New construction home on a field of clay. Where to start with soil improvement ??

Hi everyone. First time poster here. We are building a conventional style home on a half-acre of sloped land that has primarily exposed clay with zero topsoil.  It’s our first exposure to clay - wow!  Hard as a rock when dry and sticky/clumpy on your feet when wet.  I have zero background with soil improvement.

We have $ budgeted to bring in topsoil (4 inches ?).  However I’m concerned it will all end up at the bottom of our slopped lot.  What are your suggestions to do prior to topsoil ?  Instead of topsoil even ?  How to retain the topsoil until grass takes hold ?

Basically, we’d appreciate any suggestions you have on how to proceed.  The end goal is to have a healthy grass covering on most of this land.  We will also have a few garden and flower beds scattered around but they will come later.

Thanks for your help.

Depends on your goals.

Are you into organic or are you going to be using mineral fertilizers and weed killers and the like?

Where are you? Not your specific location, but what sort of climate? Heavy rains? Seasonal droughts?

Hi Thom,
Thanks for your reply.  Not organic except in select raised beds which will come along later.  Not opposed to standard fertilizers and salt/soap based weed killers (prefer smothering initially).

Located in SE michigan.  Short term doughts possible but not that common.  Seasonal heavy rains but nothing crazy.  I'm considering adding irrigation as we're on a well.

regards,
John

Clay can be a bear but it can also be a boon!

For fast establishment, your importing of topsoil will speed things up definitely. You are going to want to mulch heavily while your grass seed establishes. We use straw in my neck of the woods with decent success. I have always spread the seed and watered but I have heard good things about hydro-seeding from those who utilize it. I have never had turf installed, but that is always another option if available in your location.

Clay needs organic matter to loosen it up. I'm a big advocate of lots of compost but it also requires time to work in.

I'm told Gypsum is also a great amendment for clay soils.  (We currently have clay,)  It's a soluble mineral, but it somehow works to make clay act more like loam, I guess?  Allows better drainage for plants to establish and get that microbiota in the soil flourishing.

Otherwise, I would think to suggest planting a few scattered trees or shrubs that do particularly good in clay, mulching well around them to help the soil be healthy, and see if that can't make a good helpful difference to the area around them.  (Mulch, mulch, mulch!)  If those also happen to be nitrogen fixing, that's another bonus.  If you can be successful with clay-happy plants, then I'd think you would have better confidence and practices and environment with/for other plants after that.  

Once upon a time I tried to work compost into my clay... and the tiller wouldn't even grab into it.  So the clay and top mulch never really mixed except with a LOT of work in one spot.  Not really worth it.  Since then I have learned the value of lasagne gardening (putting mulch down as a top layer, like nature does it) that is much easier to do, and still entirely nurtures the soil fauna that makes everything healthy.  I suggest nice thick layers of mulch.  

Welcome to the forum.  It looks like you have a good start with the foundation of the house.

Usually builder add a layer of top soil around new constructed homes.

My suggestion would be to start making compost with whatever you can get you hands on.

Wood chips are also good for trying to better clay.  There are places that will deliver loads for free or a little cost.  Check out Chip Drop:

https://permies.com/t/39157/ChipDrop-site-sign-delivery-free

https://permies.com/t/209527/permaculture/Chipdrop

Hugelkulture beds would be helpful on clay soil:

https://permies.com/f/117/hugelkultur

To improve that clay:

https://permies.com/t/203631/Improving-clay-soil-cheap

I live not far from you, and my lot is hard clay. The builder stripped off the topsoil before building, back in 1980. In 40 years not a smidge of topsoil has formed under the grass. As others mentioned above, the added layer of topsoil, or a lot of mulch is needed.

If you leave it as clay, you will need to water a lot and use fertilizer every year if you want a nice, green lawn.