Deficiency and Excess of Micronutrients in Plants: How to Identify and Address Them?

Micronutrients, though required in minimal doses, are critical for the proper development of plants. These invisible helpers are involved in essential processes, from cell formation to photosynthesis and nutrient absorption. A lack of micronutrients slows plant growth, leaving them vulnerable to external factors. However, any imbalance—be it a deficiency or an excess—can lead to serious consequences. In this article, Bonaplant will explain how to identify when plants need additional nourishment, when intervention is required to prevent the negative effects of excess micronutrients, and how to create optimal conditions for their growth and development.

Micronutrients are a group of chemical elements, each performing unique functions necessary for the healthy growth of plants:

• Boron (B): Participates in cell division and tissue formation. It is particularly important for flowering, fruit setting, and root system growth.
• Zinc (Zn): Activates enzymes and is involved in the synthesis of growth hormones. It is essential for green mass formation and the proper development of shoots.
• Copper (Cu): Plays a vital role in photosynthesis, plant respiration, and the formation of cell walls. It also enhances resistance to pathogens.
• Iron (Fe): Necessary for the synthesis of chlorophyll and enzymes involved in respiration.
• Manganese (Mn): Involved in photosynthesis and nitrogen metabolism.
• Molybdenum (Mo): Helps plants assimilate nitrates and contributes to protein synthesis.
• Chlorine (Cl): Regulates osmotic pressure in cells and participates in photosynthesis.
• Nickel (Ni): Required for nitrogen processing and the activation of the enzyme urease.

All these micronutrients are essential for plants' normal functioning, making their balance in soil and fertilizers crucial.

Micronutrient deficiency in the soil leads to significant developmental issues in plants. The symptoms of deficiency vary, and each deviation is linked to the lack of a specific micronutrient. Identifying these symptoms promptly is key to addressing the problem effectively.

• Boron deficiency often manifests as hollow cavities inside fruits and rotting of their cores. Dry spots appear on the leaves, root growth slows down, and flowering becomes less intense. Plants lacking boron pollinate poorly, resulting in fewer fruit sets.
• Zinc deficiency leads to stunted growth and smaller, rigid, pale leaves. Spots may appear on young shoots, and the internodes become noticeably shorter. This is particularly dangerous for fruit trees, as it disrupts fruit formation.
• Copper deficiency causes leaves to wilt, lose turgor, and turn pale. Young plants exhibit slowed growth, and their root systems develop weakly. Plants often become more susceptible to fungal diseases.
• Iron deficiency is commonly signaled by chlorosis. Young leaves turn yellow while retaining green veins, whereas older leaves remain unaffected. This condition is especially prevalent in plants grown on alkaline soils.
• Manganese deficiency results in leaves developing light spots with green veins. Photosynthesis becomes less efficient, weakening the plant overall.
• Molybdenum deficiency typically impacts nitrogen metabolism. Leaves deform and curl, young shoots lose vigor, and the plant's overall growth slows significantly. This is especially noticeable in legumes.
• Chlorine deficiency causes leaves to wilt and dry at the edges, reducing the plant's ability to retain moisture. General plant weakening and decreased drought resistance are often observed.
• Nickel deficiency leads to the accumulation of toxic forms of nitrogen in the plant, adversely affecting growth. Seeds develop poorly or lose their ability to germinate altogether.

Timely detection of micronutrient deficiencies in plants helps minimize their negative impact.

As previously mentioned, plants require only small amounts of micronutrients. Their excess can be just as harmful as a deficiency. Micronutrient levels above the norm result in soil toxicity and disrupt plants' physiological processes.

Common symptoms of excessive micronutrients include:

• Stunted plant growth;
• Root damage (burns, necrosis);
• Changes in leaf color and texture (spots, curling);
• Reduced yield and fruit quality.

These symptoms can vary depending on the specific micronutrient involved. Let’s examine how an excess of each impacts plant health:

• Excess boron in the soil causes leaf edge burns, turning them brown. Leaves may drop, and the root system weakens. Boron toxicity is particularly dangerous for sensitive crops, such as grapes and citrus.
• Excess zinc suppresses plant growth, causing chlorosis and spots on leaves. Young shoots may become deformed, and root development slows. Zinc toxicity is often found in soils enriched with industrial waste.
• Excess copper damages root systems and causes necrotic spots on leaves. Plants become brittle and struggle to withstand drought. Copper toxicity also reduces the availability of other micronutrients, such as iron and zinc.
• Excess iron results in leaf darkening, rusty spots, and stunted growth. Iron toxicity is common in acidic soils where the element becomes more available to plants.
• Excess manganese causes dark spots on leaves, sometimes with yellow edges. Shoots become brittle, and roots lose their ability to absorb water and nutrients effectively.
• Excess molybdenum disrupts nitrogen metabolism and leads to toxicity, seen in leaf curling and stunted growth.
• Excess chlorine dries out leaves, causing yellowing and defoliation. Plants sensitive to salts, such as grapes, strawberries, and citrus, are particularly affected.
• Excess nickel slows growth, yellows leaves, and accumulates toxic compounds in plant tissues, impacting the quality of fruits and seeds.

Excess micronutrients not only hinder plant growth but also reduce soil fertility over time. Common causes include:

• Overuse of fertilizers containing micronutrients;
• Soil contamination from industrial waste or chemicals;
• Improper combination of fertilizers.

Balanced micronutrient levels in the soil are essential for healthy plant development and high yields. To avoid both deficiency and excess, a comprehensive approach is critical.


Soil and Plant Analysis

The first step in maintaining the balance of micronutrients is regular soil analysis. This process helps determine the nutrient content and identify which elements are deficient or, conversely, in excess. Soil analysis allows for precise calculation of fertilizer dosages, helping to avoid over-application of micronutrients that can lead to toxicity.

Micronutrient deficiencies in plants can also be identified through leaf analysis. This method helps promptly detect deficiency symptoms of essential nutrients and adjust plant nutrition through foliar feeding.


Choosing the Right Fertilizers

To address micronutrient deficiencies, the following fertilizers can be used:

• Mineral Fertilizers: Boric acid, zinc sulfate, iron sulfate, copper sulfate, and similar options quickly replenish micronutrient shortages.
• Organic Fertilizers: Sapropel, biohumus, and compost not only compensate for micronutrient deficiencies but also improve soil structure and aid its restoration.

To prevent micronutrient excess, it is advisable to use complex fertilizers with a carefully balanced composition that considers the specific needs of crops and soil types.


Foliar Feeding

Foliar feeding, or foliar application, is an effective method for quickly addressing micronutrient deficiencies. This involves spraying plants with fertilizer solutions containing the missing elements. Foliar feeding delivers micronutrients directly to plant tissues, bypassing soil barriers. This method is particularly beneficial for crops experiencing acute deficiencies or when the root system is damaged.


Dosage Control and Regular Application

Controlling dosages and applying fertilizers regularly are key to preventing micronutrient excess and avoiding their accumulation in the soil. Regular use of organic fertilizers helps maintain the micronutrient balance in the soil. Organic matter neutralizes excess levels of certain elements and improves the absorption of others, creating more balanced plant nutrition.


Considering Soil and Crop Characteristics

Each soil type has unique characteristics that influence micronutrient availability. For instance:

• Acidic soils can lead to an excess of manganese or iron.
• Alkaline soils can hinder the absorption of zinc and boron.

Considering these factors, it is essential to select fertilizers and dosages tailored to the soil type and the specific needs of the cultivated crops.

Micronutrients are an essential component of plant nutrition, significantly impacting their growth, health, and yield. However, both deficiencies and excesses can result in negative consequences. To provide plants with balanced nutrition, it is crucial to conduct timely soil diagnostics, select appropriate fertilizers, and strictly adhere to application rates.

At Bonaplant, we are dedicated to helping you achieve healthy, productive plants through optimal nutrition and expert advice. By maintaining the right balance of micronutrients, you can ensure robust plant growth, increased resilience, and improved yields.

Bonaplant operates its own fertilizer production facilities and offers a wide range of micronutrient-enriched products tailored to various soil types and crops. Using high-quality fertilizers creates optimal conditions for plant growth, enhancing their resilience to environmental stress. The balanced application of Bonaplant’s micronutrient fertilizers is the key to successful and eco-friendly farming practices.