I got my lawn core aerated the other day. Some parts of the lawn have core plugs that are a nice rich dark color (at least I think this is nice/good). Other sections of my lawn have core plugs that are much lighter. Is that indicative of not having enough organic matter in these parts and the soil has more clay in it? It just so happens that these parts where the lighter core plugs are happen to be the more problematic parts of the lawn (more weeds, more dead spots).

  • Hi! Can you please post some pictures of your lawn? A look at the whole thing, and some closer views of the places where the colors are different would be great! Thanks! Commented Oct 4, 2017 at 18:02

2 Answers 2


So, the color of soil comes from what is in it or what is NOT in it (as you indicated in your question), its drainage, as well as lawn or land physical Geo (hill slopes, flat, rocky mountainous, etc, and the age of it's contents. Lighter colored soils tend to have less active organic material and more sand or rock. Soil light or very light in color means it has between 1.5-2% organic matter, where your dark or very dark core samples are between 3.5-5% organic matter.

I am including the link where I obtained this information. This site is FULL of soil info and how to understand your core samples. Let me know if you cannot open the link. Also check out pic below link!


Screen shot of PDF from above link, showing color chart soil descriptions

  • I think there is more to this question than soil. It is rather cool this guy actually LOOKED at these cores. I think a major gardener in the making. There is no such thing as BAD soil, unless toxic residue. None. Adding decomposed organic matter (just to the surface of prepared beds) is the absolute best and only way to improve soil. No other additions. Raised beds. Not meaning beds with wooden or concrete sides... Lawns...this must have been his first aeration. The different colors show the history.
    – stormy
    Commented Oct 7, 2017 at 0:37

Dark soil versus light soil means lots of different things. First would be moisture content. Second organic material content. Third possibly a layer of non indigenous soil that was installed earlier. Those are the top three I can think of...

You've probably got dry areas of grass where the grass is weakened and of course weeds will move in...I just have to point out that dark, friable, organic 'rich' soil is NOT FERTILE soil. Just great tilth. Soil is NEVER fertile meaning the soil has all the nutrients plants need to photosynthesize to make their own food and thrive. Potting soil is dark and friable. But in no way is potting soil 'Fertile'...People think that the soil on an old forest floor is fertile. No way is that true! In fact, the older and more successful a plant ecosystem is the less one will be able to find the chemistry, nutrients plants need to have! The chemistry is tied up in the biomass of the system.

That forest floor soil most certainly has lots of decomposed organic matter in it...nice and dark. But not fertile.

When rain forests are cut down that soil might produce a meager crop but forget the next year! 'Nutrients' or I prefer chemistry, are only released to the soil after decomposition of dead plant material thus allowing for necessary chemistry for the entire system or maybe a newbie plant can be allowed to find a niche.

I now have pumice for soil for my greenhouse soil. I've had yummy loam soils ijn the past. Mostly I've had clay (to include caliche clay) and if you know how to manage a clay soil it is wonderful soil'

The only way to improve any soil (texture) is by the addition of DECOMPOSED organic matter. Sorry I had to capitalize that word because it is essential to know the difference. Grins. I miss my clay soils!

Do you have an automatic irrigation system? Is this the first time you've core aerated? Have you ever top dressed? What do you use for fertilizer? What type of grass, no where is it that you live? Your observation can tell you an awful lot and I'd hate to let you think it is because you've got 'fertile' soils and 'infertile' soils. Just not true nor meaningful.

  • I never even thought of the idea of it being caused by transplanted soil from elsewhere. Good thinking @stormy !
    – Christy B.
    Commented Oct 5, 2017 at 4:39
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    That is what is wonderful about team work. Put a few minds on a problem and fascinating answers arrive...that are better than an answer from just one mind. I know soils very very well. Dunno why I was so in love with soil because soil is just soil...little rocks of different sizes. My favorite is clay. Soil is alive and real and gets under the finger nails and grooves of wrinkles!! ha ha ha!
    – stormy
    Commented Oct 6, 2017 at 0:42
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    You can get over clay as a bad guy. I'll help you. I miss clay soil! Do a mason jar test with a cup of soil and water. A quart mason jar. Shake it up and allow it to settle. A day or two...I still have one from 5 years ago that I use to check the progress of my soil's tilth. Pure pumice almost zip organic matter. Double dug and added decomposed organic matter by throwing it in as I dug. Down about 12 to 18 inches, just turning the soil over. The bed gets up to 3 feet high. I rake it down, use plywood to compact...jump up and down, look dumb. Make a trench all around the border of...
    – stormy
    Commented Oct 7, 2017 at 1:43
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    ...the bottom of my 3 to 4 foot wide beds for drainage, throw that soil on top of the beds, rake, compact. I plant my starts or seeds. I coat the top of the beds at least 2 inches with this decomposed organic matter...I wait for the seeds to get 4 or 6 inches high before using this stuff on those beds.
    – stormy
    Commented Oct 7, 2017 at 1:46
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    You can stop worrying about clay and look forward to allowing your gram to sit and enjoy her last gardens. Well, hopefully she'll get out and move and work a bit in the garden...keep her living longer. Good grand daughter! Grins!!
    – stormy
    Commented Oct 7, 2017 at 1:54

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