Why Do Plants Need Copper? A Fundamental Micronutrient

Plants absorb many elements from their surroundings. Other than carbon, hydrogen, and oxygen, which they receive from air and water, there are also 13 additional nutrients they uptake from the soil. Plant guides and gardening blogs keep emphasizing the need for nutrient-rich soil for plant growth. Copper is one such nutrient that plants take from the ground.

Why do plants need copper, and how can you ensure enough is available to the roots for absorption? But, first, let’s dive deeper into the role of this fundamental micronutrient and understand how it affects your plants. You’ll also learn how to deal with copper deficiency and toxicity in plants.

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The Types Of Plant Nutrients

Plant nutrients fall into three categories based on the amounts the plant needs them. Some nutrients are required in large quantities, and these are called macronutrients. Those needed in moderate quantities are called secondary nutrients.

The third category is micronutrients. Though they are just as essential for plant growth as macronutrients and secondary nutrients, they’re typically only needed in small quantities.

Copper falls into the third category. Copper is an essential micronutrient for plants, and even though they don’t need much of it, its deficiency can cause problems. When you read further, you’ll see how plants use copper for growth and how you can ensure its correct availability to the plant roots.

How The Plants Use Copper?

Copper is vital for plant growth. It takes part in the formation of chlorophyll and plays a crucial role in multiple enzyme processes. Although it’s only needed in small traces, its inadequacy can result in several problems. Here are some of the essential functions copper has in plant growth:

  • It’s a critical element of several enzymes that contribute to plant processes.
  • It also plays a role in the metabolism of carbohydrates and proteins in plants.
  • It’s present in plant cell walls that contribute to the overall strength of the plant.
  • It helps form chlorophyll to facilitate photosynthesis, whereby plants make their food.
  • It’s essential for plants’ respiration, which uses glucose and oxygen to produce energy for growth.
  • Copper activates the enzymes that contribute to the synthesis of lignin, a polymer that forms the plants’ support tissues’ structural material.
  • If you’re growing edibles, the right copper levels in the soil will ensure the best flavor and storage life of produce.

So now you see why plants need copper? With an extensive list of functions, copper’s importance for plant growth cannot be overlooked. Without ample copper in the soil, plants won’t grow properly. But, an excess of copper in the ground isn’t good either. So, ensure your plants are getting all the copper they need to grow, but not too much of it!

How Much Copper Should Be In The Soil?

Copper is naturally present in the soil in different forms. In mineral soils with loamy or clayey texture, typical of most gardens, copper concentration can range between 10 to 200 parts per million. Organic soils also have similar levels of copper. In sandy soils, it’s usually between 1 to 30 ppm.

Copper deficiency is common in sandy soils. You can resolve this by applying fertilizers rich in copper sulfate (usually 30 pounds of copper sulfate for each ton of fertilizer) multiple times per year.

Plant tissues comprise about 8 to 20 parts per million copper. If the copper concentration is less than five ppm in leaves, the plant may show deficiency symptoms. If it’s lower than four ppm in plant tissues, you’re likely to observe severe deficiency symptoms.

Copper Deficiency In Plants

So you have an idea about why do plants need copper. When copper concentrations in the soil are lower than required, plants may experience copper deficiencies. Though it isn’t a common problem, it may occur in certain conditions. As we mentioned earlier, it’s more likely to appear in plants growing in sandy, alkaline soils.

What Causes A Copper Deficiency In Plants?

If the plants show deficiency symptoms, it doesn’t always mean that the soil lacks copper, though it may be one reason. Several other factors can inhibit the availability of copper to roots. Here are some of them:

  • Copper availability is lower in alkaline soils.
  • Waterlogged soils can reduce the availability of copper.
  • An excess of nitrogen, phosphorus, zinc, and other nutrients can reduce copper’s uptake by the plant roots.
  • An excess of organic matter can also reduce the uptake of copper. But, once the organic matter has sufficiently decomposed, ample amounts of copper will be available for absorption by the plants.
  • Sometimes, the soil may naturally lack copper. For example, sandy soils have low concentrations of copper and may need amendments.

What Are The Symptoms Of Copper Deficiency In Plants?

Copper deficiency symptoms vary in different kinds of plants. Stunted growth, delayed flowering, and sterility are common symptoms of a deficiency. Seeds extracted from a copper-deficient plant will have a low germination rate. The lack of it may also appear as wilting of the leaves, with the tips turning bluish-green.

Since copper is immobile, the symptoms will typically hit new growth. Slight chlorosis of the entire leaf or between veins can also be linked to the same problem. As a result, the flower color will often be lighter than usual in such plants.

How Do You Treat Copper Deficiency In Plants?

Copper application may seem the only solution to the problem, but it’s not always the case. If you notice deficiency symptoms, the first thing you should do is check the soil pH. Copper uptake is highest when the pH is between 5.5 to 6.5, and the soil isn’t waterlogged. Next, add more organic matter to make copper and other nutrients adequately available after decomposition.

If the symptoms persist, get a soil test to check the copper concentrations. You can further confirm the deficiency by testing the plant tissues. When you use both these tests in combination, you’ll know what’s wrong and how to fix it.

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If copper is low in your soil, copper fertilizers containing copper sulfate or copper oxide are available for foliar spray and soil applications. But remember to avoid excessive application since it can cause toxicity.

Copper Toxicity In Plants

Too much copper isn’t good either. High levels of it can even poison the plants! So one of the first chemical controls for weed was a 5% solution of copper sulfate!

So, YES, copper toxicity is a thing, and as they say, too much of a good thing isn’t always good. It may be an essential micronutrient, but an excess amount of copper can destroy your crops.

Though it’s unlikely that copper levels are naturally high in the soil, excessive use of copper-based fungicides and industrial activities can increase those levels. As a reminder, legume crops tend to be more susceptible to copper toxicity.

What Are The Symptoms Of Too Much Copper In Soil?

High copper levels can inhibit the plant’s uptake of other nutrients, like iron and zinc. As a result, it’s common to notice deficiency symptoms from the lack of other nutrients. In addition, if copper levels are high, plant growth will slow down; leaves will initially appear bluish, followed by yellowing and browning. Copper toxicity can reduce branching and the overall development of the plant. It also lowers seed germination.

How Do You Lower Copper Levels In Soil?

When testing the leaf tissues for copper levels, it’s important to rinse them first since contaminations from fungicidal sprays can affect the test results. Sometimes, the plants may be taking up more copper than usual in soil with low pH. Make amendments to bring pH to the optimal levels.

Also, make sure not to use any copper-based amendments or sprays for treating diseases or fertilization. Instead, get a soil test to see if the concentrations of other nutrients are optimal and make amendments if necessary. Add plenty of organic matter and mulch regularly to balance the levels of nutrients available in the soil.

Final Words

Why do plants need copper? So you’re well aware of the importance of this simple element to the plants. Make sure your garden has enough copper, together with all the other essential nutrients that plants ask for.

All nutrients must be present in the ideal range for the best growth of plants and bountiful harvests. However, an excess or shortage can be problematic and will need your prompt attention if you want to save your plants from permanent damage.

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