IMPORTANCE FOR PLANT LIFE

METABOLISM

Copper plays a role in photosynthesis processes that take place mainly in chloroplasts. The first consequence of copper deficiency is a tendency toward paling (chlorosis) observed in young leaves. Copper also contributes to the formation of cell walls, particularly through lignin synthesis; therefore, a deficiency leads to a loss of flexibility and strength in plant tissues, causing a kind of “loose” structure to develop.

Copper also plays a key role in protein synthesis. Especially in cereals, deficiency manifests as whitening at the tips of young leaves (white tip disease) and empty heads at harvest (impaired fertilization). Copper excess, on the other hand, suppresses microbial activity in the root zone, inhibits root development, and may cause iron chlorosis (Fe deficiency symptoms).

From a livestock perspective, copper deficiency can cause problems such as growth disorders, infertility, pica syndrome (eating soil, stones, etc.), anemia, fading of coat color, and increased susceptibility to infections.

ABSORPTION MECHANISMS

Copper is not very mobile in soil, and only a limited portion is present in the soil solution. For this reason, the amount of copper absorbed by plants is relatively low; a significant part of the copper required by the plant depends on the availability of Cu²⁺ in the soil near the root zone.

INTERACTIONS AND SPECIFIC FEATURES

Copper availability to plants depends partly on the total copper content of the soil, partly on complexation with organic matter, and on antagonistic interactions. Especially in high-pH soils, excess molybdenum (Mo) and zinc (Zn) can compete with copper at the root uptake sites, reducing Cu uptake.

These negative interactions among trace elements must be taken into account when selecting trace-element combinations for crops, and balanced formulations should be preferred so that each element can fully realize its potential.

COPPER IN SOIL

Soils derived from granite and limestone are naturally poor in copper. High organic matter content complexes copper, immobilizes it, and reduces its availability to plants. Liming practices have a similar effect and can further restrict Cu uptake.

Especially during warm spring periods, the risk of yield loss increases when copper is a limiting nutrient, because Cu deficiency becomes more pronounced during rapid plant growth.

SENSITIVITY TABLE & SYMPTOMS

Copper deficiency is generally difficult to notice in early growth stages; symptoms typically become more evident at later stages. For example, in wheat it may appear as sterility (empty heads) during heading and fertilization stages.

Typical symptoms include a whitish color change at the tips of the youngest leaves, followed by heading disorders and empty grains. Because copper mobility within the plant is low, deficiency primarily affects newly developing tissues and becomes more pronounced in young leaves and shoots.

EXCESS & REQUIREMENT

Copper excess is particularly dangerous for sheep; the risk of toxicity is high. Even in cereals with high copper demand, excessive copper application is undesirable; especially in durum wheat, it may lead to negative effects on yield and quality.

ORIGIN & PRODUCTION

SOURCE

Copper is mostly found in igneous rocks as sulfide minerals (for example, copper sulfides). However, its concentration in rocks is generally low and is not always economically viable. Still, copper deposits have been exploited by humans for more than 4,000 years.

In plant nutrition, copper is mostly applied via foliar application to increase efficiency and manage this limited resource responsibly. In this way, sensitive crops can receive the right dose at the right time, enabling efficient use of supplied units.

FERTILIZER FORMULATION

The copper oxychloride form used in fertilizers, with its moderately concentrated structure, is considered one of the most suitable formulations both agronomically and economically for preventing deficiencies. This form provides effective copper support without causing unnecessary or potentially harmful excessive accumulation.

KEY DRIVING FACTORS

COPPER CONTENT IN SOIL

EDTA extraction is an effective method for determining plant-available Cu in the soil solution. The following threshold values can be used as a reference:

• In organic-matter-rich soils (>%2.5 OM) at least 2 ppm Cu,
• In soils with moderate organic matter (%1.8–2.5 OM) at least 1.4 ppm Cu,
• In organic-matter-poor soils (<%1.8 OM) at least 1 ppm Cu

ORGANIC MATTER

Organic matter is the main factor determining copper availability to plants. Cu is the mineral element with the highest tendency to complex with humic and fulvic acids. As organic matter increases, Cu becomes bound within organic complexes and the form directly available to the plant decreases.

TEXTURE

Coarse-textured soils with low clay and silt content—sandy soils prone to intense leaching—are sensitive to copper deficiency. Likewise, calcareous soils and high-pH, chalky profiles—especially if rich in organic matter—are prone to copper deficiency.

Organic and peaty soils are among the most problematic soil types in terms of Cu availability, because high organic matter strongly complexes copper and limits plant uptake.

CLIMATE

Dry periods reduce copper availability in the soil solution. Reduced soil moisture prevents Cu²⁺ ions from moving sufficiently in the root zone and further limits plant uptake.

pH

As soil pH increases, copper solubility decreases and the amount of Cu²⁺ in the soil solution is reduced. Nevertheless, if the soil is acidic and sandy and the risk of leaching is high, copper deficiency can also occur in such soils. In other words, there is a risk of Cu deficiency both in high-pH calcareous soils and in acidic, sandy, leaching-prone soils.