# Dealing with sandy, low CEC soils



## eric1104 (Oct 13, 2020)

I've searched and read some of the other posts on the topic of sandy soils with low CEC. It appears that a remediation-style approach to correcting nutrient levels to an ideal range may not be the best approach and I wanted to start a thread directly addressing this topic.

As an example, here are my soil tests from the last 2 years. A couple pieces of background info about my inputs:


A soil texture analysis from 2021 showed it was loamy sand (82% sand; 8% silt; 10% clay).

Last year, I applied just over 5 lbs/M of P2O5 using TSP, and just over 6 lbs/M K2O using SOP. Applied in monthly doses.

I side discharge - so clippings are returned.

Foliar N through urea and AMS, PGR, and Main Event/FEature.

After adding enough K last year to theoretically raise the soil concentration to +100 ppm, it seems that my soil is not going to hold K and therefore it doesn't make sense to try to correct a deficit. What do others with similar soil types do?

2021:



2022:


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## Mightyquinn (Jan 31, 2017)

Well, I have been dealing with this for years as my CEC is 2.2 so you are way better off than I am  I have found that spoon feeding and only giving the lawn what it needs when it needs is the best way. I would recommend trying to find some Potassium Nitrate (14-0-46) and add that to the mix of Nitrogen when you spray as that will help with the grass uptaking the Potassium. With low CEC you can't really pound the soil with anything as it doesn't really hold on to it. I have seen some minor improvements in my numbers over the years but it will take a slow and steady diet approach, like most things in lawn care, it's a marathon and not a sprint.


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## Virginiagal (Apr 24, 2017)

A CEC of 11 is not a low CEC. It's a good CEC to have. Maybe something else is affecting the test result. How deep do you take your samples? Were they all at the same depth? Here's an article on potassium variability I found this morning, as your situation is interesting.
https://nutrientstewardship.org/implementation/the-highs-and-lows-of-soil-test-potassium-variability/


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## eric1104 (Oct 13, 2020)

Mightyquinn said:


> Well, I have been dealing with this for years as my CEC is 2.2 so you are way better off than I am  I have found that spoon feeding and only giving the lawn what it needs when it needs is the best way. I would recommend trying to find some Potassium Nitrate (14-0-46) and add that to the mix of Nitrogen when you spray as that will help with the grass uptaking the Potassium. With low CEC you can't really pound the soil with anything as it doesn't really hold on to it. I have seen some minor improvements in my numbers over the years but it will take a slow and steady diet approach, like most things in lawn care, it's a marathon and not a sprint.


Thanks @Mightyquinn - I suppose it's all relative! Perhaps I shouldn't think of my soil as low CEC. I appreciate the suggestion and will call around potassium nitrate - I really like the idea of spoon feeding K. Have you had any issues tank mixing with chelated iron (Feature/Main Event...I recall reading a thread where you used one of these) and/or PGR? Any thoughts on a nice rate/ratio? I have recently read to try to go 1:1 (N:K20) throughout the season for lower CEC soils, but wondering if that's practical using a urea/potassium nitrate dilution.


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## eric1104 (Oct 13, 2020)

Virginiagal said:


> A CEC of 11 is not a low CEC. It's a good CEC to have. Maybe something else is affecting the test result. How deep do you take your samples? Were they all at the same depth? Here's an article on potassium variability I found this morning, as your situation is interesting.
> https://nutrientstewardship.org/implementation/the-highs-and-lows-of-soil-test-potassium-variability/


Thanks for the input @Virginiagal! Based on my (limited) research last year, I had also concluded that a CEC in my range was good enough to remediate, but recently revisited this after failing to see a significant increase in K values year over year. In fact, when I spoke to the agronomist at Waypoint - he suggested, before I mentioned K, and only mentioning CEC, pH and Ca:Mg ratio that my soil may not hold only to nutrients well. I would like to spend more time researching Ca:Mg ratio.

I read the referenced article, and didn't see any factors that may have impacted my results relative to last year. My sampling technique was intentionally similar to last year. I sample at a depth of 4 inches (all the same, indicated by a mark on the side of the sampler). The only thing I can think of to improve my process is to take more samples. For reference, I tried to take one sample/M in random locations throughout the front/back yard.

Not to complicate the discussion, but my brother in law also applied SOP/MOP last season in monthly doses at a ratio of 1:1 with N. He observed a 10 ppm decrease in K relative to last year. He also observed an increase in P from last year. His CEC is ~13 meq/100g and has a Ca:Mg ratio of ~5. This may have contributed to my conclusion that CEC was to blame.


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## Virginiagal (Apr 24, 2017)

Where did the potassium go? Perhaps it's being fixed. Apparently certain types of soils are more prone than others to taking exchangable potassium and making it go into the fixed pool which isn't picked up by a soil test. Here's one article:
http://www.ipni.net/publication/bettercrops.nsf/0/352CE63CE5BE6D5C8525797C00795F37/$FILE/Better%20Crops%202011-4%20p16.pdf


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## eric1104 (Oct 13, 2020)

Interesting article, thanks for sharing. Although much of the geological terms are beyond my area of knowledge, it seems like a potential explanation for my particular situation. I may try to source a lab that can perform the test. As for what to do if I have a soil that fixes K, I'm not sure.

It's also quite possible I messed up my sampling technique, or sampled at an inappropriate time.

Moving forward though, and perhaps addressing the larger question about what to do with soils that don't hold/or fix K, it seems that regular, foliar applications may be most practical solution?


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## Mightyquinn (Jan 31, 2017)

eric1104 said:


> Mightyquinn said:
> 
> 
> > Well, I have been dealing with this for years as my CEC is 2.2 so you are way better off than I am  I have found that spoon feeding and only giving the lawn what it needs when it needs is the best way. I would recommend trying to find some Potassium Nitrate (14-0-46) and add that to the mix of Nitrogen when you spray as that will help with the grass uptaking the Potassium. With low CEC you can't really pound the soil with anything as it doesn't really hold on to it. I have seen some minor improvements in my numbers over the years but it will take a slow and steady diet approach, like most things in lawn care, it's a marathon and not a sprint.
> ...


I don't remember having any mixing issues with iron other than with Bifen. Iron will mix well with Urea or Potassium Nitrate or both. Last year I applied about 1:1.5 N:K and my potassium numbers didn't really come up that much so I have just become accustomed to feeding the lawn Potassium whenever I can until I see anything otherwise. Just keep after it and keep reading and researching and trying new things. Especially if your lawn looks good, it's even less to worry about.


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## Virginiagal (Apr 24, 2017)

Here's an article I found for someone else on foliar feeding:
https://ipm.missouri.edu/MPG/2019/4/foliarFeeding/

Perhaps you should do a tissue test to see if your grass is lacking in potassium or not. Maybe despite what the soil test says it's getting enough. If you decide to do foliar feeding, maybe get some advice from your local extension agent and if he doesn't know much, get a referral to someone in the university turf department who does know something. Or maybe someone in the agriculture department. If potassium fixation is an issue in your area, farmers are dealing with it too.

The soil test recommendations are recommendations for soil, not for the grass itself. I would expect foliar feeding amounts to be entirely different. You need to consider potential for leaf burn and what proper dilution amounts would be, as well as the amount per 1000 sq ft. With nitrogen, you can judge things by how fast the grass is growing. But how would you judge whether to apply or not apply potassium and how often? You don't want to overdo anything and create imbalances. Lots to research.

Leaving clippings on the lawn is one way to do an ongoing, gentle feeding of nutrients.


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