# Soil Test Results - February 2021 - Recommendations?



## Tide (Aug 6, 2019)

How would you all recommend I address my current soil conditions?

My soil test is showing excessive phosphorus. Are there any concerns with this current level?

Also, I was planning on using muriate of potash to increase potassium as that appears to be the most important thing to correct based on these results. I understand muriate of potash is harsher on the soil than sulfate of potash, but would it be enough of a difference to be significant in any way? Any suggestions would be greatly appreciated! Thanks so much!


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## Phids (Sep 24, 2020)

Yes, that level of P is something to be concerned about because it very well may be at toxic levels. In my opinion, it is probably the worst nutrient for overapplication on a lawn. Research shows that overapplication can decrease beneficial mycorrihizae and/or plant growth-promoting bacteria. High P can also lead to problems with uptake in Fe and Mn.

If you had soil that was more acidic, a somewhat elevated P level might have been justified, but your pH level is not in the acidic range.

Perhaps the worst thing is that P toxicity does not correct itself quickly. I would recommend avoiding all applications of P for the rest of the year and retest next year.


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## Tide (Aug 6, 2019)

Phids said:


> Yes, that level of P is something to be concerned about because it very well may be at toxic levels. In my opinion, it is probably the worst nutrient for overapplication on a lawn. Research shows that overapplication can decrease beneficial mycorrihizae and/or plant growth-promoting bacteria. High P can also lead to problems with uptake in Fe and Mn.
> 
> If you had soil that was more acidic, a somewhat elevated P level might have been justified, but your pH level is not in the acidic range.
> 
> Perhaps the worst thing is that P toxicity does not correct itself quickly. I would recommend avoiding all applications of P for the rest of the year and retest next year.


Thanks so much for the detailed advice you provided! This is what I was afraid of. Interestingly, my pH was at approximately 5.1 in June of 2020 and my phosphorus level was at 109 ppm. During the fall, I applied lime to regulate the pH, but I didn't apply much phosphorus. The only phosphorus added after that test was from 16-1-2 GreenTRX fertilizer. I'm assuming the best way to lower phosphorus is to remove all clippings from the lawn in addition to your recommendation of not adding any additional phosphorus to the soil.

What are your thoughts? Any other recommendations for other aspects of these test results?


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## Phids (Sep 24, 2020)

Tide said:


> What are your thoughts? Any other recommendations for other aspects of these test results?


In case of nutrient toxicity, two basic options are to have the grass suck up the nutrients (and yes, get rid of the clippings), or to apply woody mulch on top, which can slowly extract some nutrients (these are based on research from horticulturalist Dr. Linda Chalker-Scott). Obviously, the second option isn't good for a growing lawn, so you have to wait it out and use option #1.


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## stevehollx (Apr 8, 2020)

Do you have a dog? My back yard is high in phosphorous and my front yard is low. Pretty sure the dog waste is the reason for me, as I don't use balanced fertilizer anywhere and my dog is the anomaly of front-to-back. Maybe switch to full urea for fertilizing, and of course avoid milorganite or other organic additives.

Spraying chelated zinc may help reduce phosphorous but at a glance research material mostly is around how phosphorous reduces zinc levels so not sure the activity works in the other direction.

You can plant tomatoes in your yard--they take up phosophorous. And then you get fresh tomatoes! But then you won't have a lawn.


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## Tide (Aug 6, 2019)

stevehollx said:


> Do you have a dog? My back yard is high in phosphorous and my front yard is low. Pretty sure the dog waste is the reason for me, as I don't use balanced fertilizer anywhere and my dog is the anomaly of front-to-back. Maybe switch to full urea for fertilizing, and of course avoid milorganite or other organic additives.
> 
> Spraying chelated zinc may help reduce phosphorous but at a glance research material mostly is around how phosphorous reduces zinc levels so not sure the activity works in the other direction.
> 
> You can plant tomatoes in your yard--they take up phosophorous. And then you get fresh tomatoes! But then you won't have a lawn.


Haha! We don't have a dog. But, there are quite a large number of wild cottontail rabbits around our home. We leave them alone because they're fun to watch and do provide at least some organic fertilizer material back to the soil.

Since my zinc level is already high, I'm hesitant to add any more to the lawn than is necessary. I'm guessing there might have been a sampling error or something else that created the discrepancy between tests (pertaining to phosphorus, specifically). Either way, the phosphorus level is big concern for me in addition to the low potassium level. I think I'm going to apply muriate of potash and remove my lawn clippings to try and balance out these two nutrients a little more.


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## Tide (Aug 6, 2019)

Does anyone have any thoughts on potentially adding silica to the equation? I've read that silica can lessen the negative effect that high phosphorus levels have on iron availability in addition to generally being good for the strength of the grass. @Greendoc and @Ridgerunner , is this a good idea, or should I just skip the silica?


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## Greendoc (Mar 24, 2018)

Your P is not that high. Do not add any. Potassium is low though. I would be thinking about applying equal amounts of Potassium for every unit of N applied.


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## Ridgerunner (May 16, 2017)

Doc's got it covered.


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## Tide (Aug 6, 2019)

Excellent advice! Thanks, y'all!


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