Growing Strawberry
Crop Nutrition Advice

Detail of strawberry

View of industrial strawberry crop

Role of nutrients

Nitrogen

Promotes high yields and ensures vegetative growth of the crop

Plays a key role in synthesis of proteins, which are directly involved in growth and yield.

Phosphorus

Promotes development of a good root system. A prerequisite for flowering and hence- number and maintenance of fruits.

Essential for appropriate energy management in the plant. Enhances cell division.

Potassium

Enhances transport of sugars to the fruits. A cofactor of tens of enzymes. Regulates water management, mainly through stomata aperture.

Enhances sugar content of the fruit. Reduces susceptibility to many kinds of abiotic-, and biotic- stresses. Improves deep fruit color, firm flesh, shape, and overall yields.

Calcium 

Promotes cell-wall stability, hence providing the plant 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. Increases Fe utilization.

Carrier of phosphorus in the plant. It is both an enzyme activator and a constituent of many enzymes. Helps obtaining a deep green fruit color.

Sulfur 

A structural component of proteins and peptides. Active in the conversion of inorganic N into protein.

A structural component of various enzymes. A catalyst in chlorophyll production.

Iron

Essential for proteins and chlorophyll synthesis. Important factor in many enzymes, associated with energy transfer and respiratory systems.

Manganese 

Important roles in photosynthesis: Hill reaction (H2O splitting), electron transport, CO2 assimilation. Formation of riboflavin, ascorbic acid, and carotene.

Boron 

Translocation of sugars and carbohydrates. Pollination and seed production. Cell division and cell-wall formation, related to Ca uptake and usage.

Nutrient deficiencies

Nitrogen

Both vegetative growth and fruit production are severely restricted.  Light green to yellow leaves., younger leaves are still quite green from N mobilized from older leaves.
Dark red & purple & yellow to light-green leaves. 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, thus impairing production, Phosphorus deficiency is most common when soil pH is too low (7.0).

Potassium

The old leaves are the most sensitive ones, they exhibit marginal burning and a dark discoloration.  The extension of the petiole into the central leaflet darkens, and the bases of the other leaflets become necrotic too. The serrated tips and margins of the older leaves redden and dry up. It gradually advances inwards between the veins until most of the leaf blade is affected.

Calcium

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 at more severe deficiencies.   Mature and older leaves are generally unaffected. Severe deficiency causes flowers abortion, and death of the growing point, runners and petioles may develop darken lesions.   Fruits are smaller and have a hard texture, root growth is also less.  Leaf tip burn and puckering helps to distinguish this disorder from B deficiency which results in distorted and thicker leaves.

Magnesium

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 are lighter in color and softer in texture. Yields are reduced. Deficiency is revealed mainly in fields that have received high N or K fertilizer 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 sun light. Up until the time the leaves become almost completely white, they will recover upon application of iron. Most often observed when growing in alkaline (pH > 7.0), or calcareous soils, and can be induced also by over-liming, poor drainage, or high concentrations of metallic ions in the soil or nutrient solution.

Phosphorus deficiencies                       

Magnesium deficiencies                              

Iron        

Chlorine sensitivity

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, stunted plant growth, dead roots and plants.  

The maximum permissible chloride level in the soil solution in most cases is 5–7 meq/L, and it somewhat varies by variety. Maximum permissible chloride in irrigation water is 3–5 meq/L.  

Chloride higher than 0.5% in the dry matter of the plant indicates chloride toxicity. 

Fertilization methods

Fertigation drip irrigation in open fields and protected management 

As drip irrigation is so common with this crop, fertilization is generally done by fertigation, using fully-soluble fertilizers, adapting the N-P-K-Ca-Mg ratios according to the crop’s needs at every growth stage. 

In soil the needs of the Strawberry must be covered by  : 

1. Elements naturally present in irrigation water
2. Elements already present un the soil
3. Additional fertilizer inputs to the soil
4. Additional Fertilizer intake by drip

Strawberry needs = Soil input ( stock or mineralization for example) + Water elements + Fertilizers put on the soil + supplements during cultivation ( soluble fertilizers)

Foliar feeding  

This is a common practice in fertilizing strawberries, by tank-mixing the fertilizers with crop-protection products. Foliar feeding boosts plant development, strengthening the plants against abiotic factors (e.g. drought, heat, cold soils), and against biotic factors (e.g. nematodes, pests and diseases), and to correct mineral deficiencies.     

Controlled- release fertilizers 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 usage of N-P-K CRFs has caught quickly, and is now practiced over 55% of the 26,000 country-wide hectares, concentrated mainly in California. 

Normally, one pre-plant application of well-designed CRF granules, like Agroblen, can supply the majority share of the crop’s mineral requirements, achieving high yields of ~ 60 MT/ha of high-quality produce for fresh consumption. Application of additional WSF by fertigation is also common. 

Soilless management in glasshouses 

Strawberries responds very well to intensive nutrition regime under controlled, protected environment, as done with exceptional success in Holland. 

Specific nutrition formulae have been adapted to growth on soilless. 

It is difficult to give fertilization advice above ground, indeed for precise fertilization advice, a water analysis is mandatory as well as the needs of the variety. 

In soilless the needs of the strawberry must be covered by : 

• Elements naturally present in the irrigation water 
• Additional fertilizer intake by drip 

Strawberry Needs = Water elements + Supplements during cultivation (soluble fertilizers)

Water analysis is essential to make fertilization advice