Fall leaves in place of wood chips?

So, this whole year I've been building/improving my already decent garden soil with wood chips & bark from my firewood chopping, as well as simply broadcasting all of my kitchen scraps over the surface.  Most of this consists of things like produce trimmings, banana peels, melon rinds, and a lot of pumpkin/squash rinds (without seeds).  Also, grass clippings, corn stalks/cobs, and melon vines have been chopped up and added.  All of these amendments have been evenly spread around the plot, but on the surface only.  I did plant legumes as an end of season nitrogen booster for next springs crop.  At this time, I have a lead on a bunch more pumpkins to add, but we'll see if it pans out.  I'm feeling pretty good about these improvements for the first year, but I grew up rototilling the family garden plot, and am having a hard time truly seeing why the layered decomposition method is superior to using a rototiller to incorporate all of these surface level nutrients down where the roots will be?

I've raked fall leaves into garden plots before as an insulative layer for my perennial fruits, and also mulched them up with a lawnmower in a garden bed the way people use straw, left them over winter, then tilled under in spring with great results of decomposition.  In my area the glacial soil is fertile, but I try to put more back into it than I take out.  

Now to the question of this post...can you have too thick of a layer of leaves on the surface of the plot?  If so, what happens?  I can see the leaves getting compacted by the weight of the snow, and creating a layer a couple inches thick in which leaf mold and earthworms thrive.  You'd still have to move them away from where you are planting in the soil come spring, but so far those aren't really negatives for me.  As I said, I'm trying to give this layered no-till thing a reasonable shot, but as healthy as the soil would be, I do worry about compaction inhibiting root growth as compared to loose aerated (tilled) soil for seedlings.  Also, has anyone experienced bitter flavors on root vegetables from excess tannins leaching from the leaves?  

I'm interested to see the replies you get. My impression is that there's no credible down-side to leaves in the quantity that you're talking about. I've been putting on all the organics (wood chips, leaves, hay) that I can scrounge together with my time and dollar budget.

So far the only "downside" I see from several inches of chopped leaves in my beds is that slows down soil warm up a bit.   My mulched beds are still frosty under the leaves with chunks of ice,  while my beds that were mulched just with screened compost are warmed up and workable sooner.   If you are impatient gardener in the spring like I am, that might be frustrating lol.   But it's only a couple weeks difference, and by the time it all really warms up,  worms have become active and most of my leaf cover has disappeared and been incorporated.  

Cy,

I too have heavy, hard, brown clay soil, and thanks to my neighbors I also have an abundance of fall Oak leaves--Lots of them.  When first starting out my garden beds I piled on HUGE amounts of leaves--piles 3-4 feet tall that stretched the length of the garden bed.  I then chopped all of those leaves into the ground!  On top of that I brought in still more leaves on top.  I was certain that all these leaves would give me dark, rich soil by spring.  The spring result--dense, hard, clay soil with leaves pushed into it!.

Don't get me wrong, leaves are great for the soil, but I was amazed by how HUGE amounts of leaves can decay into the soil and leave virtually nothing left for all my efforts, or in other cases, how the leaves themselves just stay buried all year long.  They will decay, but don't expect leaves themselves to change the clay soil overnight.  Over a period of years, this can work, but over one season, I have my doubts.

Woodchips on the other hand, are another matter entirely.  I have piled woodchips on the ground and just let them sit (4' tall!) over winter and by spring the bottom layer sorta merges with the soil, with the actual boundary becoming rather vague.  If you can do it, I highly recommend woodchips--lots of them!

Eric

i think how well a big pile of leaves affects your beds depends a lot on how the bed is beforehand. if we’re talking about fairly unimproved clay soil, not much may happen, except at the very interface. with a more established bed with more organic material and larger worm/other invertebrate/fungi diversity and amounts, i frequently get a 6- or 8-inch layer of leaf mulch almost completely migrating into the soil over the winter, leaving very little on the surface by spring (they’re not blowing away). i don’t think there’s an amount where there’s too many leaves piled up until you get the point where the amount doesn’t let rain/melting snow get all the way through, which in some circumstances can leave the soil quite dry underneath (which will also slow down the speed at which the organic material will be taken into the soil).

definitely never experienced bitterness from tannins originating in leaves, and i’ve used massive amounts of leaves at times.

On my rocky clay filled lot,I gave up improving the soil with carbon and began replacing it.
Even after huge piles of chips decayed on top, the soil beneath was meh.

Now I pile leaves into a raised bed and use the resulting leaf mold as my soil.
I usually have wood scraps in the base, I add to the beds each fall and I use lots of urine on them over the winter.

I planted in pockets of compost from the chicken run and the plans find what they need from there.
Tomatoes and squash love it.
Potatoes do ok, but I rarely harvest them ,  they are more like cover crop.



I'm careful about the contaminants in my soil, but I do feed the weeds from outside the beds to the berry bush's and trees that are on the plot.
Each of these gets their own compost pile right near the trunk, and gets fed leaves, urine and weeds.

Hi Cy,
Whenever I have put leaves on my garden in the fall, there is nothing noticeable left when I am ready to plant in the spring.

Thanks everyone for the info.  I do like the effect grass clippings give me, but we'll see how much more organic material I can get to give me a decent layer of moisture retention, soil warmth, reasonable decomposition layer, and weed suppression come spring.  I'm done splitting wood for awhile, so I don't have that source of wood chips anymore.  I will say some nice tree bark that comes off in sheets make a nice walkway between rows & holds moisture pretty well.

I also garden in clay soil. Here, if I cover my beds in 6 inches of leaves, I still have plenty to use as mulch through mid summer. These are large oak leaves with a scattering of pine needles. I tend to rake them off into the paths in spring. Once my plants have sprouted, and are of size, I pull the leaves back up on the beds for mulch.

Improvement of  soil is happening, slow and steadily.

Yeah I want to kind of echo greg mosser. What's your detritivore population like? I'm talking about things like woodlice/roly-poly/pill bugs, earthworms, and snails? If you have a lot of those then your leaves will disappear quickly and you'll get lots of bug poop, which is awesome. If you have a few of these things, then you're going to have a lot more after piling on lots of leaves. If you have none of these, then it might take longer for microbiota to do their wonders.

Cy said, "Now to the question of this post...can you have too thick of a layer of leaves on the surface of the plot?  If so, what happens?

Leaves might offer a mulch to suppress weeds and they will eventually decompose over time.  The leaves will pack down and keep sun and air from the soil.

Woodchips will last longer and have the advantage over leaves for microbial action.

Since you have been using woodchips you will probably see the difference so this might be a good experiment.

Cy,

Upon further thought, I wanted to echo what Greg and Anne mentioned—the soil microbiology is going to determine your soil fertility far more than your soil chemistry.  First some context though.

I used to think of soil as being something like brown play-dough, something that could be molded, squished, beaten, etc. with no ill effects. My garden beds flank my driveway which I put in during house construction.  The topsoil for the driveway was scraped off (and is still in an out of the way pile 18 years later!) and  gravel was laid down.  

As construction neared a fever pitch in the last 6-8 weeks, it started to rain and didn’t stop.  Dozens of trucks parked parallel to the driveway, churning up mud and obliterating what little vegetation was there.  And the water drowned out any attempt at vegetative regrowth.  On the day I moved in, the whole 450’+ driveway was a muddy mess 2” deep or more!  My father was coming to help us move wand I was warning him about the mud by telling him that it looked like pictures of the Wester Front in WWI (LOTS of mud!).  He didn’t believe me till he saw the driveway and we deemed it impassible by the heavily laden moving van and minivans!  We had our contractor lay down a new layer of fresh gravel just to be able to get access to the house.  Fortunately, near the house I had made a series of walkways with pallets left over from construction.

My point in all of this is that the ground where I planted my gardens was thoroughly abused—beaten by trucks rutting up sopping wet clay soil.  Any soil organisms, such as earthworms, either died outright or got well out of the way—there was nothing left for them where the ground was being beaten up.

When I went about making my garden beds I placed them where they were convenient, but the ground was essentially sterilized.  I was in my pre-Permies days and viewed soils as collections of chemicals, not biology so I did what was normal for me—I “loosened” the soil by running a tiller through it, further damaging it and scaring away the earthworms.  I then tried tilling in huge volumes of leaves thinking that would change things overnight.  Of course it didn’t, there was nothing in the soil to decompose the leaves!  My soil turned to a sort of clay-and-leaf paper machet.

I didn’t give up on leaves or planting, but I did eventually retire and sell the tiller and things changed.  Soil life came back to my garden beds.  I still collected leaves, but I just piled them on and left them there where finally they started to decompose.  My soil very slowly darkened.  But by far the best thing I ever did for my garden soil was to dump a bunch of woodchips on the beds and let them sit over winter.  By spring it was already evident that the soil and chips had merged to the point of there being no clear line.

I exponentially expanded my fertility by further decomposing those woodchips with Wine Cap mushrooms.  This experience radically changed the way I see soil fertility.  I no longer look at soil fertility as a matter of chemistry but rather as a matter of soil biology.  Now I have all sorts of soil microbes and earthworms are abundant again.

So what does all this have to do with your garden?  My suggestion is to keep feeding the soil with healthy amounts of organic material.  The leaves are good, but something more substantial is better.  And if you can get biological action going in that organic material, you should be golden!

I hope this helps,

Eric

Thanks Eric,

I've held off on the massive quantity of leaves for the moment, but did add quite a bit of dead/dried plant matter from flower bed cleanup (flower stalks, massive hydrangea flower heads, etc.)  

As usual, the plans I made have flexed to a different direction called "opportunity".  By that I mean, I have been scoring lots of discarded pumpkins lately, and now my entire plot is covered in pumpkin chunks (almost entirely heirloom types with hard rinds/shells).  There's almost nowhere to step that isn't covered in pumpkin rinds.  I'm essentially treating this plot like a layered compost pile.  Everything is frozen now, but it should all be broken down/absorbed come spring, then I'll put down a layer of straw on top.

I have intentionally broadcasted hundreds of good eating quality, orange fleshed Maxima, Moschata, & Pepo (Sugar Pie Pumpkin) seeds around the plot.  I know that the vast majority won't likely survive, but in all reality, a few of those plants will fill the plot at maturity anyway.  So, the idea is to have the layer of seeds covered by a layer a pumpkin rinds similar to the way natural decomposition of the pumpkin acts as protection & helps seeds survive into "volunteers".  I'll allow the exposure to the elements over winter, knowing I'll lose some seed to freezing temps, birds, rodents, and early germination.  I imagine there will be a lot of sprouts that will be killed off by spring cold snaps without protection, so maybe in March or April, I'll put down a layer of straw to insulate what's left.  Truthfully, I have no idea if any will survive, and I have seeds held in reserve just in case that happens.  However, if any do survive, I'll have the beginnings of hardier varietals.  

Cy Cobb wrote: I have been scoring lots of discarded pumpkins lately

Won't dey be jack-o-lantern varieties? I like your idea of growing them in a pumpkin substrate, the soil will be fertile, but doesn't it make more sense to use the soil to grow a better variety? just keep the seedlings in a nearing frame or inside? You must live somewhere pretty cold or I'm missing something.

Cy,

Good job on the pumpkin residue!  Even if you don’t get pumpkins, all that matter should help out your soil.

Eric

Row morgan,

No jack o lantern seeds. The only seeds there are  heirloom pumpkins/winter squash of good eating quality (Maxima & a few moschata) the only Pepo is the sugar pie pumpkin.

I do have seeds saved back for my reserve stash, but from my research, the ones I broadcasted have a reasonable chance of growing.  If I do happen to get too many for my space, I'll just have to prune or cull.  If you see pearls photo here, you can see how many seeds one squash provides, so this is just a test to see how resilient the seeds are, and as a byproduct, maybe select for the best winter squash to fit my area.

For example, if a few seeds were later in germinating, then there's a high likelihood they would survive the early spring cold snaps before sprouting safely.  It's just an experiment, & may not work... then again,  it makes sense that after a few generations of winter survivors, you'd have seeds that would require more warm days prior to sprouting. Just a theory...

https://us-east-2-02860049-view.menlosecurity.com/c/0/i/aHR0cHM6Ly9wZXJtaWVzLmNvbS90Lzc1MzUxL2EvMTk1MzU5L0JsdWUtSHViYmFyZC1TZWVkc18wNTMzLkpQRw~~

I grew a few squash this year.
I didn't plant any, but they grew quite well.
I plan on doing this on purpose going forward.
Similarly, I just gathered the last of the tomatoes, frozen on the vine, to add to my leaf compost beds.

Pretty comfortable saying you can't pile on enough leaves to produce compaction ;) But tilling absolutely does produce compaction, below where the tines work. With tilling you devastate the soil biology in the zone where the tiller is actively working and seal that zone off from the deeper biology with a hardpan compaction layer.

By putting on a deep layer of leaves, you insulate the ground. Helps keep soil biology active for more of whatever cold season you have. It helps with retaining moisture - but, perversely it can also compact into a waterproof layer that keeps water from reaching the soil. Planting through a heavy leaf mulch isn't a great plan ;) What I have learned to do is pile the leaves  on in the fall. Bury the beds, bury the whole garden ;) But in spring, when it stops snowing and turns to rain, rake the leaves off the beds and into the walkways. Trample all over them in the walkways as you sow seeds and transplant starts. Let the rain and the sun reach the soil in the beds while things nd to warm up and get started. And then rake the trampled leaves off the walkways and back into the beds as mulch.

I also think you can never have too many leaves. The only thing that might be an issue (depending on your location and configuration or your garden), is the wind might blow some away. It happened to me.

Besides leaves, I I also use all sorts of vegetation that grows , I do my own version of chop and drop. Recently I heard that even twigs from pruning trees are ok to put down, somehow I never thought of that. Here is Helen Atthowe talking about it: https://youtu.be/mQ9mwiZruSQ.

In drier, lower humidity climates, a thick mat of leaves can be problematic. It can form a thatched roof and water will run right off the area you are trying to improve. It will actually form a hardened top layer from the wet/dry cycle and the leaves underneath will stay dry. When that happens it can take two years or more for any significant degradation to even start. Based on experience, mine go on a rot pile, in the vigorously stirred compost, or get shredded with fresh grass/clover by the hand mower.