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How to Use NPK Foliar Fertilizers

NPK foliar fertilizers boost leafy growth and overall plant health. Learn how and when to use them for lush foliage in your garden.

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Whether you are a seasoned gardener, an agricultural enthusiast, or a newbie to plant care, you are always looking to nurture your plants. This is especially true for growing healthy foliage to add beauty to the surroundings and make your plants more productive. NPK foliar fertilizer may be the answer to boosting plant growth and overall plant health. These fertilizers are rich in nutrients and are capable of optimizing the nutrient uptake through the leaves. In this article, we will discuss what NPK foliar fertilizers, their benefits, how and when to use them, and where to apply them for optimum results. 

What are NPK foliar fertilizers?

NPK foliar fertilizers are liquid fertilizers formulated with NPK and compatible adjuvants. Adjuvants are sticking agents that help avert fertilizer runoff. Generally, these fertilizers are applied directly to the plant foliage to support the phenological stages of the plant. One can prepare them as per the requirements of the plants, whether they need micronutrients to overcome deficiencies, hasten growth, or strengthen weak crops.

While NPK soil fertilizers require moisture to dissolve and provide their benefits, NPK liquid fertilizers are readily available. These can be used to produce all agricultural, fodder crops, horticultural, lawns, trees, and turf.

NPK foliar fertilizers are of two types. Low-volume NPK foliar fertilizers may be sprayed on field crops, whereas high-volume sprays are considered ideal for horticultural crops. 

The best ratio of NPK foliar fertilizer for lush foliage growth is 15-30-15 or 20-20-20.

NPK foliar fertilizers soil health enhancement

What conditions require foliar fertilization?

Foliar fertilization is helpful in promoting healthy plant growth in conditions such as:

  • Dry soil
  • High/low pH
  • Excessive moisture
  • Cold temperatures
  • High alkalinity 

Role of the N, P, and K for Your Plant?

NPK foliar fertilizers consist of three main ingredients: nitrogen (N), phosphorus (P), and potassium (K). All three have different roles to play.

Nitrogen (N): The most commonly used nitrogen fertilizer in NPK foliar fertilizer is urea. While ionic compounds such as ammonium nitrate can burn the leaves, the probability with non-ionic compounds such as urea is much less. Urea is available in three forms: prilled grade, granules, and ready solution. Prills dissolve faster than granules as they are smaller in size.   

Potassium (K): Known for enhancing root development, phosphorus is often applied as a soil fertilizer. When used as foliar fertilizer, the two most popular forms are monoammonium phosphate (MAP) and monopotassium phosphate (MKP). MAP and MKP contain nitrogen and potassium, respectively, reducing the need for nitrogen and potassium fertilizer in other forms.

Phosphorus: After nitrogen, phosphorus is the second most essential nutrient for plant growth. When used as a soil fertilizer, potassium chloride is more popular. However, both potassium nitrate potassium sulfate (Sulfate of Potash) and potassium nitrate (Nitrate of Potash) can be used in foliar sprays. 

Other nutrients present in NPK foliar fertilizers as per the requirement include calcium, magnesium, sulfur, molybdenum, and boron. 

What are the benefits of NPK foliar fertilizers?

Plants absorb foliar fertilizers faster than the soil fertilizers. Here’s why:

Better Fertilization

Blockages, soil leaching, and other losses may not allow the plant to ingest all the nutrients added to the soil. However, with foliar fertilization, the nutrients are delivered directly to the plant.

pros of NPK foliar fertilizers

Overcome weather resistance

Foliar fertilizers are recommended to stimulate plant growth during cold seasons or early spring when soil fertilizers are ineffective due to low soil temperatures.

Address nutrient deficiency

Foliar fertilization with essential micronutrients like calcium, copper, zinc, manganese, and iron can help plants grow well when their roots cannot provide enough nourishment.

No new leaves

A plant with no new leaves indicates phosphorus deficiency. NPK foliar fertilizer is the perfect solution for such plants. 

Sustainable practice

Fertilizer runoff is a common problem, polluting the agricultural soil with chemicals. Replacing it completely or partially with foliar fertilizers can help in promoting environment-friendly fertilization methods. Apply these in smaller amounts.  

How to use NPK as foliar fertilizer?

Before using an NPK foliage fertilizer, read the manufacturer’s instructions carefully. Then:

Prepare the solution: Dissolve the granules or pellets in water. The ratio of NPK to water is 1% and 2%, respectively.

Test the solution: Before applying the mixture, test it on a small area to prevent leaf burn. 

Apply the mixture: Take the blend in a sprayer (a knapsack sprayer or a motorized sprayer). Then, spray it on the plants in the late evening or early morning when the sun’s rays are less harsh. 

Repeat: Spray again on the leaves after 1-2 weeks or as per the requirement to boost foliage growth. 

Where to apply NPK foliar fertilizer in Your Plant?

Whether you are using the liquid formulation or the powdered form, NPK fertilizer is found to stimulate healthy plant growth. The right place to apply NPK foliar fertilizer is on the upper and lower surfaces of the leaf, including the stomata.

It must be noted that the pH of the foliar fertilizer is between 6.2 and 7.0. Alkaline blends suit early plant growth, whereas acidic formulations work well for the “production” stage.

Tip: To ensure that the NPK liquid fertilizer stays for a long on the leaf, add a small amount of insecticidal soap to it. 

How do you know it’s time to apply foliar fertilizer?

The right time to apply foliar fertilizer is when the plant starts showing the following signs and symptoms:

the time that can apply foliar fertilizer

  • Change in leaf color
  • Stunted growth
  • Poor root growth
  • Slow or inhibited plant growth

How do you buy NPK foliar fertilizer for your plants?

The choice of foliar fertilizer depends on the composition of the soil and the plant’s condition. Generally, it is advised to buy a fertilizer with a small amount of nitrogen and phosphorus. These may not be needed but ensure satisfactory absorption of other micronutrients added via the NPK foliar fertilizer. 

FAQs Related to NPK Foliar Fertilizers

What is the best way to apply foliar fertilizer?

The best way to apply foliar fertilizer is as a fine spray directly onto the leaves of the plant. This allows for efficient absorption of nutrients through the leaf surface.

Yes, NPK fertilizer can be applied as a foliar spray. In fact, foliar spraying is a common method for delivering NPK nutrients to plants.

The best time to apply foliar fertilizer is during the early morning or late afternoon when the weather is cooler, and the sun’s intensity is lower. This helps prevent leaf burn and allows for better absorption of nutrients.

Yes, you can spray NPK fertilizer on the leaves of the plant. Foliar spraying is an effective method for delivering nutrients directly to the plant’s foliage.

For leaf growth, nitrogen (N) is the most important nutrient, so an NPK fertilizer with a higher nitrogen content is needed. A balanced fertilizer with a higher percentage of nitrogen (such as 20-10-10) can promote lush leafy growth.

Conclusion

It’s true that NPK fertilizers boost plant growth and overcome other nutritional deficiencies, but they do not improve the plant’s performance in the long run. Your plant may still require compost and other soil fertilizers from time to time. Therefore, the importance and usefulness of these cannot be undermined, especially in the conditions described in this article. 

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