Methods of Fertilizing Vegetables

2025

4 min read

To obtain rich and healthy vegetable crops, more is needed than just implementing basic growth and care processes. Fertilization is a fundamental aspect of vegetable farming, as it increases crop productivity by providing all the nutrients that plants need while also supporting farmers' efforts to keep diseases and pests at bay.

At the same time, fertilizer application must be done responsibly and based on a thorough analysis of all growing conditions to ensure effective fertilization. In this article, we will present two of the most commonly used fertilization methods in vegetable farming: root fertilization and foliar fertilization.

Root Fertilization of Vegetables

The largest quantities of nutrients are absorbed by plants through their roots, making root fertilization an essential operation for obtaining high-quality, high-yield crops.

A root fertilization plan is always developed based on soil analysis, pH, and salinity, as well as the plant's growth stage.

What fertilizers do we use?

• Organic fertilizers, such as well-decomposed manure or compost, are applied as a base fertilization method by incorporating them into the soil before planting. However, these fertilizers cannot provide all the necessary nutrients throughout the entire vegetation period, especially when high-yield vegetable production is the goal.

• Chemical fertilizers come in the form of granules, powders, and concentrated liquid solutions and can be applied either by spreading them on the soil or through fertigation.

Next, we will discuss fertigation, which is currently the most widely used root fertilization method for vegetables.

What is Fertigation?

Fertigation is the process of applying fertilizers along with irrigation water using a drip irrigation system.

When should fertilizers be applied through fertigation?

Depending on the development stage, plants require different amounts of water and specific nutrients (macro, meso, and microelements), as follows:

• At transplanting, plants require higher levels of phosphorus (P), potassium (K), and calcium (Ca).

• During flowering and fruit setting, they need more nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), and boron (B).

• During vegetative growth and fruit enlargement, they require higher levels of nitrogen (N), potassium (K), and calcium (Ca), while the need for phosphorus (P) decreases.

• At fruit ripening, the demand for potassium (K), phosphorus (P), and calcium (Ca) increases, while nitrogen (N) requirements decrease.

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How is fertigation performed?

• Specially designed products that are 100% water-soluble and free of chlorine and sodium are used to prevent clogging of irrigation system nozzles.

• The required amount of fertilizer is determined based on plant species, growth stage, and area covered (number of plants).

• The fertilizer is dissolved in water in an appropriately sized container to create the nutrient solution.

• It is recommended to apply small amounts of fertilizer more frequently to enhance efficiency and avoid nutrient loss or plant stress caused by high doses. For example, the weekly dose can be divided and applied over several days.

• Before introducing the solution into the irrigation system, plants are watered with a predetermined amount of water. Toward the end of the irrigation process, the nutrient solution is injected, followed by additional irrigation to ensure the complete distribution of the fertilizer.

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How does soil pH affect nutrient absorption?

• A pH of 5.5 enhances the absorption of iron, zinc, copper, manganese, and boron. As the pH approaches 6.5–7, the absorption of these elements becomes more difficult.

• A pH above 6.5 favors the absorption of nitrogen, phosphorus, magnesium, calcium, sulfur, and molybdenum.

• A pH between 6 and 7 promotes phosphorus absorption.

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Advantages of Fertigation

• Uniform application to plant roots, reducing fertilizer usage and overall costs.

• Prevention of surface water pollution caused by fertilizer leaching.

• Reduced disease and pest issues by keeping foliage dry.

• Lower labor requirements.

To achieve high-performance yields and ensure maximum nutrient absorption, root fertilization must be complemented by foliar fertilization.

Foliar Fertilization of Vegetables

Foliar fertilization involves spraying a solution of water and fertilizer directly onto the plant, following the recommended dosage based on plant species and growth stage.

Foliar fertilization is a supplement to root fertilization, playing a key role in enhancing nutrient absorption at the root level.

When should foliar fertilization be applied?

• When nutrient deficiencies appear on leaves, fruits, etc.

• When root systems are affected due to nutrient depletion, disease or pest attacks, oxygen deficiency due to water excess, improper pH levels, or high salt concentrations.

• After transplanting.

• During critical growth phases with high nutrient demands: flowering, fruit setting, fruit growth, and ripening.

• To strengthen plant defenses against diseases and pests.

  
  

How is foliar fertilization performed?

• Foliar fertilizers are applied using sprayers, manual or electric pumps, or atomizers.

• The spraying equipment should be adjusted to create a fine mist, avoiding large droplets that could run off the leaves.

• The recommended dosage and water quantity must be carefully followed, depending on the plant’s growth phase.

• To prevent sedimentation of the fertilizer at the bottom of the container, it should be fully dissolved and continuously stirred during application.

• Nutrients penetrate the plant through both the upper and lower surfaces of the leaves, so it is advisable to spray both sides.

• Using a surfactant (adjuvant) can improve solution adherence and absorption, particularly for crops with thick, waxy leaves such as cabbage and onions.

  
  

Important Considerations for Foliar Fertilization

• Always follow recommended dosages to avoid harming plants.

• Check for compatibility with other fertilizers or pesticides when applying them together.

• Avoid application during high temperatures and strong sunlight to prevent leaf burns.

• Do not apply in windy conditions to ensure proper solution coverage on plants.

  
  

What products should be used?

A wide variety of specially designed foliar fertilizers are available on the market, including chemical or organic formulations in liquid, gel, powder, or granule form, all of which are 100% water-soluble.

Advantages of Foliar Fertilization

• Immediate correction of nutrient deficiencies as soon as symptoms appear.

• Faster nutrient absorption compared to root application.

• Additional nutrient supply during high-demand growth phases.

• Stimulation of plant metabolism.

• Can be applied alongside plant protection treatments.

  
  

Disadvantages

• In cases of severe deficiencies, foliar fertilization alone is not sufficient, and root fertilization is also needed.

• Improper application can cause leaf burns.

• A smaller quantity of fertilizer is applied per session compared to root fertilization.

• Multiple applications may be required due to incompatibility with other foliar fertilizers.

• Application is dependent on environmental factors such as wind and precipitation.