The Importance of Copper in Plant Nutrition

Copper (Cu) is an essential micronutrient in crop production, playing several critical roles in the plant:

1. Enzymatic functions: Copper is vital for various enzymatic activities, including those involved in photosynthesis and respiration. Copper acts as a cofactor for enzymes involved in the synthesis of proteins and carbohydrates,
2. Chlorophyll production: Copper is a cofactor for several enzymes involved in the synthesis of chlorophyll. It is also essential for the proper functioning of the electron transport chain in chloroplasts. Copper-containing enzymes, such as superoxide dismutase, protect chloroplasts from oxidative damage.
3. Lignin formation: Copper aids in the formation of lignin in cell walls, which is crucial for plant structural integrity and resistance to stress.
4. Pollen viability: Copper is important for pollen formation and viability. Adequate copper levels ensure proper pollen tube growth, which is necessary for successful fertilization and seed set

Copper is present in the soil mainly as Cu²⁺ ions. These ions are absorbed by plant roots. Copper is considered a relatively immobile nutrient in plants. This means that once it is incorporated into plant tissues, it does not easily move from older to younger tissues. As a result, deficiency symptoms typically appear first in the youngest leaves and growing points.

When copper levels are insufficient, plants can exhibit a range of symptoms, experience reduced growth, and become more susceptible to diseases.

What are the symptoms of copper deficiency?

1. Chlorosis: One of the most common symptoms is the development of chlorosis, which appears as yellowing of young leaves. The chlorosis typically starts at the tips and margins of the leaves.
2. Necrosis: As the deficiency progresses, necrotic (dead) areas may develop on the edges of leaves or between the leaf veins. These areas may turn brown and crispy.
3. Stunted growth: Copper deficiency can lead to reduced growth in plants, including shorter stems, smaller leaves, and a general lack of vigor.
4. Distorted growth: In some cases, distorted or twisted growth may occur, affecting the overall appearance of the plant. Leaves may appear twisted, curled, or misshapen.
5. Poor fruit or seed development: Copper-deficient plants may produce fewer or poorly developed fruits or seeds.

Copper deficiency symptoms in citrus crop. (Photo courtesy of ICL Brazil)

Copper deficiency symptoms in citrus crop. (Photo courtesy of ICL Brazil)

What are the impacts of copper deficiency?

1. Reduced photosynthesis: Copper is essential for the functioning of enzymes involved in photosynthesis. Deficient plants may have decreased photosynthetic capacity, leading to reduced energy production and growth.
2. Susceptibility to diseases: Copper is involved in the synthesis of lignin, which helps strengthen cell walls and provides resistance against pathogens. Copper-deficient plants are more vulnerable to diseases and may experience increased fungal and bacterial infections.

Copper deficiency symptoms in Arabica coffee crop. (Photo courtesy of ICL Brazil)

Copper deficiency symptoms in Conilon coffee crop. (Photo courtesy of ICL Brazil)

How should you manage copper deficiency?

1. Soil Testing: Begin by conducting a soil test to determine the copper content in your soil. This will help you identify whether there is a deficiency and, if so, its severity.
2. Fertilization: If a copper deficiency is confirmed, you can manage it by applying copper-containing fertilizers. However, it’s essential to follow recommended application rates to avoid toxicity, as excessive copper can harm plants.
3. Organic Matter: Improve soil organic matter content, as organic matter can help increase the availability of copper to plants.
4. pH adjustment: Check and adjust the pH of the soil if it is too alkaline. Copper availability decreases in alkaline soils, so lowering the pH can improve copper uptake by plants.
5. Crop rotation: If possible, practice crop rotation to reduce the risk of disease in copper-deficient plants.
6. Preventive measures: To prevent copper deficiency in the long term, maintain good soil health through proper crop rotation, organic matter additions, and regular soil testing to monitor nutrient levels.

It’s essential to monitor the progress of treatment and adjust copper applications as needed to ensure that the deficiency is corrected without causing toxicity. Always follow recommended guidelines for fertilization and consult with local agricultural extension services or experts for specific recommendations based on your crop and soil conditions.

Which soils are prone to copper defficiency?

Soils prone to copper deficiency typically have certain characteristics that limit the availability of copper to plants. These include:

1. Sandy soils: These soils have low organic matter and poor nutrient retention, making copper less available to plants.
2. High pH soils: Alkaline soils (pH above 7.5) tend to bind copper tightly, reducing its availability.
3. High organic matter soils: Peat soils with high organic matter content can bind copper, making it less accessible to plants.
4. Soils with high phosphorus levels: Excess phosphorus can interfere with copper uptake, leading to deficiencies.

Copper deficiency symptoms in soya crop. (Photo courtesy of ICL Brazil)

Addressing Copper Deficiency

Early interventions can prevent more severe problems. As soon as you detect copper deficiency in your crops, it is advisable to act quickly to mitigate the symptoms and restore healthy growth. Farmers can address copper deficiency in crops through several methods, including soil application, foliar sprays, and fertigation:

1. Foliar fertilization: application of a copper-containing spray allows a quicker uptake by the plant than from soil. Foliar application can be particularly effective for addressing acute deficiencies.
2. Soil fertilization: it is recommended to apply dry granular NPK fertilizers containing copper to ensure even distribution across the field. For best results, incorporate the fertilizer in the upper soil profile to make it more accessible to plant roots.
3. Fertigation: copper can be supplied to plants also through irrigation by using a soluble copper fertilizer which can easily dissolve in water.

Copper deficiency symptoms in maize crop. (Photo courtesy of ICL Brazil)

Which ICL fertilizers supply copper?

Fertilizers containing copper are essential for preventing copper deficiency in crops, ensuring optimal plant growth and enhancing overall agricultural productivity. ICL fertilizers contain chelated copper, which is highly effective in preventing copper deficiency, especially in soils with high pH where copper availability is low. Chelated forms are preferable as they less likely to cause toxicity. Some of the ICL fertilizers that supply copper include:

Foliar Fertilizers:

• Agroleaf® Foliar Line: Fully water-soluble NPK formulations with micronutrients, including chelated copper.
• Nutrivant Foliar Line: Some of these fully soluble foliar NPK formulations are enriched with copper, like Nutrivant Tomato. This line features Fertivant technology to improve penetration and retention, thus enhancing crop yield and quality.

Water Soluble Fertilizers for Fertigation:

Most of ICL’s water soluble fertilizers contain copper and other micronutrients for full nutrition of crops through fertigation systems. Some examples are:

• Agrolution® Liquid ME-6: This liquid specially-designed formula is rich in EDTA-chelated copper, manganese, iron, and zinc, along with added mineral-form molybdenum and boron. Ideal for fertigation of all crop types to prevent or correct nutrient deficiencies.
• Solinure®: A water-soluble NPK fertilizer line with micronutrients, including copper, designed for fertigation of field or greenhouse fruit and vegetable crops.
• Agrolution® Special: NPK water-soluble fertilizers enriched with micronutrients package, including copper. The acidifying effects of these formulations make more nutrients available to crops.

Granular Fertilizers for Soil Application:

• Agroblen Tablets®: Agroblen® Tablet is a 100% coated NPK-based fertilizer enriched with magnesium and micronutrients, including copper, perfect for application in planting holes. It features patented Resin Release Technology for simultaneous N, P and K release, precision nutrition supply and efficient uptake.

• ICL PKpluS®: A line of PK (phosphorus and potassium) granulated fertilizers based on Polysulphate, containing five nutrients in a single granule: phosphorus, potassium, sulfur, magnesium, and calcium. Tailor-made formulae with additional micronutrients, including copper, are available upon request.