# Super compacted soil



## spaceman_spiff (Feb 5, 2021)

I've got a strip in my back yard that, for whatever reason, would grow grass, but it would die off and even get pulled up easily once summer rolled around. This stripe through the back yard gets the most sun, so I figured it was an irrigation issue. I spent an endless amount of time messing with the irrigation nozzles trying to get more water down on the spots. Nothing seemed to work.

Yesterday I started digging where there is bare dirt and I found that there's 2 inches or so of loose topsoil, and then it hits a section of super compacted soil. Even if I use my Yard Butler manual core aerator, it can't penetrate this layer of soil. It just clogs up the tines and is a super PITA to clean out every 15 secs.

I figure if I have a company come in and aerate 200 ft.² they'll probably laugh at me but also I'm not sure if the tines on a aerator machine would be able to penetrate the soil anyway.

Any ideas? Should I dig out the top 2 inches of loose topsoil and then spray the lower layer until it's soaked and try to manually aerate again?


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## knotweed_king (5 mo ago)

It could be compacted from when the house and sidewalk was built. And if they when they mixed the concrete maybe some fine particles mixed with the existing earth, essentially forming concrete which can happen when you mix soils. I've also heard of these soil layers when new material is added on top of existing compacted soil, and what happens is the water penetrates the topsoil, hits the compacted soil underneath and then just runs off.

2" of topsoil isn't much. You could get a tiller that goes 10-12" deep rented from a big box store. There may be models that go even deeper. Till it up and work in a lot of organic matter (compost) at the same time. You may also consider a soil composition test on the compacted sub-soil.


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## spaceman_spiff (Feb 5, 2021)

Hmm, tilling it up would probably be a good idea. Only problem is I don't know where my irrigation laterals are. That could be messy :lol:


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## moedank (Sep 10, 2019)

If you don't want to till use an auger bit like the one linked below to drill 50-100 holes in that area. Then, plug them with a mixture of compost and loose soil from the holes.

https://www.menards.com/main/tools/...drill-bit/xab0116/p-1444448113895-c-10079.htm

Luckily, you won't look insane to your neighbors since you'll be hidden by the privacy fence. I had a neighbor blankly stare at me from across the street while I was drilling holes in the side lawn a couple weeks ago. I've accepted that my neighbors think I'm bat shit crazy.


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## knotweed_king (5 mo ago)

spaceman_spiff said:


> Hmm, tilling it up would probably be a good idea. Only problem is I don't know where my irrigation laterals are. That could be messy :lol:


Ah yes, I forget that people have in ground irrigation. Yea that could definitely be problematic and expensive. Manually drilling holes and backfilling with compost seems feasible for the small area. A potentially crazy option would be to grow diakon radish which can grow up to 2' deep and will drill through that compacted soil, then just leave them in there to decompose and aerate your soil. I've seen people do this for clay soil remediation.


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## spaceman_spiff (Feb 5, 2021)

moedank said:


> If you don't want to till use an auger bit like the one linked below to drill 50-100 holes in that area. Then, plug them with a mixture of compost and loose soil from the holes.
> 
> https://www.menards.com/main/tools/...drill-bit/xab0116/p-1444448113895-c-10079.htm
> 
> Luckily, you won't look insane to your neighbors since you'll be hidden by the privacy fence. I had a neighbor blankly stare at me from across the street while I was drilling holes in the side lawn a couple weeks ago. I've accepted that my neighbors think I'm bat s--- crazy.


This is probably my best course of action. I just got a yard of 3/8" top soil and compost delivered yesterday. Looks like a trip to Home Depot is in my plans for tomorrow. Thanks!


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## spaceman_spiff (Feb 5, 2021)

And I have been doing a front yard reno for the past month. Seeded on Monday and have been strategically re-filling in areas with handfuls of peat moss as it washes out. Pretty sure my neighbors already think I'm crazy. I'm the guy that's had a dirt front yard for a month, ha.


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## spaceman_spiff (Feb 5, 2021)

@moedank

Ok I already don't like you. 50 holes in like 5 sqft and I'm already exhausted :lol:


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## moedank (Sep 10, 2019)

@spaceman_spiff, that's going to eventually be the best 5sqft of the entire lawn.  I reserve the auger bit for the worst compacted clay areas. It's nice since you can drill down a lot deeper than a typical core aerator. Just time consuming. This should really help with compaction by incorporating organic matter deeply into the ground.


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## spaceman_spiff (Feb 5, 2021)

moedank said:


> @spaceman_spiff, that's going to eventually be the best 5sqft of the entire lawn.  I reserve the auger bit for the worst compacted clay areas. It's nice since you can drill down a lot deeper than a typical core aerator. Just time consuming. This should really help with compaction by incorporating organic matter deeply into the ground.


Oof, I'm like 1/3 of the way done, gone through 7 batteries, and have already dulled my $40 auger. Wow.


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## moedank (Sep 10, 2019)

@spaceman_spiff, I didn't know how long mine would last and knew its only use would be drilling dirt so I bought the cheapest one I could find, which happened to be at Menards. I can't tell if it's dull or not now but it still drills holes just fine.

How deep are you drilling? 7 batteries for 50 holes? This definitely can stress a drill so I give it a slight rest every 5-8 holes. I haven't drilled as tightly as you but I don't remember having to go through many batteries with a 4.0Ah battery. Use a 24v brushless Kobalt.


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## spaceman_spiff (Feb 5, 2021)

@moedank Been at it for most of the day now. Had to go out and buy a second auger and it's almost toast too. This is some hard clay, damn. I'm going 6-8" deep, whatever the ground let's me do at that particular point.

I have to switch between 2 drills since they overheat after 20-30 holes. My hands are sore as hell, haha.


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## spaceman_spiff (Feb 5, 2021)

Just discovered a drain I never knew I had, ha!


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## knotweed_king (5 mo ago)

Looks good. Maybe a corded hammer drill would have helped you. Comes with a side handle to reduce fatigue. Or a joist drill. I always try to find excuses to buy tools I may only use once but then I have it just in case I can find another use for it.

Your soil will definitely be improved after this and back filling with compost.


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## spaceman_spiff (Feb 5, 2021)

There goes all my hard work



Have a small section I'll knock out tomorrow and seed.


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## moedank (Sep 10, 2019)

@spaceman_spiff, that pic with the drilled holes is beautiful. Brought a tear to my eye.

I'm certain that area will do well. Looking forward to seeing how well it progresses.


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## MacLawn (Oct 26, 2021)

moedank said:


> If you don't want to till use an auger bit like the one linked below to drill 50-100 holes in that area. Then, plug them with a mixture of compost and loose soil from the holes.
> 
> https://www.menards.com/main/tools/...drill-bit/xab0116/p-1444448113895-c-10079.htm
> 
> Luckily, you won't look insane to your neighbors since you'll be hidden by the privacy fence. I had a neighbor blankly stare at me from across the street while I was drilling holes in the side lawn a couple weeks ago. I've accepted that my neighbors think I'm bat s--- crazy.


My neighbors think Im nuts for sure.
Even think im nuts cause I fly a flag on a pole and my house?


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## MacLawn (Oct 26, 2021)

spaceman_spiff said:


> I've got a strip in my back yard that, for whatever reason, would grow grass, but it would die off and even get pulled up easily once summer rolled around. This stripe through the back yard gets the most sun, so I figured it was an irrigation issue. I spent an endless amount of time messing with the irrigation nozzles trying to get more water down on the spots. Nothing seemed to work.
> 
> Yesterday I started digging where there is bare dirt and I found that there's 2 inches or so of loose topsoil, and then it hits a section of super compacted soil. Even if I use my Yard Butler manual core aerator, it can't penetrate this layer of soil. It just clogs up the tines and is a super PITA to clean out every 15 secs.
> 
> ...


Figure out where those irrigation lines are! It also looks like that area is used for a path more than the cement pad and the small stepping stones.

As far as small areas. A company serious about servicing customers wont laugh at your needs. Just dont shocked by the price for a small job.

Maybe get the entire lawn aerated with special attention to that area.


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## spaceman_spiff (Feb 5, 2021)

knotweed_king said:


> Looks good. Maybe a corded hammer drill would have helped you. Comes with a side handle to reduce fatigue. Or a joist drill. I always try to find excuses to buy tools I may only use once but then I have it just in case I can find another use for it.
> 
> Your soil will definitely be improved after this and back filling with compost.


I've bought so many Ryobi tools in the past 3 months from crazy sales that I've had to start hiding them from my wife :lol:


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## spaceman_spiff (Feb 5, 2021)

MacLawn said:


> spaceman_spiff said:
> 
> 
> > I've got a strip in my back yard that, for whatever reason, would grow grass, but it would die off and even get pulled up easily once summer rolled around. This stripe through the back yard gets the most sun, so I figured it was an irrigation issue. I spent an endless amount of time messing with the irrigation nozzles trying to get more water down on the spots. Nothing seemed to work.
> ...


It's definitely a huge slab of hard clay after spending all day drilling holes in it. It doesn't get any more foot traffic than the other parts of the yard.

I drilled a few holes in other places and it went right in with no resistance, so I'm 98% sure the compacted clay is what is preventing me from keeping grass alive along that strip.


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## Erinweed (5 mo ago)

So much respect for all the drilling. I tried that once 2 years ago, but burned up my hammer drill. I literally made pottery with my clay. I never filled my holes, and they were still there this fall when I finally dug into it this fall. I think you're going to have good results with all that work


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## g-man (Jun 15, 2017)

I fear that this was not necessary. I think some proper water cycles would help. Did you back fill with sand?


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## Allan-00 (Aug 6, 2019)

knotweed_king said:


> I always try to find excuses to buy tools I may only use once but then I have it just in case I can find another use for it.


This +1


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## mamoore9 (9 mo ago)

g-man said:


> I fear that this was not necessary. I think some proper water cycles would help. Did you back fill with sand?


Can you expand on what you mean by proper water cycles?


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## spaceman_spiff (Feb 5, 2021)

g-man said:


> I fear that this was not necessary. I think some proper water cycles would help. Did you back fill with sand?


My Rachio always does water/soak cycles. I've tried mucking with the duration, crop coefficients, soak cycles, everything to no avail. I'll water it for an hour, dig down and find that the clay layer is barely wet at all due to the super compaction. I'm placing my money on it being too hard for grass roots to penetrate, so hopefully this aeration will help give the roots places to grow down.

I've been backfilling it with a 70/30 mix of 3/8" top soil and compost.


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## moedank (Sep 10, 2019)

I've drilled several times with great success, usually 1x1 to 3x3 sqft areas. I was certain one spot on the side lawn had construction debris underneath so decided to dig it up. Inch after inch, the shovel kept sounding like it was hitting concrete - it wasn't. It just happened to be very compacted clay. I dug down to about 16 inches and stopped. No rocks or concrete. Filled the hole with a mixture of bagged topsoil and compost and drilled the surrounding section. Grass grew in excellently well.

Is drilling holes necessary? Probably not but that can be said for 3/4 of the advice suggested on this lawn enthusiast forum. We intentionally do the unnecessary things.


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## g-man (Jun 15, 2017)

Infiltration rates of water can be low at 0.1in/hr. I would have done a test of using a hose and watering this area every hour or so for a day. No rachio or anything like that. To me it was just dry soil. No harm in doing the drilling, but time consuming. I would have filled the holes with sand.


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## spaceman_spiff (Feb 5, 2021)

g-man said:


> Infiltration rates of water can be low at 0.1in/hr. I would have done a test of using a hose and watering this area every hour or so for a day. No rachio or anything like that. To me it was just dry soil. No harm in doing the drilling, but time consuming. I would have filled the holes with sand.


Yeah probably would have been a good idea to try.

I only used the top soil/compost mixture since I already had a pile of it delivered for around our pool.

And yes, very time consuming. Spent my whole morning doing the rest of my dead strip. At least it's finally done. We're getting 1" of rain early next week, so I'll probably wait until afterward to seed to risk washout.


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## MacLawn (Oct 26, 2021)

spaceman_spiff said:


> MacLawn said:
> 
> 
> > spaceman_spiff said:
> ...


Between the drain and what I assume compacted base a few feet beyond the concrete slab to support the edge maybe. Sounds like that base clay was getting nice and wet over the years then the heat and any draught made one big brick under there.
Good luck , maybe a heavy dose of some wetting agents , or artificial turf if this does not work out.


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## spaceman_spiff (Feb 5, 2021)

MacLawn said:


> Between the drain and what I assume compacted base a few feet beyond the concrete slab to support the edge maybe. Sounds like that base clay was getting nice and wet over the years then the heat and any draught made one big brick under there.
> Good luck , maybe a heavy dose of some wetting agents , or artificial turf if this does not work out.


I know this is heresy on these forums, but I'd love to do artificial turf back there and around my pool, but we have a gigantic 45-foot oak that just craps acorns, leaves, and pollen-y junk 10 months of the year. It would be an absolute nightmare to keep it cleaned off and nice. I'm currently paying my kid $40 for every 5-gallon bucket of acorns he picks up from the grass for the past month :lol:

It's definitely possible that over the years it has just dried up. I moved in 2.5 years ago, and it seems to be a theme that the previous owners didn't give a crap about or maintain anything. It's entirely possible that they under-watered enough that it would completely dry out.

I do have some SLS liquid aerator that I got for dirt cheap, so maybe after the new grass is established, I'll give that a shot between deep soakings.


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## Marzbar (Aug 2, 2020)

g-man said:


> Infiltration rates of water can be low at 0.1in/hr. I would have done a test of using a hose and watering this area every hour or so for a day. No rachio or anything like that. To me it was just dry soil. No harm in doing the drilling, but time consuming. I would have filled the holes with sand.


What is the benefit of filling the holes with sand versus organic matter? I'm still learning.


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## g-man (Jun 15, 2017)

Organic matter will decompose and it will end up with no structure. The clay around it will take up the space.

A sand channel from the top (no topsoil on top), will provide a path for water to take. There is a YouTube video that shows the effect of sand on clay.


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## knotweed_king (5 mo ago)

Could you share the youtube video? I've read and seen a lot where adding sand to clay results in concrete. I guess these sand columns may be different but over time won't the soil will move around, how long will those sand columns remain in tact?

https://extension.illinois.edu/blogs/good-growing/2018-01-31-does-sand-improve-clay-soil-drainage


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## g-man (Jun 15, 2017)

Multiple Youtube videos on this subject. This one is more specific to the sand channels.

https://youtu.be/ego2FkuQwxc?t=699


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## spaceman_spiff (Feb 5, 2021)

Well... now I immediately regret backfilling with not-sand :lol:

Thanks for the video.


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## Pandaluv (4 mo ago)

Personally, I would have just used a mattock. It's tiring yes, but I've done areas around that size in about 30min. It does as good of a job as a cultivator. Nevertheless, great job! It's going to be such a healthy area in your yard now.


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## knotweed_king (5 mo ago)

Interesting video, thanks for sharing. I suppose sand channels in clay are different than top dressing with sand. I have clay filled with rocks as my native soil. I may do a test in a small area were I install these sand channels connect to the surface.. time to get the hammer drill out.


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## Marzbar (Aug 2, 2020)

I think I have the same problem. Here are 2 areas of my front yard tested with a 6" screw driver.



Should I start drilling holes and filling them with sand? Is there anything else I can do?


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## Marzbar (Aug 2, 2020)

@spaceman_spiff any progress pics on your project area?


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## spaceman_spiff (Feb 5, 2021)

@Marzbar 
I seeded a week ago. No germination yet. Existing grass is growing like crazy though.


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## spaceman_spiff (Feb 5, 2021)

Still no germination after 10 days. I think I'm going to rough up the soil and throw down my Super Turf II seed, and consider my 1yo bag of SSS mix dead.

Side question regarding the compaction. I just read about gypsum. It's supposed to help loosen compacted soil / hardpan. Does this stuff actually work, and is it worth a shot?








Hi - Yield Fast Acting Gypsum


Hi - Yield Fast Acting Gypsum




www.domyown.com


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## spaceman_spiff (Feb 5, 2021)

Yep, day 11 after seed down and no sprouts at all. I’m considering this old seed toast. Will reseed today with my new Super Turf II and follow up here in a week or two.


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## Factor (Oct 10, 2019)

spaceman_spiff said:


> consider my 1yo bag of SSS mix dead


As time goes on the germination rate drops. This also affected by where the seed is stored and the environment. I try to get seed as close to seed time as I can like early Summer. I also have seen seed take 14 days or more. Yes if you have 0 germination you will need to have some kind of new plan.



spaceman_spiff said:


> compacted soil / hardpan


Sand and aeration will help drainage and loosen soil.

This will help with Gypsum Will Gypsum Improve Clay Soil? - Garden Myths


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## spaceman_spiff (Feb 5, 2021)

@Factor 
Thanks for the gypsum link! Good stuff. Doesn’t sound like it will really do anything since I don’t have sodic soil. Actually the opposite. Sodium was way low on my soil test.


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## Factor (Oct 10, 2019)

spaceman_spiff said:


> @Factor
> Good stuff.


Robert is really good. Check out his Youtube channel as well. It more on Gardens but Fertilizer and soil all translates over well.


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## spaceman_spiff (Feb 5, 2021)

16 DAG
Looking green!
From the top down, it looks a bit thin, but I’m sure it’ll thicken up with some time and nitro. Also need to get my kid back on acorn duty…

















From the side it looks great though! Hopefully it can stay that way through next summer. That’s the real test.


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