# Soil Fertility - this is where I start



## etakmit (Oct 31, 2020)

So I mentioned in my intro post that I'm going to start in on my lawn in the spring. Got my soil tested last month just to give me an idea of where to begin.










Thoughts here? In all honesty I cannot say when the lawn had been treated. I had a local service doing treatments this year and prior to taking the sample I can't say when they had done one.

I figure I'll do another test in the spring as well and see what things look like then.


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## Deadlawn (Sep 8, 2020)

It looks like you're in a pretty good place. You may benefit from a topdressing of compost to increase your organic matter and that will also increase your pH slightly.


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## Virginiagal (Apr 24, 2017)

Your organic matter is fine. Adding compost does not increase pH. Your pH is fine anyway.


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## g-man (Jun 15, 2017)

^+1 nitrogen and a maintenance strategy for potassium. 4% of organic matter is pretty good.


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## Deadlawn (Sep 8, 2020)

Virginiagal said:


> Your organic matter is fine. Adding compost does not increase pH. Your pH is fine anyway.


Most compost is slightly alkaline - around 7.5, but point taken it won't significantly increase pH unless your pH is really, really low.



g-man said:


> 4% of organic matter is pretty good.


Hmmm. I thought 4% is at the low end. Isn't optimal between 4 and 20%?


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## g-man (Jun 15, 2017)

I think 20% OM would be a disaster in a lawn, when sampled from 0-4 or 6in depth (very different in the 0-2in depth).

High OM will lead to N mineralization, anaerobic decomposition during high moisture and uncontrolled release of nitrogen when temps go higher. Most golf greens use core aeration and sand topdressing to reduce their OM. I think something up to 5% is a good number.

UM recommends 2-3%
https://extension.missouri.edu/publications/g6955


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## Virginiagal (Apr 24, 2017)

North Dakota recommends 2-4%, advises not to go over 5%:
https://www.ag.ndsu.edu/publications/lawns-gardens-trees/interpreting-the-ndsu-soil-test-analysis-for-managing-turfgrass

Turfgrass roots go through cycles of growth and decay, and the decayed roots are the best source of organic matter in the soil. So grow a vigorous stand of grass to increase organic matter. Also it's easy to mulch mow your leaves and leave grass clippings on the lawn.


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## Deadlawn (Sep 8, 2020)

g-man said:


> I think 20% OM would be a disaster in a lawn, when sampled from 0-4 or 6in depth (very different in the 0-2in depth).
> 
> High OM will lead to N mineralization, anaerobic decomposition during high moisture and uncontrolled release of nitrogen when temps go higher. Most golf greens use core aeration and sand topdressing to reduce their OM. I think something up to 5% is a good number.
> 
> ...


Interesting. High moisture is rarely a problem here with everything below 8 inches being sand. I presume anaerobic decomposition could be a problem with a clay base. In my case, the more water I could get my soil to hold, the better.

I misquoted before. I rechecked where I found a UMass soil test documented in Tukey's Organic Lawn Care Manual which labels *4-10% organic matter* as the "desirable range", not 4-20%. So I stand corrected.


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