How Do Plants Get Their Nutrients? - Cation Exchange Capacity (CEC) Explained!
Channel: Southland Organics
Date: 2023-11-16

So how DO plants get their nutrients? Check out our blog for more!
https://www.southlandorganics.com/blogs/news/how-do-plants-get-nutrients-cation-exchange-capacity-cec-explained

Cation exchange capacity (CEC) is how you measure soil's ability to hold and release various elements and compounds needed for plant nutrition. CEC has a lot to do with the nature of the various elements found in soil particles and the electrical charges they carry.
If you’re familiar with soil science, you know about cation exchange capacity (CEC). If not, it may sound like gibberish. But if you care about growing a beautiful lawn or a thriving garden, cation exchange capacity is definitely something you'll want to know about. Here's a breakdown on how you can apply this concept to improve your soil, and thus, improve plant growth.

Now that we know what a cation is, what about cation exchange capacity? Soil particles have negatively charged sites that attract and hold positively charged cations. The measurement of this is known as the cation exchange capacity (CEC). It is the measure of how many negatively charged sites are available in your soil, as determined through a soil test.

The “exchange” basically works like this: plant roots and soil microorganisms give off positively charged hydrogen ions. If these hydrogen ions can surround the nutrient cation and get closer to the negatively charged exchange site, the hydrogen ions will fill the exchange site and neutralize the charge. This frees the nutrient cation of its static bond, and it can then be taken up by a plant. 

The CEC values of soils can vary widely and be an indicator of soil fertility. Sandy soils that are low in organic matter have a low CEC, while clay soils containing a lot of organic matter have a high CEC. Typically, the more organic matter soil has, the higher its CEC. And a higher CEC means more nutrients get to your plants, which leads to lush, green lawns and thriving, productive gardens! 

Having a high CEC in your lawn or garden sounds pretty good. But how can you increase CEC to help improve your soil? One easy way is by adding humus. Humus is rich organic matter, and beneficial microbes love it. It’s naturally found in most soils, but not all soil has enough of it to keep most plants happy. You can put humus in your soil by adding organic matter and having healthy soil microbes to break it down, or add another soil that contains large amounts of humus and humic acids.

Our solution to adding humus and increasing CEC in your soil is applying naturally derived, liquid microbial products. These products, like Genesis Soil Conditioner, Omega Soil Activator, Revival Liquid Lawn Aerator and more, can be easily sprayed on your lawn and garden to increase cation exchange capacity, thus allowing your grass and plants to uptake more nutrients and be healthier. Plus, they are safe for people, pets and the planet.

The desired ratio depends on your type of soil. For instance, in a heavy clay soil, you may want 70% calcium and 10% magnesium. The ratio is tilted toward calcium to loosen up the soil. If your soil is loose and sandy, 60% calcium and 20% magnesium will help tighten up the soil and improve its ability to hold water. Notice that the total of these ratios adds up to 80%. This leaves about 20% of the CEC open for other elements. Typically about 4% would be used for potassium and 1% to 3% for sodium, leaving 4% or 5% to be filled with other bases, such as copper and zinc or iron and manganese. The remainder will be occupied by exchangeable hydrogen. This causes the pH of the soil to automatically stabilize around 6.4. This is ideal pH for organic/biological agriculture, and this is also the pH of sap in a healthy plant.

Any area that gets more rainfall tends to grow more vegetation. The portion of the soil that is made up of decaying organic matter usually increases in such areas. The breakdown of organic matter into humus is dependent on moisture, temperature and availability of oxygen. As these parameters increase, so does the rate at which organic matter breaks down. Moisture and oxygen being equal, colder upper latitudes tend to build up more organic matter in the soil than hotter southern climates. 

One extreme, for instance, is the tropics where organic matter breaks down and disappears very quickly. The opposite extreme would be the peat beds and deep muck soils found in some northern states. There are always exceptions, such as the Everglades of Florida. The lack of oxygen combined with stagnant swamp water has formed the largest peat beds in the world. Another example is the area around Sacramento, California.

We would love to help you improve your lawn and garden naturally by adding humate and increasing CEC. If you have any questions, reach out to us at success@southlandorganics.com or 800-608-3755. Don’t forget to subscribe to our YouTube channel for more helpful lawn and garden information.