This is a complicated subject, and we don’t claim to be experts, but here is a quick and dirty explanation.
A soil’s ability to react with positively charged molecules is called it’s cation exchange capacity (CEC). The higher the CEC, the higher the negative charge of the soil and the more cations that can be held. The most common soil cations are: calcium, magnesium, potassium, ammonium, hydrogen and sodium.
Generally soils with more clay silt and organic matter have a higher CEC and the CEC decreases with increased sand content.
The most basic thing to remember is CEC indicates how well your soil will hold onto anything, including nutrients and water.
Below are some practical implications of your soil’s Cation Exchange Capacity:
- Low CEC soils need quick but frequent waterings, while high CEC soils need slow water applyed less often.
- When applying fertilizers and soil conditioners to low CEC soil, it is best to apply a little at a time to avoid the risk of leaching them through the soil and into ground water.
- When applying nutrients to high CEC soils it is best to incorporate them, if they are placed on the surface they are more prone to run-off due to the slow infiltration rate.
- The lower the CEC of a soil, the faster the soil pH will decrease with time.
- Soils with a low CEC are more likely to develop deficiencies in calcium, potassium & magnesium.
- Because they are resistant to leaching, high-CEC soils generally do not need to be limed as frequently as low-CEC soils; but when they do become acid and require liming, higher lime rates are needed to reach optimum pH.
How do I increase my CEC?
Depending on the scale of your growing operation this can be a difficult task.
For smaller areas compost, worm castings and biochar are a great ways to add organic matter and increase your CEC.
If you are dealing with large fields realistically your best approach would be to adjust your management to account for the low CEC according to the implications outlined above.\
Sources:
https://www.extension.purdue.edu/extmedia/ay/ay-238.html
http://nmsp.cals.cornell.edu/publications/factsheets/factsheet22.pdf
http://msue.anr.msu.edu/news/what_is_your_soil_cation_exchange_capacity
you did not fully explain the importance cation exchange capacity
Please jump in and share your ideas. How would you explain the importance of cation exchange?
~Walt
cation exchange capacity simply talks about how well colloidal materials of soils are able to give off the ions surrounding their negatively charged surface for other highly positively charged ions from a solution system that these particles swims in. the importance of this phenomenon is seen in
1. fertilizer application and nutrient retention. soils are able to retain ions because of the high adsorptive affinity of its particle with the increase in ions due to fertilizer application. these strong adherence of the ions in some way also prevents leaching.
2. plant nutrient uptake. adsorped cations or minerals by soils are made available to plant root through and exchange mechanism with the floated hydrogen ions on the root surface.
3. soil fertility or pH correction. highly acidic soils ie. soils with a lot of Al ions on its surface may treated with lime to reduce its pH level. an ion exchange process also goes into this reaction. calcium carbonate ie. the transformed form of lime in contact with soil complex exchanges its calcium ions with the that of Al of the soil thereby reducing the soil acidity considerably.
thanks
1.knowing the CEC of the soil helps in determining the required type of fertilizer nutrients to be applied during planting.
2.CEC also determines the pH of the soil,hence appropriate technique to buffer it is realised hence ensuring maximum crop production.
3.CEC determines the appropriate type of crop to be grown,this is by examining the pH value of the soil ie crops doing well in acidic soils requires high cec content.
What is the optimum CEC level? Does it varies from a crop to the others?
what are factors that affect CEC
Soil pH
Organic matter
Type of soil colliods
Are the factors which effect the CEC
Nature of the soil particas i.e if is sand or clay silt
Soil pH
Type of clay
Soil texture
Humus
How is cec useful in the purification of ground water?
Hi!
This is interesting topic, and I like how people add information on the comment section. It is really great to find blogs like this.
Keep it up!
-Ron