On the soil:

Cu is an element that has a low solubility at high pH; but it has a great tendency to form complexes with the organic matter of the soil, which is a factor that explains why the Cu deficiencies are lower than those of Zn in high pH soils.

In the soil, the content of Cu varies between 3 to 100 ppm, being especially relevant to know what part is present in the minerals, in organic compounds, on the interchangeable soil colloids, and soluble in it.

The mobility of Cu is very limited due to the great adsorption made by the surface of the soil change; however, the great tendency of the Cu to make complexes with the organic matter of the soil is an important factor that explains why the deficiencies of Cu are smaller than those of Zn.

In the plant:

• Cu deficiencies are usually observed in high pH soils, but also in heavily washed acids.
• The contents in Cu of the plants are between 2 and 20 ppm. Cu is absorbed by the plant in minimal quantities and is almost completely in complex form in the environment of the root; but before absorption it dissociates from the chelate; that is, it implies the movement of the ion in the plant.
• Compete with Zn for the same places of root absorption, it is antagonistic, but not with Mn.
• Mobility is quite restricted, but young women can be given old leaves.

The Cu is presented in the xylem and the phloem probably in bound form with amino acids due to the affinity of the Cu with the N atom of the amino acid groups.

The Cu presents a mobility dependent on the concentration of the same in the plant; in young wheat plants, fed correctly with Cu; the displacement of this to the grain is done correctly, not being

so if the level of this element in the plant was deficient.

Foliar applications of copper compounds for fungicidal purposes are capable of correcting Cu deficiencies; which shows the movement of this in sprays.

Physiology:

In leaves, about 70% of Cu is in chloroplasts, in protein forms. It also participates in Hill’s reaction and in the development of chloroplasts.

There are also numerous enzymes that contain Cu; some of them are involved in the respiration of many plant tissues.

Involved in the symbiotic fixation of N.

It also participates in protein biosynthesis.

In summary, Cu deficiencies affect numerous biological processes, including:

1. Metabolism of carbohydrates (photosynthesis and respiration).
2. N metabolism (N fixation, synthesis and protein degradation).
3. Metabolism of cell walls (in particular, the synthesis of lignin).

The Cu also intervenes in the viability of pollen and in resistance to diseases.

The Cu in the nutrition and fertilization of crops:

Cu deficiencies: although the needs or extractions of Cu are very low (approximately 25 to 150 g / Ha); Insufficient nutrition can limit yields under certain soil conditions and in certain particularly sensitive crops.

• Environmental conditions favorable to deficiencies in Cu: poor mineral predisposition (eg granites), high soil pH and interactions with other fertilizing elements. In general, soils rich in N and in P can induce Cu deficiency by increasing the needs of Cu due to better protein synthesis.
• High applications of Zn can aggravate cupric deficiency (root competition).
• They can be cited as soils especially prone to copper deficiencies:
  • Poor, heavily washed soils, such as sandy pods.
  • Very turbid, poor soils with very high pH.

The crops most sensitive to copper deficiencies are wheat, barley, oats, gene. Citrus, carrot, spinach, lettuce, beet, especially winter cereals.

Among the horticultural crops, spinach and pea.

The most typical signs of Cu deficiency are observed in cereals such as whitish discoloration of the tips of the younger leaves, including deficiencies in the spike that can produce “empty spikes”. In corn; the final leaves lose turgor and bend, remaining stuck in the shape of a handle.

In fruit trees, necrosis of the tips and edges of the younger leaves.

In general, the symptoms are seen in the newly formed tissues.

Symptoms of toxicity are very rare, only mentioning the cases of soil conditions prone to keep Cu permanently available and very repetitive foliar treatments with this element.