What is Cation Exchange Capacity (CEC) Number in soil, and Why is it Important?

What is Cation Exchange Capacity (CEC) Number in soil and Why it’s Important?

Cation Exchange Capacity, or the CEC #, is a measurement of the soil’s ability to hold positively charged ions. Cations are positive ions, and anions are negatively charged ions. There are plenty of positively charged ions in the periodic table, but to get the most out of your soil, there are certain elements that you want to ensure are in the right ratio. Their primary uses are to offer the proper requirements for the proper growth and development of any root system.

What Soil Nutrients Are Needed For Optimal Plant Growth

There are two main types of nutrients that are needed for proper plant growth: macronutrients and micronutrients. Macronutrients are needed for the majority of healthy plant growth. Micronutrients are made up of less than 1% of the plant’s ecosystem but are critical in helping plants complete their full lifecycle.

What Are The most Important Cations for Plant Growth?

Nitrogen (N)
- It is important for plant growth (structure), plant food processing, and the creation of chlorophyll. Without proper amounts of nitrogen, plant growth will be limited. Due to the limited size of plant growth, you will not be able to see your plants grow to their full potential.
Phosphorus (P)
- This nutrient is extremely important for root growth and winter hardiness. Without proper rooting, your plant can be subject to blowing over in strong winds. Winter hardiness is important for plants that thrive in cool weather or need sustained nutrients to get through the cold and into the next growing season. On top of all of this, phosphorus will quickly help your plants reach maturity.
Potassium (K)
- Potassium helps your plants grow their roots and be resistant to droughts. Think of it like this: no quality roots, no drought resistance. Essentially, you need potassium to help your plants grow no matter what weather may come.
Calcium (Ca)
- Calcium helps to build strong plants at the cellular level. The proper amounts of calcium in the soil will help strengthen the cell walls of your plant. Just like in people, calcium helps build strong bones; calcium helps build strong plants.
Magnesium (Mg)
- Having the right amount of Magnesium is central to chlorophyll molecules. Without chlorophyll photosynthesis cannot properly take place. Ultimately, this will result in lower quality plant growth and formation.
Boron (B)
- To have the cell wall form properly, you need the right amount of boron. Having this proper amount of boron in the soil will provide the proper maintenance of structural and functional integrity in biological membranes. This allows for proper movement of sugar (energy) into the growing part of the plant, thus allowing proper pollination and proper seed set production.
Copper (Cu)
- Copper is required for many enzymatic activities in plants, including chlorophyll formation and seed production. These enzymes are used as biological catalysts. Catalysis are used to reduce activation energy, thus allowing reactions for activities in plant growth to occur easily.
Iron (Fe)
- Iron is integral to the synthesis of chlorophyll and is essential in the maintenance of chloroplast structure and function. Without Chloroplast, the photosynthetic process of turning light energy into chemical energy cannot occur properly, leaving you with sad plants.
Manganese (Mn)
- Manganese sustains the metabolic roles within different plant cell compartments. These metabolic roles include pathways for protecting themselves against droughts, pests, and herbivores. Without the proper level of manganese, the beauty of the flowers, as well as pollination production, is severely diminished.

What Does It Mean If I have Low CEC numbers ?

The gist is that Low CEC Numbers will struggle to support turf grass, let alone any other plant life. Here are some recommended ranges for most people.

Regarding lawns and turf grasses, the ideal range for the CEC# is between 15 and 25. Any soil with a CEC# under 15 can be considered deficient, and when the CEC# is less than 5, it can be considered “extremely poor”.

If a soil test is taken and your CEC number is low, aka, near 5, the microbes in your soil cannot deliver the needed nutrients with the efficiencies they should. Meaning that any nutrients placed in the soil are being lost. Leaving your leaves, lawns, and landscaping looking very deficient and unhealthy.

What Classifications Are Used for Measuring CEC Soil Health?

Sand – typically carries the lowest CEC# CEC Readings anywhere from 3 to 5 all the way to 10.
Silt – typically carries higher numbers than sand but lower than clay-based soils.
These CEC readings will be in the 15 to 20 range, with loams making up the 10 to 15 CEC readings range.
Clay – Will usually carry the highest CEC #’s commonly found in most soils.
Clay and Clay Loam soils will usually read CEC#’s of anywhere from 25 to 50.
Organic Soils – The best Organic Soils will return CEC numbers anywhere from 50 to 100.
These readings mean that these are some of the healthiest soils.

How To test For Your CEC number?

Some, but not all, Soil test kits report CEC numbers, so it’s important to make sure that they will be reported before purchasing soil testing kits.

We recommend using SoilKit.com. They have easy-to-read results and step-by-step instructions. There, you can purchase just one or a two-pack to see how microbes and other additions have changed things.

And a pro-pack for contractors and landscapers who want to give their customers data like no one else can.

Additional ways to help increase your Cation Exchange Capacity naturally is by increasing organic matter in your growing areas. And by adding and rotating cover crops for fields and avoiding excessive tillage practices.

How Can I Fix A Low CEC Number?

Before Soil Care

After Soil Care

Adding Soil Microbes to your ecosystem’s environment is one of the best ways to increase your CEC Number.

Soil Microbes carry a negative charge, and the majority of macro and micronutrients carry a positive charge. Thus, the negatively charged microbes can carry the positively charged nutrients (cations) to your plants and grasses.

As Dr. James White has put it, “Microbes are what carry the soil nutrients through the root system through a process called the Rhizophagy Cycle”.
The Rhyzophagy cycle is where soil microbes alternate between living in the free soil phase and obtaining nutrients for plants by delivering them through their root structures.

The microbes are the organisms that help gain nutrients from surrounding soils. If a plant doesn’t need to work as hard to collect essential nutrients, it can put more energy into building stronger cell walls, bigger flowers, vegetables, etc.

What benefits Do Microbes provide to their environments:

Decomposes organic matter into a rich carbon source
Unleashing aggregate-bound phosphorus
Improve nitrogen fixation
Breaking down of heavy metals & chemical contaminants
Reduce salinity (saltiness) within the soil
Oxygenates soil and plant roots
Increase water retention
Release constricted nutrients
Improve fertilizer efficiency
Enhance root development
Reduce hardpan and crusting
Inhibits soil-borne pathogens
Balancing of the soil ecosystem

What Should My Soils CEC Numbers be:

The Ideal range of Cation Exchange Capacity (CEC) number is between 15 and 25. This means that all of your Macro and Micronutrients are being utilized and delivered in the soil efficiently. This means that your lawn, gardens, and landscape will be more beautiful and more low maintenance than ever before.

With Soil health improved and dialed in, and in the proper CEC number range. With the proper level of nutrients, you will save time and money on fertilizers, pesticides, and water!

If you want to learn more, visit our Soil Microbes page, Contact us directly, call over the phone, or visit us in person at Sauders Hardscape Supply.

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