A question about amending clay soil...

It's kind of you to remember and inquire. Good timing, too. Yesterday I just put the finishing touches on a "raised lasagna bed," if there is such a thing. Maybe it's a hybrid bed. I am trying to prepare a bed to winter-sow some poppy, lupine, and larkspur seeds. I started with a layer of newspapers, then a layer of six-year-old sawdust, then three layers of lake muck (silt and leaf mold from the flood), and to be fancy I topped it off with three bags of cheap potting soil and one bag of expensive potting soil on the very top. I probably would have left off the potting soil if it were for plants instead of seeds.

What do you think?

Did you alternate your layers of sawdust and silt? It would probably breakdown quicker. I don't have a lot of experience with lasagna method, but having soil as the top layer sounds right to me, for seeds anyway. I 'dabbled' with lasagna bed this spring by screwing together some landscaping timbers in a rectangular shape (it's only 2ft by 6ft) and filling it up with layers, newspaper first, dry leaves, some compost & peat moss, divided into alternating layers but not precise. I sprinkled some alfalfa meal between a couple of the layers. The bed is shallow but I was experimenting. Lettuce and green onions did fine. I plan to add more layers of leaves & compost and cover the whole thing with newspapers over winter to keep the weed seeds from sprouting. I want it for a kitchen garden, but I'm not sure it gets enough sun.

Our situations sound similar! My place doesn't get much sun, either, and I put this new raised bed in front to try to give the seeds as much sun as possible. (The other six raised beds have been very much a matter of trial-and-error. Some plants have done quite well and others, not so much. It's hard to know just exactly how much sun will fall on a certain plot until you try it out. But gradually I'm getting some nice things going.) A good sign that your lettuce and green onions did well!

A question. I had last years leaves in a compost pile, but did not do a good job of turning them at intervals. This summer we had a period of about two months with no rain. When I went to put some of the composted leaves on the raised bed, they were "crusty", for lack of a better word. Do you know if this is "normal", if there is such a thing? Do you think they are usable?

I never turn mine, I'm too lazy. I try to remember to water it if the weather is dry. It will still turn into compost eventually, no matter what you do. It works from the inside out. So on the outside it will look like leaves, grass clippings or whatever. I scrape that off and find finished compost underneath. Then I use the crusty stuff as the start of new pile and throw on new clippings, leaves, whatever. I also throw on a sprinkling of garden soil once in awhile to get those micro-organisms working in there too.

You know, that's about what I figured. It is, after all, a natural progress. You don't have to work it like a combination to a bank vault. And it DID smell like dirt, which is what I was aiming for. Rather a comforting thought that the process will take place in spite of me!

My layers in the raised bed are probably too thick. I should have alternated them more in thinner layers and will remember next time.

Thanks for the encouragement!

>> My layers in the raised bed are probably too thick

Is the leaf mold mostly crumbled and likely to drain and be porous, or are there big whole leaves that might plaster together and block the passage of water and air?

If it does matter, you could push a pitchfork's tines mostly under the soil layer, and mix the lower layers a little, here and there, by using the fork like a lever with the fulcrum in or under the soil layer. Punch some holes in the leaves if they mat together. (But that sounds tiring.)

Even more laborious would be to rake the soil to one side and "plow" the lower layers by dragging a pick or mattock through them. Probably not necessary!

Best of all, with the silt and decomposing leaf mold on top of the sawdust, if any rain penetrates, it will tend to wash some silt and humus particles down into the sawdust for you - no-effort mixing!

Corey

Thank you for the tips. I can tell you've been there!

The part I've dug so far is mostly dry and crusty, not wet and matted. I put some on an exposed slope last week to try to amend the soil there. At first it looked fairly horrible lying there, but when the rain came it turned rich and dark so I think it will work just fine.

A couple of things I just haven't mastered (if you don't mind coaching me a little further.) I've been keeping two compost piles at opposite ends of the place. One is mostly leaves. The real reason I don't turn it often is that it is behind the woodpile and it gets pretty snaky out there in the summer.

The other one is slightly uphill of three magnolia babies. My original plan was to alternate using from and piling onto the beds every six months or so. But like I say, it turns out I am scared to go to the leave compost area in the summer, so it hasn't been properly added to. One benefit that has already happened, though, is that "juice" from the second bed seems to leach down to the magnolias, because they are doing VERY well.

At both beds the wire fences keep getting knocked down by dogs or critters, so they basically are just piles.

Now that we have consistently cold weather, it's safe to walk back to the leaf bed, so I guess I can start adding kitchen items back there. Maybe I will be able to alternate after all.

Do you think this is a workable set-up, or how should I adjust it?

Boy, it takes corncobs forever to rot, doesn't it?

I guess I would expect some kinds of leaves (especially oak) to be rather slow to decompose, especially if they were not combined with something green, or chopped some with a lawn mower first. Even a little lawn fertilizer could supply N for composting dry leaves, but some are dead-set against using any chemical fertilizer.

One friend of mine set aside all his oak leaves in bags for one year "to let the tannin decompose". He would turn the whole leaves under soil the second year.

He didn't actually compost them first, and eventually gave up on just turning them into his garden because big whole leaves make sowing tough! By then his garden had so much accumulated organic matter that it got by with just added grass clippings as compost or mulch.

I kept telling him that he "should" have shredded and composted the leaves before adding them, but he was getting good enough results to satisfy him, and was strongly against anything like unnecessary work..

Are you keeping one heap behind the woodpile so it is out of sight? A compost heap that you can't get at during the summer sounds inconvenient.

Personally I would not lean it AGAINST the wood pile, or it will hold moisture and bugs against the wood, and encourage the wood to rot. One place I lived had had a woodpile rotting in one place, apparently for years before we moved in. The bottom layers were mushy by the time I got down to them, just low-N compost which was good for the garden and flowerbeds, but not the fireplace.

>> it takes corncobs forever to rot,

Yeah!

A friend used to throw all his kitchen garbage onto a pile, but his grapefruit rinds and corncobs looked like anthropologists 100 years from then would be able to catalog his dietary habits. If I put them in, I would rather chop them into smaller pieces first ... but I just like knives and cleavers and, actually, never eat grapefruit or cook corn on the cob for myself! If apples or carrots get too soft in my refridgerator, I'll slice them into 1/4s or slices before adding them to the heap. Even so, carrots are very slow to be consumed, and remain embarssingly bright orange for a long time.

Maybe, when most of your pile has composted, and you pull off the crusty outer layers to "demote" them to a pile that is still being built up, you might also rake out the big pieces that are not decomposing fast enough. Either just demote them to the other pile for another year of rotting, or chop them a bit with a shovel, or bash them against a hard surface with a length of firewood, to squish them and break them up a little.

Or, like my friend who avoids unnecessary work: just wait and let bacteria and worms do the hard parts for you.

Corey

This is such a wonderful website with people like you to kindly share a wealth of information. Thank you! I have learned so much!

I'm kind of laughing to myself, too, or at myself, that I never put two and two together and realized that, since I live in the middle of an oak forest, which is actually called White Oak Creek, that maybe there ARE in fact a lot of extremely sturdy oak leaves descending upon me each year and that, since they are not small and flimsy like willow or elm leaves - - that just maybe it would be expected that it would take the compost pile a while to decompose.

And yes, it would probably make the most sense to move one of the piles to an area that is more accessible in the summer so that whenever I just particularly feel like going out to turn over the compost pile, I will be able to reach it without fear of being fanged by something.

Thank you for your generous patience. Next year is going to be the best gardening year ever.

PS I am not complaining about the oak leaves. They are very beautiful and quite silky in texture and they look great on the paths and driveway, from whence they are usually disintegrated by spring.

I have two piles, no enclosures, just piles. They aren't exactly hidden, but they are 'obscure'. One is near the house and one is out back, up a hill. My stuff gets thrown on the closest pile to where I'm working because I don't want to drag it up or down hill. The one near the house gets kitchen stuff and leaves & trimmings.

As Rick says, if you want to go to the trouble, things will decompose faster if you chop them up into smaller pieces. Egg shells also take a long time if you don't crush them first. For fun, google 163 things you can compost. Some of the items are quite funny.

Thank you very much, I just hope that some of my opinions are accurate!

>> And yes, it would probably make the most sense to move one of the piles

I do many garden things that people tell me I "should" do differently, becuase they do it differently and they like their method. Bah! Try something different from the conventional wisdom, that's how we learn. You might discover some totally unexpected interaction between snakes and oak leaves that no one on the planet ever learned. (Just don't get bitten!)

I never thought to ask if they were OAK leaves. They will be slow. I think that "tannin" is the culprit. Chopping ahead of time helps almost anything to compost faster.

Two piles sounds good - give the oak leaves 12 - 18 or even 24 months. You might want one or more "slow piles" just for mostly oak leaves. Having them out of sight and not blowing around seems desirable.

But if you have other compostable things, one "fast pile" migth be desirable.

Or merge one-year-old oak leaves with your greener "fast pile" and expect that combination to cook down in 1-2 seasons.

If you go to the "Soil and Composting" forum, you will meet the REAL experts, who can tell you more about oak leaves, but sometimes I think some of them make religions out of their composting methods.

"Hot" vs "Cold" compost piles, people who love worms more than flowers, technically inclined people with compost thermometers, frequent mixing vs layering, and particularly the fundmentalist sects of "Lasagna Gardening" and "Bio-Organic Principles" ... I once offended the latter two groups and it was like bringing ham and cheese sandwiches to a Synagog picnic!

I think that almost anything works, just some things work faster.

Many of them caution people against letting weed seeds or herbicides into their piles: I don't worry about weeds because I already have so many weeds everywhere, what's a few more?

I have more experience composting than I do gardening, because as a kid I mowed, raked and composted, but Mom did all the real gardening. I know things that will slow a pile down, like not-enough-green stuff or all-acid-pine needles.

Thanks again for the compliment. Happy composting!

Corey

I think someone said "anything but meat or grease". And others said that even those could be composted IF you can keep pests out of the pile, and it has a hot core that you can bury the scraps in.

Weed seeds and herbicides are also things to keep out.

I don't like rocks in my heap! Plus, they are very slow to decompose. ;-)

Corey

Hey, shune - how's the fall in Burien? In Olympia I made a big hole under the rhododendrons with a posthole digger, and poured wet slop from the kitchen into it almost daily. The rhododendrons got BIG. I miss them.

But I couldn't do that here. We already have too many creatures coming and going in the night.

Hi Rebecca, Fall has been wet... the leaves aren't quite all gone off the trees yet, and today we have snow, so it is also cold. On vacation from work this week so I don't have to drive in it. Clever planning on my part! hee hee Hopefully it will be gone soon.

Snow?, she said hopefully.

Yes, we have snow. And it's cold. I would send it over if I could. I don't mind snow if I don't have to go anywhere. But as soon as I'm stuck inside, I can think of 100 places to go. What kind of weather are you having?

Hoping for snow.

I have a poorly draining bed that is probably high in clay; heavy, compacted, no sign of worms. It's full of one to two-year-old perennials. So the soil has been amended a bit with each set of plantings, but it's clearly not great soil. Is it possible to add aeration and some kind of composting BETWEEN the young plants? There's still about 6" of space between each plant (a little less than in the photo here which was taken 3 weeks ago). Any suggestion would be great. I feel so bad to not have amended the soil well enough before buying and planting dozens of plants!

Everyone tells me that if you add organic matter on top of the soil, like compost or fine mulch, it will decompose and filter down. Worms will gradually come and help mix it in. I think I've seen worms attracted to the "drippings" from my compost heap that leans against my pile of clay.

Frost heaves and dry-wet cycles also cause clay to expand and contract, hopefully mixing things over enough time. Roots will drive channels into it that let air in and water out (gradually).

Just don't let raw manure touch plant stems.

I like to compost things in a compost heap, and then put the finished compost around the plants, personally.

Apparently many worms are coffee addicts, becuase they do seem to come to wherever you put coffee grounds.

I really like the idea that I read very recently, that organic matter (compost) is the "food" in soil. Why should worms go where there is no food for them?

I like to expand that idea, and reflect that soil needs everything that any living thing needs: food, water and air (and coffee).

Worms won't go into totally water-logged (anaerobic) soil.
Worms won't go into totally dry soil.
And, probably, no organic matter at all means no worms at all.

I also believe that, if you drain the water out of the soil BELOW the bed, the bed and its base will drain down, however slowly, and let some air into the soil during dry spells. Surely that has to encourage the worms?

I've also read that long-time perennial gardeners bide their time for 3-5 years, until they need to dig up and divide many of the things in one part of a bed. Then, they divide and move EVERYTHING in that part of the bed somewhere else, maybe some into pots, maybe other beds, maybe only temporarily.

That gives them the chance to work in all the compost and other amendments they've been saving up. I suppose you could even give that bed a deep-rooted cover crop rotation!

Then they can move the same or other perennials back in.

I'm still early in the process of putting bulbs and other perennials into new raised beds, and I have the same problem: I was impatient, and didn't have much compost, pine bark or sand available. I'll be top-dressing with compost and maybe biosolids for a few years, then plan to dig up the bulbs and totally replace the soil. By then I hope to have amended WELL all the clay I've been digging piling up and screening.

Corey

Thank you Corey, for giving me a way forward! Patience is the key I suppose. Might it also be helpful to dig some small but deep holes between the plants and add peat moss, then maybe use a pitchfork to break the soil up a bit?

That is exactly what I do. I have a little cultivator, with three prongs on one side and a hoe blade on the other side - about 1/3rd or 1/4 as wide as a normal hoe. And a sharpshooter spade (trenching spade?) - narrow, flat and long.

I think it accelarates the process, at the risk of cutting some roots. But most plants seem able to deal with a little root trimming, so the benefit exceeds the drawback..

Especially if your subsoil has any drainge straight down, having some holes through the clay layer should improve the drainage of the whole bed. And if not, you at least have some columns of serated soil going deep, to encourage worms to visit, and maybe drill their way from colimn to column. Don't underestimate coffee grounds!

I see the main goal as increasing the depth of the aerated root zone faster than worms would by themselves.

My "clay philosophy" has evolved into something like:

1. provide some external drainage "away and down" - below grade - to let water out from under the bed, and let air into the deep soil.

2. Set up raised walls, 6-16" above grade, depending on how much good soil and amendments I have

3. Maybe: excavate the bed 6-12" below grade, screening out big rocks and removing the worst clay. This depeends on time and energy as well as how much soil amendment I have in the budget.

4. Create some mechanical soil structure for roots below grade (very coarse sand/grit, pine bark, compost). Try to get some air in there even before the soil becomes decent. Avoid compaction.

5. Add better soil on top, and amend enough of the top layer that SOMETHING will grow and put down roots. Drainage is better if you have a gradual transition between the top "half-decent soil", and the deeper "crummy clay". NEVER walk on it.

Then repeat 6 & 7:

6. grow there, top dressing with lots of organic matter and mulch for several years

7. come back a few years later, turn more OM under deeply and inspect. Turning and forking may be needed to break up compaction. Pine bark breaks down over several years, and OM is digested to CO2, so you need to replenish it.

(Meanwhile, start other RBs, and keep trying to find cheaper sources of compost!)

Hopefully, after a few cycles of that, the OM will build up and trickle down into the deep soil enough to maintain it, and roots and worms and structure will remove the need to correct compaction by turning deeply every few years.

That's my theory, anyway.

Corey

At this point worms are a mixed blessing, I conclude. I have one raised bed where I have more or less adjusted the soil to where plants are happy. And there are worms Grandma. I was happy to see the worms until I realized they were attracting the armadillo. At first the armadillo could be deterred by deer repellent, but as the worms grew more abundant and he got hungrier, the armadillo came in anyway, and uprooted my squash and cleome seedlings and as collateral damage sideswiped the new raspberry bush. I unrolled some wire fencing over the bed. He pushed it aside and uprooted the same poor seedlings.

After the third attack in as many nights I decided we could no longer cohabit and have ordered a live trap.

Clay is tough to deal with, it's a lot easier amending sand. What you would want your dirt to be is around 17% clay, 40% silt, and the rest sand (under 50%). Give or take, but clay needs to be less than 25% of the mixture while sand & silt can be as high as 50%.

In short to amend 1" of clay you'd need 4" of sand/silt to create 5" of good stuff, while to amend sand one only needs 1" of clay mixed in. How to mix it all together properly I have no idea. If you do it wrong, you can create concrete. if you do it right, you won't be depending so much on organic matter. A raised bed or lasagna gardening sounds good to me.