SQM Treatments for Blueberries: Boosting Productivity and Quality

In berry crops, the most extracted nutrients are Potassium, Nitrogen, and Calcium, which explains their direct impact on fruit yield and quality.

Potassium is essential for size and firmness, Nitrogen promotes vegetative growth, and Calcium ensures resistance and longer post-harvest life.

Fresh and frozen markets demand strict quality parameters:

• Appearance: uniform color, adequate size, good shape, and absence of defects.
• Firmness: key for transport and shelf life.
• Flavor: soluble solids, balanced acidity, and aromatic compounds.
• Nutritional value: aporte de vitaminas A y C, entre otros antioxidantes.

To meet these standards, balanced nutrition in berries is recommended, considering:

• Adjusting the nutritional plan to the expected yield with a balance of macro and micronutrients.
• Maintaining adequate ratios between cations (Ca/K, Ca/Mg, and (Mg+K)/Ca).
  Using soluble, chlorine-free sources of Potassium.
• Rely on diagnostic tools such as soil and leaf analysis, suction probes, or chlorophyll meters.
• Fractioning nutrient application according to the plant’s stage of extraction.
• Implementing precision fertigation principles, ensuring efficiency and sustainability.

An efficient fertilization plan for blueberries and berries must include both macronutrients and micronutrients, applied in the correct dosage and at the right time.

SQM, through its Specialty Plant Nutrition (SPN) product line, offers high-purity soluble alternatives for fertigation, soil or foliar applications, ensuring greater efficiency and profitability in cultivation.

Fertigation is based on agronomic principles such as Liebig’s Law of the Minimum, which states that the lack of a single nutrient limits total yield.

Therefore, when choosing soluble fertilizers, it is key to consider their solubility (ability to dissolve in water), their electrical conductivity (EC), which reflects the effect on soil salinity, and the pH in solution, since depending on the type of soil and crop, acidic, neutral or alkaline reaction products are required.

Based on these parameters, SQM designs specific nutritional plans for blueberries in full production, optimizing the use of water and nutrients through precision fertigation.

This allows producers to obtain larger, firmer fruits with a longer post-harvest life, meeting the demanding standards of the international market.

Nutritional Plan for Blueberries with Fertigation in Full Production:

In the cultivation of blueberries and other berries, water management is crucial for growth and productivity.

Factors such as application time, infiltration rate, and irrigation frequency must be adjusted to the soil type, the phenological stage of the crop, and the evapotranspiration of the plant. Both excess and lack of water have negative effects on fruit development and quality.

The greatest water absorption occurs near the stem, in the first 20 to 30 cm of the soil profile, so maintaining adequate moisture in that area is essential.

Water requirements vary according to climate and agroecological region, which means that irrigation programs must be adjusted to local conditions.

Blueberries lack root hairs, which limits their natural absorption capacity and makes them highly sensitive to drought.

Therefore, a drip irrigation system is recommended to maintain a constant level of moisture, especially during the critical stages of growth and fruit ripening, when water demand is at its highest.

Salinity refers to the concentration of salts present in the soil or in a nutrient solution. It is measured by electrical conductivity (EC), expressed in mmhos/cm: the higher the value, the greater the concentration of salts in the soil water.

Berries, including blueberries, are crops that are highly sensitive to high levels of electrical conductivity. A solution that is too concentrated in salts interferes with root absorption, directly affecting growth and yield.

When the concentration of salts in the soil water is higher than inside the plant cell, water absorption is prevented. As a result, the plant cannot hydrate properly and ends up showing symptoms of water stress and wilting, even when there is sufficient water available in the soil.

Blueberry tolerance limits to salinity, Source: (Hirzel and Rodriguez 2003)

To achieve efficient nutrition in blueberries through fertigation, it is essential to consider the phenology of the crop.
Organizing each stage of development over time, according to the area, allows us to define which nutrients to apply and in what quantity, ensuring a timely supply along with water.

• Dormancy: The plant enters a metabolic recess, without consuming water or nutrients. It only uses reserves stored in chemical compounds.
• Activation: After accumulating hours of cold, starches are transformed into sugars. Nutrients are mobilized to buds and shoots thanks to internal reserves.
• Sprouting: The first leaves appear and the plant begins to absorb water and nutrients from the soil.
• Development: High cellular activity and formation of new organs. Calcium is key, as it integrates into the plant’s structures with high mobility in this phase.
• Growth: Increase in organ size, greater demand for water and nutrients, especially Nitrogen, with strong dependence on external supply.
• Flowering: Maximum root absorption of water and nutrients. Potassium is essential because it transports carbohydrates to the reproductive organs.
• Fruit-Setting: Pollination marks the beginning of fruit filling.
• Fruit filling: Stage of greatest demand for nutrients and water, especially Potassium, which is vital for fruit size and quality.
• Rippening: The fruit reaches its maximum size and begins to change color. It is the main organ demanding photosynthates.
• Harvest: Removal of fruit according to commercial parameters of color, firmness, and flavor.
• Post-harvest: Root activity is reactivated and reserves are accumulated in roots and wood. This is a key time to apply nutrients and prepare the plant for the next season.