Copper is obtained mainly from ores. The main forms are copper pyrites, copper glance and copper shale.
Pure copper is shiny reddish brown in colour. Exposed to air, over time the surface oxidises to a dull, dark brown protective layer. This is caused by the interaction of carbon dioxide and oxygen with copper in humid surroundings. This process makes the metal to a large extent resistant to the influence of weather. In higher concentrations the oxidised layer can develop a bright green appearance, the so-called patina.
Copper and growth
Copper is absolutely necessary for normal, healthy growth and for the reproduction of all plants and animals.
The consequences of copper deficiency reach from decrease in production to 20% – which might result in the case of many useful plants as consequence of a hidden lack of copper, without any visible symptoms – up to the complete loss of the harvest.
Lack of copper was observed in the whole world and in all climate zones where useful plants are cultivated. The occurrence of lack of copper varies with the soil and the cultivated plants. A lack can occur particularly with plants, which are cultivated on sandy soils, on soils with a high quota of organic substance and also on lime soils.
Biological systems use the ability of copper
- To absorb electrons, to transfer and thus take part in oxidation/reduction reactions
- To form complexes together with organic compounds. Sometimes if these metabolic pathways are interrupted as consequence of a lack of copper or also a surplus, then growth, yield and quality are impaired.
Copper in the soil
The total copper content of the soils consists of 5 factors:
- Soluble forms in the soil solution – are immediately available to plants
- Stable, organic complex connections in the humus – not available to plants
- The copper absorbed through hydroxides of the manganese and iron
- The copper absorbed in the clay humus complex
- The copper bound in the crystal lattices of the soil minerals – only becomes free when the weathering occurs
The total quantity on water-soluble and exchangeable copper is often very small, although the total concentration of copper in the soil could be called sufficient (over 10 mg/kg with mineral soils and over 30 mg/kg with organic soils).
The raw material of a soil can vary substantially when it comes to copper content, whereby normally dark slates exhibit high concentration and sandstones low concentration.
The availability of copper for an absorption by plants is mainly determined by the pH value of the soil, by its share of organic substance and also by its sorption capacity.
Typical soils which lack copper are mainly sandy soils, peat, soils with more than 7 to 10 % organic substance as well as lime soils.
The total copper content and the content of available copper in the soil can considerably differ sporadically.
In gardening culture substrates with high shares of peat and in pure peat culture substrates, sufficient copper supply comes to a meaning which may not be underestimated.
Lack of copper has been reported on over 50 plant types and in 51 countries.
Copper in the nutrition of plants
The existence of latent lacks, whereby the harvest yields are decreased, without the appearance of clear symptoms, will be illustrated with the following significant increased yield enhancements caused by copper, which were obtained during repeated field tests:
– crop enhancement around 22,4 % with summer barley on brown earth with sand-like texture
– crop enhancement around 13,5 % with winter wheat on Mullrendzina
– crop enhancement 18 % with sugar beets on brown earth with sand-like texture
– high-significant harvest increment with Gerbera in peat
In addition to the decrease in production, copper deficiency can affect the quality of many cultivated plants.
Examples of quality reductions caused by lack of copper are:
– citrus’s, less appealing appearance, reduced fruit size
– onions, spongy and with faded colour
– carrots, faded colour
– salad, faded colour and wilted
– pears, cork formation and cork blotches
Copper in the metabolism of the plant
Copper is a component of different enzymes and other proteins, where it mainly causes the electron transfer in crucial metabolic pathways. As by other trace elements the metabolic processes are disturbed both by the lack or surplus of copper.
Photosynthesis, respiration, reproduction, protein formation, lignification, auxin regulation, resilience against diseases and other functions of the plants can be affected by lack of copper.
The assimilation of copper over the root can be reduced by relatively high calcium, potassium and ammonium ions concentrations.
Strong nitrogen fertilisation delays the ageing of the leaves and reduces the copper quantity, which can be distributed on young texture.
Various vegetables that are cultivated in the whole world are highly sensitive to lack of copper.
If copper accumulates itself in the soil, in the course of many years as consequence of emissions, sometimes then fito-toxicity arises; this can however usually be repaired through limes.
Symptoms of copper deficiency
Lack of copper impairs the lignification and thus leads to the collapse of the texture, in particular with young leaves, which first look as if they withered and later become necrotic.
Leaves are frequently rotated and distorted.
Copper is normally displaced by old on new texture only in limited extent. Symptoms usually show up first on young texture.
- salad, the leaves lack the firmness, they look like rabbit ears, young leaves curve in the shape of a key
- spinach, the edges of the young leaves, which have a dirty color, whiter and unroll themselves
- tomatoes, leaves and stems lack the firmness, leaves are small, hard and furled, the pinnate leave branches are curved downwards in the typical way
- onions, the points of the youngest leaves first become chlorotic and then white, they rotate on a spiral or turn themselves in such a way that they stand orthogonally to the plant, the onionskins are thin and pale yellow Excerpt from the DKI technical book “Copper in the agriculture” Publisher: German Copper-Institute
The expenditure for original appeared under the title “Copper in Plant, Animal and Human Nutrition”, text by Dr. V.M. Shorrocks and Dr. B. J. Alloway
The copper tools project
From his understandings of the ways of living Nature and his experience as an engineer, Viktor came to the assessment that cultivating the soil with copper implements would be more beneficial to the Earth and lead to healthier plants. In his writings, he listed several reasons for this.
Primarily, he believed that using iron or steel implements to work the soil was detrimental. Everything in Nature is in movement, moving towards either growth or decay. If metallic iron is exposed to the weather it will rust and decay in a relatively short time. He could not see the logic of trying to encourage plants to grow using a material that is in a process of decay. Copper, on the other hand, is much more stable. Nuggets of metallic copper have been found in the Earth. It is not antagonistic to the Earth, is not in a process of decay. (In fact, it actively resists harmful bacteria. More about this on the copper page of this site.)
Secondly, he believed that on planet Earth, growth occurs in cooling conditions, in the medium of water; and decay occurs in conditions of warmth: the medium of fire. That is why compost heaps get hot. The heat encourages the constituents of the heap to break down, to be accessible for the next cycle of growth. Iron has greater frictional resistance than copper. This means that as an iron or steel ploughshare is dragged through the soil it heats up. Copper and its alloy, bronze, are smoother than iron, so the tool stays cool as it moves through the soil.
And thirdly, iron is a sparking metal. A spark is a discharge, a loss of energy. Viktor Schauberger believed that as the groundwater makes its way to the surface, it acquires a weak electrical charge. This charge is part of what nourishes the plants. Using iron tools depletes the groundwater of this charge, leaving less for the plants. Copper is a non-sparking metal, so there is no loss of energy in this way.
In the late nineteen-forties he collaborated with an academic from Salzburg to institute some field trials to test this idea. They grew a range of eight crops over fourteen trials, cultivating each test plot half with a copper-plated plough and half with a conventional steel plough as a control. The results were consistent. The crops cultivated with the plough with copper ploughshares had larger, healthier yields and fewer pests.
Despite the success of the trials, for various reasons he was not able to go into commercial production. However, his family kept his ideas alive and in the late 1990’s a coppersmith was invited to develop a range of garden tools, inspired by Viktor Schauberger’s work nearly half a century previously.
Johannes Stadler / PKS Bronze was startet to manufacturing the copper garden tools.