Calcium For Plants: How Important And Beneficial Is Calcium

All living things need calcium, yet even though calcium is an abundant mineral, it often comes in a form not easily absorbed by consumers. This same goes with plants.

Although a bit of calcium exist in quality gardening soils, it is very often not “bioavailable” to the plants growing there. What can you do to ensure that your plants contract plenty of calcium from the soil?

suppling calcium for plants using eggshells

In this article, we will discuss various calcium sources and explain the ways in which calcium can affect plants. We will also present some sound advice about soil amendments supporting efficient delivery of calcium. Read on to learn more.

Table Of Contents

You Can Find Calcium Everywhere

Calcium exist in great amounts in different places. In fact, it is the fifth most abundant element. It is typically sourced as a mineral in gypsum, dolomite, and calcite. It is copious in sedimentary rocks such as limestone and marble.

Calcium also appears in multiple compounds. Some of the most common include:

  • Lime – Calcium Carbonate
  • Plaster of Paris – Calcium Sulfate
  • Various Fertilizers – Calcium Phosphate
  • Vitamin Supplements – Calcium Gluconate
  • Substances for Ice Removal – Calcium Chloride

Although calcium comes profuse in many forms, not all can be absorbed by people, animals, and plants.

How Calcium Affects The Soil

For plants to be healthy, they must have the basic element, calcium. This naturally occurring element is frequently used as a soil modification for altering pH levels. When calcium is added to the soil, it works in combination with other elements to create a variety of chemicals, all of which affect other chemical interactions. One common use of calcium is the mitigation of damage that is caused by fertilizer overuse. [source]

Some Fertilizers Include Calcium As A Buffer

There are several ways in which soil pH is affected by the addition of calcium. Soil that has high calcium content usually has an alkaline pH. Those possessing low calcium content are generally acidic. Alkaline soils with a pH value of 7.2 or higher cannot absorb calcium.

When this is the case, the excess calcium in the soil becomes combined with other elements and creates insoluble compounds.

Plants cannot absorb these compounds. Furthermore, plants can restrict and regulate intake of calcium to a narrow range. This function limits the amount of benefit a plant can glean from increased levels of calcium in soil. [source]

Calcium & Chemical Interactions

When there is more calcium than can be absorbed in the soil, the excess combines with other elements and creates insoluble compounds. This results in a restriction of the availability of elements, such as iron, boron, and phosphorous, that are necessary for plants to thrive. Additionally, any of the following elements in excess can inhibit calcium absorption:

  • Potassium
  • Sodium
  • Ammonium
  • Magnesium
  • Aluminum
  • Ammonium

Potassium, calcium and magnesium should co-exist in adequate proportions. An excess of any of these nutrients would dissolve others resulting to either calcium or magnesium deficiency and more.

Calcium, as an acidic element may be compounded with other elements to reduces its acidity before it gets mixed with the soil. This process is known as liming.

The combination of calcium and cal-mag supplements make a good liming material which comes in different forms such as the crystalline calcium carbonates, also known as the calcitic limestone. On the other hand, crystalline calcium-magnesium is commonly known as dolomite lime.

The Solubility Of Calcium

When soil is very acidic, with a pH level of 7 or below, cations (combinations of positive ions) of aluminum and iron have greater solubility. This results in restricted calcium absorption as these ions combine with calcium molecules in the soil.

This is damaging because acidic soil generally has very low calcium levels. Interference by aluminum and iron cations only worsens this problem. An effective solution is to add gypsum or calcium carbonate to the soil. This will increase both the calcium level and the pH level of the soil, making more calcium available for plants.

Solubility Of Alkaline Substances

If soil pH levels are high, excess calcium becomes combined with other chemicals that may be present. For example, calcium frequently combines with boron and phosphorous. This hampers plants from being able to absorb these elements.

If there is too much boron or phosphorous in soil, plants may suffer from discolored leaves and stunted growth. It is possible for boron and phosphorous to reach toxic levels in soil. When this is the case, an application of calcium can help prevent damage to plants.

How Does Calcium Help Plants?

Just as calcium helps people and animals build and maintain strong bones and teeth, it helps plants build and maintain strong cell walls. Therefore, it is so important for quality, nutritious soil to be rich in calcium balanced properly with other elements – both biotic and abiotic.

Abiotic elements are non-living elements in an environment (e.g. sun, wind, and rain). These must be considered when determining the nutritional value of soil. For example, rain/water is vital in the process of calcium uptake because sufficient water is necessary to carry calcium throughout the plant to provide nutrition.

If a plant receives too little water, it will also receive too little calcium. For this reason, if your plants are showing signs of calcium deficiency, you should first examine your watering schedule. If it seems your plants are adequately watered, examine the condition of your soil and determine the steps needed to increase the availability of calcium to your plants.

Calcium Delivers Vital Nutrition

In addition to building strong cell walls to help your plants stand up straight and tall, calcium also carries other nutrients along with it by binding to them. Additionally, it acts to counteract organic acids and alkali salts in the soil. In short, calcium is a very important vitamin supplement for your garden.

If your plants are deprived of calcium, they will suffer from growth problems. Furthermore, leaves may wither and turn brown. In tomato and pepper plants, this will manifest as blossom-end rot. [source]

Other possible victims of blossom end rot due to lack of calcium include squash, cucumber, and melon fruits. You can stop the blossom end rot by applying foliar spray or giving the plant a correct nutrient solution.

In celery, you will see “black heart.” In cabbage, calcium deficiency results in internal tip burn.

What Can You Do To Increase Calcium Availability?

Lime is an excellent supplement that will help raise calcium levels in soil. You can also add eggshells to your compost heap to increase calcium content. Want big, tasty tomatoes? Crushed eggshells planted with your tomato seedlings will give them a boost of calcium.

Some gardeners use half eggshells as starter cups for their seeds. This is easy to do. Just place the half eggshells in an egg carton, add a bit of potting soil, and plant your seeds. Water as usual. Transferring your seedlings in eggshells to your garden is very simple. Just lift the shell from the carton, crush it just a bit, and plant it for beautiful, healthy tomato plants!

Calcium Can Be Absorbed Through Leaves

If you see signs of calcium deficiency in mature plants, you can boost calcium levels by spraying a calcium solution directly onto the plant. Calcium can be absorbed through the plant’s leaves.

To use the foliar feeding method, mix a solution using a gallon of water and half an ounce or a full ounce of calcium nitrate or calcium chloride. Spray this solution evenly over your plants. Take special care to be sure that new growth is well saturated.

Calcium Is A Universal Necessity

It’s easy to see that proper calcium levels are essential to a healthy, thriving garden. Follow the advice presented here to make sure your plants are getting the proper dose of calcium and all the benefits it provides.

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