Question
I have a 25 yr old,MI KY blue sod lawn over extremely compacted soil. I have dethatched once and core airrated 3 times in the past 8 yrs. Soil test aprox 6 yrs ago with MSU Exten said soil in good condition at that time. No amendments have been added other than yrly fertilizer, spring and fall.Grass looks bad with many thin and bare spots. 2 yrs ago I used round up to kill a 300 sq ft area of quack grass, then overseeded with a power unit. Area looks the best of my entire lawn.I want to do something regarding the compacted soil B-4 i kill or overseed the rest of my lawn. Thanks

Answer
Dense, rock hard, compressed soil is not 'in good condition'. Apparently, over a mere 6 years, your soil textured has been altered dramatically.  Heavy equipment rolling over and jabbing into damp soil will do it, even as you aerate and mow.

Tools 'that shear the soil ... have a tendency to cause compaction', note researchers at Kansas State University Extension Service.

'Tillage implements orient soil particles in the same direction.'  The hardpan that follows will be even worse when the land is worked when wet, they say.  You can read the entire essay at the KSU website in their essay, 'Soil Compaction Problems and Solutions':

http://www.oznet.ksu.edu/library/CRPSL2/AF115.pdf

We know that Grass roots grow well in soil with good tilth.  They don't grow at all in Soil with bad tilth.  Without a healthy food chain to generate organic matter and keep the Soil cooking, the Bluegrass monoculture will deplete your Soil of all nutrients.  You however are the one who puts the nail in that coffin when you douse it with annual fertilizer salts and Roundup.

To deal with this problem, the traditional plan of action is to reach for more 'topsoil' and re-sod.  That works for a while.  But if you really, truly want to CORRECT your Soil, you will have to stop using all the heavy equipment, stop the Weedkillers, end your use of concentrated chemical fertilizers, and learn how to grow Grass the 21st Century way.  With the science we have, nothing else makes sense.

You don't want to tear out that beautiful KBG sod, right?  Every authority you contact with this problem is going to tell you that the key is adding organic matter to the compacted Soil -- and AERATE.

I know, I know.  You figure, My Soil has no air spaces; therefore, I will add air.

But there's no way to keep the air from being pressed out unless you alter your Soil structure.  Otherwise, the air will just go UP.

That's where organic matter comes in.  Compost.  Humus.  Aged Manure.  Peat Moss.  Miscellaneous Leaves and Grass Clippings and Vegetable Scraps.  These are things that will solve your problem.  And THEN you can aerate and watch results.

Believe it or not, lots of Earthworms will do WONDERS for your 'extremely compacted soil'.

You probably had Earthworms at one point.  But you need high levels of Organics to build a healthy Phylum Annelida population.  That means making your Lawn Earthworm-friendly.  Imagine being the Earthworm that has to swallow a Turfbuilder-laced mouthful of salty silt.  Earthworms don't like chemicals.  Now, imagine being the Earthworm tunneling through your Lawn as the rain waters your Grubs-B-Gon into the soil; how many will still be around to watch the moon rise tomorrow after that experience?  

Earthworms eat Bacteria and organic matter as they go plowing through the soil.  They boost its value with all kinds of nutrients, and they cast the rest around your yard.  Don't treat them like so much collateral damage.  They are your allies, those Earthworms.  You WANT to keep your Earthworms.

So they like Compost, they love Humus, they love Manure.  But what do they LOVE?

Coffee Grounds!

That's right.  The stuff left over from your morning Java.  The pH is VERY Grass-friendly on USED grounds, and they enrich your soil with plenty of Nitrogen and several other very good things.  But the BEST thing about used Coffee Grounds is that Earthworms LOVE them.

Starbucks gave away USED Coffee grounds last year.  You can take their used Grounds home and put it in your yard, your Garden, anywhere you want to raise the soil's value.  And because these Coffee Grounds are FREE, it won't cost you a dime.

You also want to top dress your soil with one or all of the Organic amendments listed above.  If you have Earthworms down there, they will come up at night hunting for the Organic Matter.  Earthworms have to eat, too, and your depleted Soil is a little bland these days, so they'll come upstairs hunting for that Organic matter, tilling the soil underground as they move up and down.

You don't think they can handle a job that big?  Earthworm castings are INCREDIBLY good for your Soil.  50 percent HIGHER in Organic matter.  7 times RICHER in Phosphorous.  PACKED with 10 times more Potash than plain, ordinary, Earthworm-free soil.  5 times higher in Nitrogen, 3 times in Magnesium, and 1 1/2 times higher in Calcium.

Charles Darwin watched Earthworms work at night poking through the Soil, pulling dried leaves and stems down into the ground.  Then he wrote a book about them, 'Formation of Vegetable Mould Through the Action of Worms'.  There are MILLIONS of Earthworms in an Acre of healthy Soil.  Researchers in one study calculated that for your typical acre, 16,000 lbs of soil pass through Earthworms and are deposited on the soil surface.  

Without the help of those Earthworms, simple aeration won't be worth a hill of beans, as they say.  University of Illinois Extension Service posts their advice on compacted soil at its website:

http://www.urbanext.uiuc.edu/soil/sq_info/RSQIS4.pdf

They report: 'What breaks up a compacted layer?  Natural recovery is often slow, taking years to decades or more.  Cycles of wetting and drying and of shrinking and swelling can break down compacted layers ... Roots help to break up compacted layers by forcing their way between soil particles.. (and) by providing food that increases the activity of soil organisms' -- Earthworms, Ants and Termites.

You probably like to remove those Grass clippings, rake up the Autumn leaves and those Thatch pieces, keep your Lawn neat and tidy.  

As the KSU authorities point out, 'Practices that leave soil residue undisturbed help increase or maintain a good organic matter level, which favors good Soil structure and reduces the potential for compaction.'

Purdue University Cooperative Extension Service maintains that 'farmers shouldn't underestimate the soil loosening power of nature':

http://news.uns.purdue.edu/UNS/html3month/021004.Vyn.subsoiling.html

Purdue insists that 'compaction can be alleviated by natural processes like soil wetting and drying, earthworms and crop rooting activity. Compaction can be alleviated even further by frost activity over the winter.'  Luckily, you  live in Michigan.  

Now, I know this all must sound a little extreme.  You have fertilized faithfully -- odds are that bag of fertilizer has the name Scotts all over it.  The Scotts Company seems to be the source of almost everything people know about Lawn care today.  But think about it.  Going to Scotts for an education about Grass is like reading Pravda under Stalin for current events.  

There's a guy in Illinois named Robert F Gabella who has a website, GardenOpus:

http://www.gardenopus.com/Fertilizing%20New%20Sod.htm

Rob Gabella addresses this very problem.  He writes: 'If you asked a nursery professional, they would often sell you a 5-bag program for the entire season - that's their job (but not mine!), that's what the factory rep trains them to do, and that's what their boss needs them to do to move the inventory.  Save the money on the extra bags, pay a little more for the amount of organic product you actually need, and your lawn should do fine!'

If Robert Gabella and our top agricultural research labs advertised on Superbowl Sunday, George, people would learn about Lawn Care from THEM.

Instead, we have a megamulti-national company that essentially OWNS the Fertilizer-Lawn Care Business, educating the world.  And people respond with their Lawn Care Dollars by the BILLIONS.

Nothing wrong with Scotts advertising.  But the message is too loud and WAY too effective.  There was a time when those products were cutting edge, but that was DECADES ago.  Update and upgrade, George.  You know that Science marches on.  Get another Soil test.  Find out what your pH is.  Go into 'CORRECTION' mode and work overtime to build up your Soil with microorganisms and arthropods and gastropods.  Look around -- See any Birds?  Feed them!  Invite them over for breakfast.  Put out a Birdbath.  This is the Space Age.  The Earth is Round.

Boy, look at the time!  I'm hungry.  Thanks for writing.