Heavy clay soil

[Kiril]

Originally Posted by Smallaxe

Another thought occurred to me is: What if th homeowner decided to add 4" of top soil that was High in SOM on top of the clay hardpan... Would that solve his problem?

No it won't.

[Smallaxe]

Originally Posted by Kiril

No it won't.

Again I agree, but it is a common solution in the minds of many an lco... The subject just came up again...

[JFGLN]

Originally Posted by Kiril

If you are willing to till .... then till it, as this is the only reasonable solution, especially if you are dealing with compaction. Soil test and determine how much compost and whatever other amendments you need so you can get it all done in one shot. Proper soil prep is one of the main points to address when establishing turf .... and all too often it is ignored completely or done wrong. For your reference.

http://www.seattle.gov/util/stellent...2021255394.pdf

Thanks for the link. I actually have a copy of that paper. It's good to review it occasionally.

[JFGLN]

Originally Posted by Smallaxe

You said there is a thin layer of topsoil over the clay. How thick is the clay layer?

Tilling in compost is always a good idea, but compost breaks down over time and your soil is back to a platelet structrure.
A sandy compost tilled in thoroughly and deeply, is about the best way to go. If you are able to hit gravel or sand below the clay even better, as it will require less work and material to fix your drainage issue...

Meanwhile mow only when it is dry and allow the soil to dry. Mulch mow and add compost after aeration, which more often the better.

You have a large lawn, only work as much as you can handle with a wheel barrow and regular reartine tiller. Start with the lowest area first and go from there.

If you decide to hotdog it with big bad machines like 'true professionals', your disappoint will continue. Do one spot right and forget about it. A proper lawn with proper soil never needs aerating, unless there is too much traffic, fert, and water...

Not sure how thick the clay is but its defiantly deep. The owner says the landscaper applied 3 to 6 inches of top soil although I dug a couple of test holes and the clay started an inch below the surface.

So my question, Is aeration with a topdress of compost going to help this lawn?

[Kiril]

Originally Posted by JFGLN

Not sure how thick the clay is but its defiantly deep. The owner says the landscaper applied 3 to 6 inches of top soil although I dug a couple of test holes and the clay started an inch below the surface.

So my question, Is aeration with a topdress of compost going to help this lawn?

Is the soil compacted? How deep are you aerating?

If the clay is compacted aeration will not fix the drainage problem. If the clay is not compacted, and you are aerating to a well into the clay, then conditions will improve over time.

You need to map the area for compaction before you can determine what is the appropriate course of action.

.... and buy yourself a soil sampler.

[JFGLN]

Originally Posted by Kiril

Is the soil compacted? How deep are you aerating?

If the clay is compacted aeration will not fix the drainage problem. If the clay is not compacted, and you are aerating to a well into the clay, then conditions will improve over time.

You need to map the area for compaction before you can determine what is the appropriate course of action.

.... and buy yourself a soil sampler.

How do I tell if the clay is compacted? My aerator pulls plugs about 3" deep.

[Smallaxe]

If there is no place to 'punch thru' the clay then you are going to have to live on the hardpan... Like starting a lawn on the sidewalk... 3-6 inches of sandy loam, hope for worms and watch the irrigation...

[Kiril]

Originally Posted by JFGLN

How do I tell if the clay is compacted?

Penetrometer.

Originally Posted by JFGLN

My aerator pulls plugs about 3" deep.

Not gonna cut it.