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tilling, sheet mulching pros and cons  RSS feed

 
Gilbert Fritz
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Location: Denver, CO
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The St. Isidore society is starting a second community farm. One our last one, our first step was to lay sheet mulch over undisturbed sod. That worked wonderfully, as far as plant growth went, and OK as far as weed suppression went. We used wood chips and horse manure over cardboard.

For this next site, we are looking at several different options for soil prep. Please help me sort through the pros and cons. Remember, it has to be something that yields a usable plot in a week or so, and has to be applicable to half an acre.

We could do the cardboard, wood chip, and horse manure stye sheet mulching. (These are the only cheap organic matter options in the area that are likely to be uncontaminated.)

Pros: proven yields, water retention, low tech, cheap

Cons: raw manure will make it dangerous to plant greens. (We can't run that risk on a community farm) Small seeds will flounder in the mulch. Root crops are out for both reasons.

We could till, incorporating soil amendments, and then spread six inches of wood chips. Then we would plant into the soil through the wood chips. In succeeding years, this would be left undisturbed and planted just like a sheet mulch.

Pros: larger range of crops available, less danger of contamination by herbicides or E. coli from the manure, greater rooting depth and access to soil minerals, fast

Cons: soil disturbance, moderate cost

We could plow, disc, and then spread wood chips, as above

Pros: same as above

Cons: slightly more soil disturbance the tilling (We would be tilling very shallowly) slightly more cost

We could try to hot compost manure, and then use it with wood chips in the sheet mulches.

Pros: low soil disturbance, water retention, less contamination potential

Cons: LOTS more work, danger of the piles not heating up so that one of the other options has to be employed, still some danger of contamination from pile edges since we have no high tech machinery, shallow rooting depth.

What would you all advise?

 
Joseph Lofthouse
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Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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The reason that I don't apply mulches or wood chips or other organic matter to my farm is that it's unaffordable. Small-scale growers can pretty much do anything that they want without calculating costs for labor or materials. You ever tried to gather together enough cardboard to cover 22,000 square feet? That's about 4400 boxes, or a pile 140 feet tall if broke down and laid out flat. That's around 20 to 40 pickup trucks full of boxes. You priced gasoline lately? Who can even supply that quantity of boxes? Putting a 4" layer of organic material on a half acre garden requires 272 cubic yards. The cheapest organic material around here costs about $25 per cubic yard delivered, so that works out to around $7000 per half acre. (6" = 407 cubic yards = $10,000.) Have you calculated how much labor it takes to spread out enough wood chips to cover 22,000 square feet? Last time I did the math for my 4 acre garden, it would have taken longer than the available growing season. I suppose that if I had the money to buy the materials that I could pay to have the supplier spread them for me as well.

Renting a tractor and tilling the field would cost perhaps $200 including fuel. Some people might badmouth plowing the soil, but I presume that the reason that tilling has survived for 10,000 years is because it has proven itself to be inexpensive and productive. I suppose that tilling has shown itself to be sustainable, because since time immemorial farmers have tilled their fields: Regardless of how bad the economy is. Regardless of availability of fossil fuels. Regardless of social decay or warlords. Regardless of environmentalists or mycologists.
 
Gilbert Fritz
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Location: Denver, CO
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Do you think tilling or plowing would be better? Cost is not that important. Which would do a better job killing the grass and getting things going? We will probably do one or the other, due to logistic hassles of getting mulch right away. Then we can mulch the beds over time.

We did gather enough cardboard and wood chips last year to do 5-6 thousand square feet. The wood chips and leaves were free, and the companies were only too glad to dump them. The manure cost 80 dollars for delivery of 8 yards, and then we got another 8 yards delivered free from another stable. The cardboard mostly came from appliance and bike places. It was quite a lot!

Then we rented a tiller and did another 4-5 thousand square feet. That was much harder work then spreading mulch, and the weeds came back like I couldn't believe. And nothing did as well as in the sheet mulch beds.

However, I do get your point. I live in one of the biggest metro areas of the USA, and so logistics are considerably easier for me. I am generally saving people from having to pay a dumping fee.

But as oil becomes less available, this supply will dry up. Organic materials will need to stay where they were generated to improve the local soils. I am hoping to import organic material a few times at the beginning, and then use cover crops to maintain the land, either with a permanent cover of clover or by crimping down winter crops to form a mulch. Much less work, and if I can save my own seeds, no cost.
 
R Scott
Posts: 3349
Location: Kansas Zone 6a
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You have laid out the pros and cons for the most part, and I don't know enough about the tools and labor available to add much.

My choice is to use whatever machine you have or can rent to make raised beds. Till or plow and move the pathway dirt onto the beds. Fill the path with mulch to hold water and limit mud. It will compost for next year.

Hot compost is a lot of work at that scale. But is possible without machines using a lot of Berkeley piles. Do that and top dress the beds throughout the year, it doesn't have to all get incorporated now.

I don't know you weed seed load in the soil. Being able to tarp the beds for a couple weeks helps germinate the weeds so you can flame them before your crop goes in or comes up.
 
Matt Smaus
Posts: 37
Location: Minneapolis, MN
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Plowing works way better on sod or turf than rototilling does. There is no harm in doing it once, and you can plow shallowly just to flip the turf over, letting it decompose. Rototilling leaves a lot of living chunks of grass that will re-establish. That said, any of these options require more than a week. You need to let the sod decompose whether you flip it over, sheet mulch it, or cover it in black plastic, and that takes 3-4 weeks (faster when the weather is warmer).

If you really need to plant right away, I would rent a mechanical sod remover and roll the whole field up in strips. Lay the sod upside down in stacks in a corner and cover it to compost it--the sod will decompose into perfect potting soil, or you can add it back to the field later. Anyway, remove the sod and then put FINISHED compost and other amendments (lime? other minerals?) on the field. If you want to plant in it this year, I wouldn't put anything hot on it. Wait till fall if you want to do that. I'd put finished compost down and then rototill the compost and amendments into the top 6". If you can get a broadfork in to open up some deeper channels, all the better. Or, if you can find a tractor operator to come into the city, chisel plow it as deep as you can to open up the lower layers.

You only need to do this once. If you establish permanent beds, plant roots should be able to keep them loose enough, especially if you cover crop in deep rooted clovers or tillage radish from time to time. Or you can broadfork occasionally. Also, if you plan to grow annuals, I would stay away from wood chips. I know a lot of people love to plant in would chips because it makes everything easy, but they can harbor slugs and sow bugs which is alright for perennials but can be devastating to vegetables. Their decomposition can leed to mineral imbalances over time, too, at least as far as vegetables are concerned, and depending on your soil type.
 
Gilbert Fritz
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Location: Denver, CO
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Well, it is not sod, just chunks of buffalo grass. Also, I can afford to wait several weeks, just not months. We can rent a plow cheaper then a rototiller, (the tractor operator will do it free) so we will probably do that.

We can't afford finished compost, so we will probably just have to do with soil amendments and the decomposing grass for organic matter, this first year, till we get our composting system on track.

Also, wood chips worked really well for us last year. I think in a dry climate there are less pest problems with it.



But I will leave many beds without it, to sow greens and root crops that don't do well in deep mulch. Tomatoes, squash, etc. seem to love it.

I don't think I have a heavy seed load, just buffalo grass that has been mowed for a long time.
 
Marianne Cicala
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We have a for profit farm, 5 acres with fruit trees, berries, herb, perennials as well as seasonal annuals. I am very pro sheet mulch (newspaper not cardboard) - when we were initially establishing the beds, which are now no till, we did break up the soil with a plow and then, sculpted the permanent beds which are raised above the walking paths by 18" - 20". Granted it took a very full week to top the beds with newspaper (in the rain which worked extremely well), then the soil that was removed to the hard-pan for walking paths (which we eventually covered with old straw) was shoveled on top of the paper. I did top that with compost and planted. The 1st spring season was surprisingly prolific even with the disturbed soil. We chop the tops off of our annual crops when they are spent and compost that, leaving the roots in place to help hold the shape of the beds as well as leave a lot of organic material in the soil to breakdown and feed future crops. The summer crops were bountiful as well the fall crops. In mid winter, we spread compost on top of the beds & just leave it. I add every bit of organic material I can from the farm, including year old chicken litter. We plant very tightly, so weeds are not a problem. I find that the newspaper helps bring in earthworms in droves and if nothing else, that would make a fan out of me. The best thing for us, is that once this was done - the sheet mulch, permanent beds etc our work is minimal season over season. When we thaw out and seed for spring crops, we will simply rake the top of the beds smooth (from freeze/thaw heave) and plant. It makes spring growing nothing but a pleasure and do not become a slave to gardens that are too wet to plow or till - I only need a couple of dry inches to plant seeds. This is a picture from the 1st year (August) and I could not be happier with the results. The fruit trees had been in the ground for about 6 years prior to the fruit forest conversion.
garden.jpg
[Thumbnail for garden.jpg]
 
R Scott
Posts: 3349
Location: Kansas Zone 6a
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In that case plow it asap, form the beds, and cover them with tarps. The heat will germinate seeds and help speed up decomposition.

Rent or buy a cheap subsoiler ($200 for a new single point one from tractor supply) and work the ground DEEP before you plow. One run down the center of a 30" bed, two runs for a 48" bed. Then broadfork in future years.
 
Tim Wilkinson
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Gilbert,

Six inches of wood mulch is way too much. You will have all kinds of mold, fungus, and diseases growing in there and it could become matted down and prevent water from penetrating the soil.
2-3" is best and will save you a lot of money and headaches.
Tim
 
Gilbert Fritz
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Location: Denver, CO
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Thanks for all the advice everyone!

I am glad to hear that a commercial farm uses sheet mulch successfully.

Tim:

We used about a foot of mixed mulch last year (wood chips/ manure, and grass clippings/ shredded leaves.) It worked well. The wood chip mulch worked a lot better then the grass clippings, since the clippings did mat down and also rotted away very quickly, leaving the tomato root balls sticking out. But we had a bountiful year with that setup.

The reason I can't do it this year is due to time constraints as far as harvesting roots and greens from manured beds, and lack of time to get it set up by planting time. (Early crops will be going in in a month's time under row cover.

So I think I will get it plowed, and then transition to sheet mulch/ permanent cover crop beds over time.

R Scott:

I like the tarp idea!

And we do have access to a chisel plow/ sub soiler.
 
Michal Malinowski
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Location: Poland
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Some questions that would help to answer:

1. What do you plan to grow on that land?
2. Where do you want to source the wood chips, compost, manure etc.
3. What equipment and manpower do you have to your disposal?

Renting a tractor and tilling the field would cost perhaps $200 including fuel. Some people might badmouth plowing the soil, but I presume that the reason that tilling has survived for 10,000 years is because it has proven itself to be inexpensive and productive. I suppose that tilling has shown itself to be sustainable, because since time immemorial farmers have tilled their fields: Regardless of how bad the economy is. Regardless of availability of fossil fuels. Regardless of social decay or warlords. Regardless of environmentalists or mycologists.


Same could be said about everything. Ploughing is a practice devastating to the soil's wildlife, and that is a sad fact.

The reason that I don't apply mulches or wood chips or other organic matter to my farm is that it's unaffordable. Small-scale growers can pretty much do anything that they want without calculating costs for labor or materials. You ever tried to gather together enough cardboard to cover 22,000 square feet? That's about 4400 boxes, or a pile 140 feet tall if broke down and laid out flat. That's around 20 to 40 pickup trucks full of boxes. You priced gasoline lately? Who can even supply that quantity of boxes? Putting a 4" layer of organic material on a half acre garden requires 272 cubic yards. The cheapest organic material around here costs about $25 per cubic yard delivered, so that works out to around $7000 per half acre. (6" = 407 cubic yards = $10,000.) Have you calculated how much labor it takes to spread out enough wood chips to cover 22,000 square feet? Last time I did the math for my 4 acre garden, it would have taken longer than the available growing season. I suppose that if I had the money to buy the materials that I could pay to have the supplier spread them for me as well.


That is true. It can be hard to find enough cardboard for the patch between the bads let alone for the whole farm. Not to mention to find enough biomatter. And the biomatter should be sourced from the farm itself if we aim at sustainability. So first we should consider what quantities of biomatter we have to our disposal before choosing the method.
 
Gilbert Fritz
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Location: Denver, CO
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We plan to grow standard vegetables. The wood chips and manure would be delivered, as we did last year. Somebody has a tractor and will help us out with it, but we would have to rent attachments. We have a fair amount of manpower, but not much time till planting time.

Anyway, it may be a moot point, because the weather has been too wet and snowy to get any soil working done. By the time all this melts off and drys out, it will probably be the end of March: planting time. (For cool weather things under row cover.)

I have thought of another strategy: putting down some cardboard with wood chips on top, and laying an inch of purchased compost on top. Quite expensive, but probably doable for a few early crops, till the soil dries out and we can plow.
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