseases.
Adequate calcium prevents blossom-end rot (BER). It also provides improved shelf life.
Magnesium is the central part of the chlorophyll molecule, playing a key role in photosynthesis. Magnesium acts as a phosphorus carrier in plants and is both an enzyme activator and a constituent of many enzymes.
Sulphur is a structural component of proteins and peptides, and is active in the conversion of inorganic N into protein. Sulphur is also important as a structural component of various enzymes, and is a catalyst in chlorophyll production.
Iron (Fe) is essential for protein and chlorophyll synthesis and is an important factor in many enzymes. Iron is also associated with energy transfer and plant respiratory systems.
Manganese is another nutrient that is important in photosynthesis, essential for the Hill reaction (H2O splitting), electron transport, and CO2 assimilation. It is also important for the formation of riboflavin, ascorbic acid, and carotene.
Boron plays an important role in the translocation of sugars and carbohydrates, and a key role in pollination and fruit set, increasing the viability of pollen grains. Boron is involved in cell division and cell-wall formation and the preservation of cellular membrane functions.
|Nitrogen||Both vegetative growth and fruit production are severely restricted with N deficiency. Plants exhibit light green to yellow leaves, while younger leaves remain quite green thanks to N mobilised from older leaves.
If the n deficiency continues then the yellow to light-green leaves may turn dark red and purple. Yield is reduced and fruit are pale, short and thick.
|Phosphorous||P-deficient plants have weak roots, are stunted, and produce small dark, dull, grey-green leaves.
Leaves become purple-to-brown on their entire blade or on their distal margins (see photos).
Fruit set is reduced, impairing production and yield. Phosphorus deficiency is most common when soil pH is too low (7.0).
|Potassium||Old leaves are the most sensitive to potassium deficiency, exhibiting marginal burning and dark discolouration.
The extension of the petiole into the central leaflet darkens, and the base of the other leaflets become necrotic.
The serrated tips and margins of older leaves redden and dry up, gradually advancing inwards between the veins until most of the leaf blade is affected.
|Calcium||The youngest leaves cup downwards and their edges become scorched. Stunting and necrosis of the youngest leaves and of growing points at top of the plant. Marginal leaf yellowing can also occur with more severe calcium deficiencies. Mature and older leaves are generally unaffected. Severe calcium deficiency causes flower abortion and death of the growing point. Runners and petioles may develop darken lesions. Strawberry fruit are smaller and have a hard texture, root growth is also reduced. Leaf tip burn and puckering help to distinguish this disorder from boron deficiency which results in distorted and thicker leaves.|
|Magnesium||Mg deficiency results in yellowing of older leaves, beginning between the major veins, which retain a narrow green border. In severe situations, a light tan burn develops in the yellow regions. Younger leaves are less affected. Fruits from Mg-deficient plants appear lighter in colour and are softer in texture. Yields are reduced. Deficiency is observed mainly in fields that have received high N or K fertiliser rates.|
|Iron||Yellowing appears on younger leaves first and is distinctly interveinal. All other leaves remain dark green. In severe deficiency, the minor veins also fade and the leaves may eventually burn, especially if exposed to strong sunlight. Leaves will recover with the application of iron, up until the time the leaves become almost completely white. Iron deficiency is most often observed when strawberries are grown in alkaline (pH > 7.0), or calcareous soils, and can also be induced by over-liming, poor drainage, or high concentrations of metallic ions in the soil or nutrient solution.|
Strawberry is considered to be one of the most sensitive crops to salinity in general, and specifically to chloride. Cl-affected leaves show dry and brown leaf margins, brittle leaves, and stunted plant growth, leading to dead roots and eventually causing plants to die.
The maximum chloride level in the soil solution in most cases is 5-7 meq/L, although it somewhat varies by variety. The maximum permissible chloride in irrigation water is 3-5 meq/L.
Chloride toxicity is indicated when analysis reveals chloride levels higher than 0.5% in the dry matter of the plant.
Fertigation in open fields and protected management
As drip irrigation is common with this crop, fertilisation is generally done by fertigation, using fully-soluble fertilisers. The N-P-K-Ca-Mg ratios should be adapted according to the crop’s needs at every growth stage.
The needs of the strawberry crop should be met by:
- Elements naturally present in the irrigation water
- Elements already present in the soil
- Additional fertiliser inputs applied to the soil
- Additional fertiliser intake from fertigation
Foliar feeding is a common practice for fertilising strawberries, involving tank-mixing fertilisers with crop-protection products. Foliar feeding boosts plant development, strengthens the plants against abiotic factors (e.g. drought, heat, or cold soils), and against biotic factors (e.g. nematodes, pests or diseases). Foliar fertilisers are also ideal to correct mineral deficiencies.
Controlled-release fertilisers for strawberry fields
The use of CRFs for strawberry crops is expanding rapidly, as a result of the need to save on workload and increase field productivity. In the US for example, the has been a rapid uptake of NPK CRFs, and it is now practised in over 55% of the 26,000 ha of strawberry crops.
Normally, one pre-plant application of high-quality CRF granules, like Agroblen, can supply the majority of the crop’s mineral requirements, achieving high yields (approximately 60 MT/ha) of high-quality produce for fresh consumption. Application of additional WSF by fertigation is also common.
Soilless management in glasshouses
Strawberries respond very well to an intensive nutrition regime in a controlled, protected environment. This approach has proved to be exceptionally successful in Holland.
Specific nutrition formulae have been adapted for soilless strawberry cultivation.
It is not possible to give general fertilisation advice for soilless cultivation. For accurate fertilisation advice, water analysis and the precise needs of the variety are essential.
For soilless cultivation, the needs of the strawberry must be covered by:
- Elements naturally present in the irrigation water
- Additional fertiliser supplied by fertigation.
Ripening strawberry fruit
Large-scale strawberry crop
Here are some frequently asked questions we received from farmers regarding strawberry cultivation.
Generally, the first application of water-soluble fertilizer takes place 15 days after planting.
No, You can not mix calcium nitrate with a phosphorus product in the same tank. This may precipitate and clog your drippers. If you do not have two injection tanks, use Agrolution Special. Agrolution Special is a unique water-soluble fertiliser product range with NPK, Ca and MgO in a single product.