Cation Exchange Capacity (CEC) and BioChar are mentioned together in soil improvement discussions – How are they connected?
Negative & Positive Attractions
Cation Exchange Capacity (CEC) is the soil’s ability to attract, retain and exchange positively-charged cations (cat-i-on). Like a magnet’s attraction to iron, the negatively-charged soil particles will attract and hold the positively charged cations (nutrients). The strength of the attraction is described as High or Low CEC and will determine how well nutrients will linger in the soil. Plants absorb the essential nutrients in their unattached, cationic form, such as Magnesium (Mg2+) and Potassium (K+). Adding Biochar to the soil will help increase its CEC, making those essential nutrients available to soil microbes and plants.
Soils holding Hands with Nutrients
Like holding hands, either tightly (high CEC) or loosely (low CEC), soils will hold cations the same way. Cations in low CEC soil are more mobile in the “soil solution” and will have increased nutrient loss (leaching). Sandy soils tend to have low CEC and need to have nutrients and fertilizers added more often to the soil to maintain healthy plants.
Clayey soils and soils with high organic matter (OM) content tend to have a higher CEC so cations are “held tightly.” The higher CEC soils do a good job of holding onto nutrients and fertilizers (less leaching) but too much of a “good” thing can restrict the plant’s ability to accumulate the soil’s nutrients. When the soil has a healthy microbial population, then the nutrients will be processed and made available to plants naturally. Soil microorganisms are a driving force in the cycling of nutrients and an indication of healthy soil.
Biochar Encourages Improved Soil Relationships
Biochar has a high CEC because it is very porous. In fact, one cubic foot of biochar has about 300+ acres of surface area and will effectively reduce nutrient leaching. Biochar is a fixed carbon that will create a long-lasting home for microbial communities. VITAL Blend soil amendment goes a step further by combining activated biochar with freshwater-sourced humates. The added humates will stimulate the growth of soil microbes (1.) and will act as a natural surfactant, making water “wetter.” The combination makes VITAL Blend a great addition to the soil for agriculture, turf or garden and will improve the health and vitality of plants and soil.
(1.) Humic acids stimulate growth and activity of in vitro tested axenic cultures of soil autotrophic nitrifying bacteria, Vallini, G., Pera, A., Agnolucci, M. et al. Biol Fertil Soils (1997) 24: 243. https://doi.org/10.1007/s003740050238