Add 3-4" of compost on top of the entire area that you're amending, and then till it in well. The organic matter will help to improve drainage and lighten up the clay. You have to be careful when adding sand to clay, as you could make matters worse. Gypsum is another option for loosening clay.

thanks, i will skip the sand

You're welcome! Mulch, mulch and mulch some more once you're done with amending. The decomposition of the organic matter will help to further improve the soil. Grab yourself a copy of "Teaming with Microbes" while you're at it. It's a wonderful introduction to the soil food web, and will guide you in the right direction in terms of materials to use for mulch, based on the types of plants that you're attempting to grow. Teaming with Microbes

I am really interested in growing an alternative lawn in addition to a garden. will see how that works out. right now, the clay is quite thick in spots and will not drain at all. I try to save as many leaves as i can and turn them into mulch. in spots I just let it sit and decompose over time. Thanks for the recommendation. I will try to read up on it.

The only thing wrong with most clay soils is a lack of adequate amounts of organic matter. Forget about that something called "topsoil" and just add compost, but understand that you will not see great results for a few years, improvement will not happen overnight.

Gypsum will only help some soils mostly in the southwest areas of the United States, not all clay soils.

What are you going to do with all that sod? I hope you are either going to incorporate it into the existing soil, or compost it. That's where any 'topsoil-like' qualities will exist.

If you have access to wood you could bury some, will help the soil over long term. Look up hegelkultur (not sure about spelling).

Yikes. I have different advice than others.

If you have drainage problems, I doubt that ‘tilling compost into the clay’ will make any difference. You’ll need to redirect the surface runoff away from problem areas.

Tilling organic matter into soil is bad advice. OM needs to stay on the surface of soil. If you want quicker results with tilth, apply humic shale ore (pelletized).

Fix the drainage. Plant in the native topsoil. Put OM on the surface of the soil.

I have no opinion on tilling, but don't think surface runoff necessarily has to be redirected. It doesnt sound like a major drainage problem, but seasonal/heavy rain, which could just mean the soil there has different clay mix or is heavily compacted in that area or that part of yard just lower and tends to collect there. Some types of clay-heavy soil just drain more slowly (and I think fair to say don't absorb/release - buffer - water the way more organic soils do). Amending with OM and use of deep-rooted plants/cover crops may be enough. Hugelkultur (burying wood) is another technique said to improve drainage.

An article that overlaps with much of what has been suggested here:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/yard-drainage-problems.htm

Obviously could be a major drainage problem or related issue like a very high water table, but easiest to start with more simple solutions.

thanks everyone for your comments and suggestions. I don't really have any real sod but a bunch of weeds growing right now. I am not going to compost that one on my property. I am bringing in topsoil/compost mix in order to fill in major dips in the yard. the dips themselves are right around the house walls and all the rain water is pooling there to the point I have a little tiny pond there when spring rains come. My reasoning for tilling in the soil into the existing one throughout the yard and then moving it properly around was consistency. I have a feeling that if I only dump the well training soil into a hole surrounded by lesser draining soil, water will still pool in the same spot and not run off properly down the slope. If I mix it all together and then distribute it I think it would be better. Am I wrong? Also, since there was not much growing other than weeds I thought more nutrient soil would benefit a ground cover of some sort, I am planning to mix micro clover, some grass, English daisies, chamomile, and some other plants to create some lawn like area surrounded by native blooming plants. I am in Michigan. I collect and save leaves, of which I have an abundance. I usually turn it into shredded leaves and mulch the beds I already created. We cut down many trees as they were endangering the foundation of the house and there are many roots left. I guess they can work as a Hugel Kultur over time .

Festiva, the difference in soil is amazing. Yes, I am trying to do the same thing. How do you shred your leaves, or do you just leave them the way they are? I used to run my leaf pile over with the lawn mower each fall but was not able to do it last year. Last time I did it, the soil was so much better after just one season.

I am not concerned to grow a pristine lawn as I don't like them. We have already a lot of violets and indian strawberries which take over the yard. There seems to be just a small patch of 1x2 feet of grass in the whole yard. The previous owners left the self seeded trees grow so dense, they created a dense canopy where no light came through and the roots destroyed the foundation of the garage. Some grew so close, they were touching the walls of the house.

I'm so thankful for all the autumn leaves! Every fall I roam the neighborhood with a wheelbarrow and scoop up piles from the curb before the county comes by with their vacuum truck. If they are nice and dry, I spread them all over the lawn and run the mower up and down until they almost disappear. I also shred some with the mower and spread over the vegetable and perennial beds. (In the beginning I used to dig them in but now my garden is mostly no-dig.) I also save lots of them in a leaf mold cage. These wait until next spring to be mixed with fresh grass clippings and make leaf compost for mulching later in the season. I always want to save some to make leaf mold, but somehow I always run out...

Your lawn description reminds me of my own: lots of clover, violets, dandelions, etc. but I keep it trimmed and it serves its purpose just fine :)

Paul, I’m not sure what led you to the misconception that tilling compost into clay would not improve soil texture and drainage. Have you ever tried? How would “fixing drainage” improve the heavy clay beneath the surface? Adding compost would loosen the clay and improve drainage - it’s common knowledge. OM very much belongs in the soil - have you noticed that soil tests will yield results for organic matter % and provide suggestions for increasing it? Please educate yourself on the topic before providing misinformation.

High organic content mixes used to fill low spots will result in a return to them being low spots after the organic component has decomposed completely and vanished. Likewise significant amounts of organic material incorporated into soils intended to become a substrate for lawns can also result in sunken areas later.

The Myth of Soil Amendments, Part III
“Healthy soil has high organic content”

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/soil-amendments-3.pdf

Clay-like soils should only be worked after they have been allowed to become relatively dry, in my modified Mediterranean climate this might not be until July or August on some sites.

Tilling organic matter into soil is bad advice. OM needs to stay on the surface of soil.

Paul, where did you get this piece of advice? Can you back it up or provide a source? Please take a look at the photo of my native soil -- the orange clay on the right gets loads of OM annually (leaves and grass clippings), but only on the surface. It supports bermuda grass and weeds. Can you imagine sticking a small seedling there, or spreading seeds? The dark friable soil on the left was created by digging in OM over the last seven years. I'll stick with what works...

Mulching is not amending (the digging in of compost or sand etc.), vegetable gardening (using annual or biennial kinds) is not decorative planting of long term plants - see article at above link.

@sylwia, you wrote "the dips themselves are right around the house walls and all the rain water is pooling there to the point I have a little tiny pond there when spring rains come." I had this in a few spots, and I added several inches of wood chips to those areas - no more pools. And it's not that the water is pooling there 'under' the wood chips. I had to add another inch or so after it settled a bit, but that was only to top it up. Whether the chips are buffering the water or helping drainage, I don't really care - it works. Wood chips and the like are easy to source, cheap, and they work. If you're not trying to make it look like a football pitch or golf course lawn, you can choose plants that like that mixed environment.

I don't fully understand all your plans but I think your plan to mix all the soil and clay and compost is more work than necessary. Add organic matter everywhere; add more and thicker layers including some 'soil' if you want where it's pooling; try to plant some staff (daikon radish?) that will put down deep roots. Wood chips, sawdust, compost, whatever can be laid on top and will still help.

Yes, organic matter will decompose and settle and you will want to add more in future; I don't find that's a big deal.

It would be quite a big deal to re-amend a lawn or beds of trees, shrubs and other long term plants - these would all have to be dug up and started over. Top dressing a lawn or mulching planted beds of course is another matter.

Most of the time in nature topsoil is built from organic debris falling on top of subsoil. Or starts out as mud deposited by water, which eventually retreats from the site (or is removed by diking etc.). The soil system is generally organized to process fresh or decomposing organic material on or near the surface, and not well below it.

I really have nothing growing in the spot I want to work on. The low spots are sloping a total of 9 inches from a high spot in the middle of the yard that is 15 feet away. it is not a small dip. imagine your house sitting in a valley and your rain water draining towards the house. I cannot imagine trying to work seeds into the compacted soil my backyard is right now. In order to fix the grading, i need to add up to 9 inches around the house and grade away from it, i calculated i need 5 cubic yards of soil to level out to the high spot and slope the yard away. I could just dump the soil into that valley around the house and be done. but then I don't think I will have any luck growing any kind of grass or seeds into the existing compacted soil.

You may not need to entirely level the plot, just improve the soil in those spots or add a layer of mulch so that water drains or is at least buffered (absorbed/released slowly). I'd start with smaller amounts and not think you have to put down 5 yards all at once. Keep in mind any improvement to soil from mulch will take a little while.

As I mentioned above I just did several inches of wood chips in area where water pooled - and that spot is near trees and at a low point, down a slope, probably a foot and a half lower than near higher spots. I did not do any levelling out (not practical); indeed I put wood chips in various places around and other mulch/compost widely so that the soil all over would buffer/drain better.

Hi FM,

I gardened in clay soil and love it. Organic amendments need Oxygen to break down. If OM is buried under clay, it won’t break down. Partially broken down OM contains organic acids such as acetic acid, butyric acid, oxalic acid, that prevent seed germination and root growth.

OM can be mixed in the top 1-2” of mineral soil but I would also cover that with another 2” of compost.

Good luck!

thanks, I guess I will skip mixing the soil but loosen it up and put the top soil on top. I do want to level out the yard and slope away from the house. Having water drain towards the house is just bad and can cause a lot of problems. The dirt is delivered so I got to use it. I appreciate everyone's input on this matter.

I had a similar issue and regraded the area by hand. I had much less of an issue with a 9" hill 15' away, but if possible i would try to regrade that hill, not add soil. Unless the missing soil has eroded to somewhere far away, I have read it is generally not advisable to raise the grade a large amount against your foundation.

Try to regrade the dirt to move the low spot further away from your foundation and sloping away along the length of the hill if you cant regrade the hill.

I wish I had a picture of the before. The problem was "missing dirt" along the foundation. I basically filled in what was missing. The "hill" is really not a hill but the high point of the backyard and then suddenly a whole bunch of dirt took off. I have no idea why it was missing, THe AC and everything around the back settled 9 inches lower. I wonder if over the years dirt just settled or washed away. There was also a very big self seeded tree right against the property that was removed. now that I started adding the 5 cubic yards it almost seems as if I will need even more to fill in. I will post a picture when I get a chance.

Yes, it sounds like the soil is subsiding. That’s a little scary. Very smart of you to fix the problem.