Decomposed wood chips

patty4150(SoCal)July 11, 2007

Hello -

At the (organic) community garden, we have loads of woodchips spread about the paths. Every few months we have a work day and we spread more chips. So now, after years of this, we have applied several feet of wood chips onto the paths, chips which have decomposed in place.

A few of us have been raking back the top layers of chips, and sifting the older layers into a wheelbarrow, and thus "harvesting" a fine, crumbly, springy material. It isn't quite humus (not dark enough or fine enough, and it doesn't cling together so much as spring apart when you squeeze it) but it is fairly broken down, presumably still with lots of lignin and cellulose in it.

One gardener used many wheelbarrows of this to amend a plot which he then planted with corn. Although the material is undeniably a great organic addition (our native soil is heavy alkaline clay), I wondered if it really was providing any nitrogen - and I had reservations that he would have the bumper crop of corn that he wanted.

He has, in fact, had a decent crop of very short corn. It is about five feet tall, but each stalk has two big ears. He planted four varieties (different maturity dates) and all four varieties are short.

Anyway, I lasagna garden, and I am wondering how best to use this sort of wood chip compost material. I plan simply to layer it - but my question is this: Should I consider this material to be a sort of "brown" (like the straw I add to my lasagna), or a "green" (like the coffee grounds I add) or neutral? My best guess is that it is still sort of a brown - that since it comes from wood chips, it is limited for nitrogen as it is decomposed. I *think* the short corn in my neighbor's plot might support that.

The compost from my home bin, which has a variety of input material, I generally consider to be balanced in terms of green-ness/brown-ness (or nitrogen content, as you prefer.)

We have tons of the stuff, and I have had occasional bad luck in the past with going too high on nitrogen in my lasagna beds (and my beets not forming decent roots, as a result, for example.) So, should I try to balance the woodchip stuff with lots of coffee grounds, or not?

Thanks for any insight or experience along these lines -


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billhill(z5 MI - KBG)

The material you describe is a brown. I use similar material in my compost. Add greens and the result is beautiful classic compost. So definitely YES, layer on some greens with this stuff in your beds and you will be happy.

    Bookmark   July 11, 2007 at 12:42PM
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Thanks Bill - I appreciate the feedback -


    Bookmark   July 11, 2007 at 2:11PM
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diggity_ma(5 MA)

As you allude, the problem with wood chips is that they can be very low in nitrogen, and can in fact consume nitrogen from the soil (if mixed in to the soil), thereby starving the plants of nitrogen. It will, of course, eventually balance out. The question is how far along in that process is it? I'd say that fortunately in this case your friend's corn is the canary in the proverbial coal mine. If he can mix this stuff in to the soil and get a decent crop of corn, then that tells me it's probably fine for you to use it too. Now 5' is not super huge for corn, but it's not horrible either. Corn is a heavy feeder, particularly of nitrogen. If he got those results without pumping it full of fertilizer, then I'd say go for it. You might want to verify that particular point with him first though - did he add any additional nitrogen? You may find out that he had to add a bazillion tons of urea to even make it to 5 feet. If that's the case, then throw this stuff in your compost pile, add plenty of grass clippings or another high nitrogen source, and let it cook for a while.


    Bookmark   July 11, 2007 at 2:51PM
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If quack grass is any good indication of whether the digested wood chips are good or not then it is really good stuff because the quack grass around here grows greener and taller when rooted in really old wood chip duff then even in composted soil. Sheep sorrel also grows better in that wood chip duff. I've not ever picked it up and used it in the planting beds because it usually is buried under more wood chips too deeply to dig out.

    Bookmark   July 12, 2007 at 7:14AM
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westy1941(Boulder County, CO)

This blew my mind - I just tore up a wood-chip path that went all around the house (was five years old) - was going to post almost the same questions and saw this. I dumped eight wheelbarrows full under two huge pine trees with branches low enough to hide it (husband is president of the stupid 'association' and we're not 'allowed' to have compost bins). My question has to do with nitrogen also, as I figured it would be needed in this pile. What can I add that won't be too obvious? I want to mix in other components to make a rich humus and know it will not happen quickly. Maybe if I keep turning in stuff this fall and winter it will be good next spring? But what stuff? Grass clippings are hard to come by because a 'service' cuts our lawn. I hate it here.


    Bookmark   July 13, 2007 at 2:38AM
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tsugajunkie z5 SE WI

Yes, nitrogen is what you need. Coffee grounds from starbucks, manure (I'm sure that would go over big with the "ass-ociation") or get the grass from the lawn service. Be careful with the grass though, I'd guess its loaded with chemicals judging by what you've said. Be careful, too, with the mulch piled up on the pines' trunks- that won't do the pines any good as it rots the bark. Good luck with your clandestine composting! Maybe you can start a grass-roots group in your community to ban the banning of compost bins. After all, most communities encourage them.


    Bookmark   July 13, 2007 at 3:10AM
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Hey Westy,

Another green is urine. Depending on how much you hate the rules at your association, peeing in the yard might be what the doctor ordered.....


I've sifted out tons (well, OK, only three wheelbarrows full) at the garden, and it is springy lovely stuff indeed. I layered it onto my garden bed (another way to get around compost bins - you can layer the materials right on the bed for slow decomposition and the worms love it) and I also added starbuck's grounds for a green to balance it out.

I was so excited by the activity, that I then added more compost (from home) and straw. So my beds are a couple inches thicker today than when I posted. :) Isn't it funny how exciting dirt can be?

I also found some pole bean seeds hiding under my bed at home (they had fallen off the nightstand), so I planted those for a late crop - and since beans fix their own nitrogen I just added the decomposed woodchip stuff straight into the soil. I suspect you can do that as well - for any legume - just add the decomposed material (seems best if it is sifted) to the soil and plant any of the beans or peas (they fix their own nitrogen from the air, so you don't need nearly as much in the soil.)

Finally - I love it when I have a question and someone else has just asked the same thing. That happened to me on the veggie forum a few days ago - I was curious about when to plant onion seeds. Someone else asked that very question just hours before I logged on.

    Bookmark   July 13, 2007 at 10:39AM
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westy1941(Boulder County, CO)

I asked my botany professor at Morton Arboretum (I'm going back to school after 50 years) "What is anhydrous ammonia made of and how does it affect crops?" Reason I did is because I read all the time about how totally deficient our agricultural soil is (mass production of our food) Answer: (from Ag Prof): Anhydrous ammonia is a nitrogen fertilizer commonly used on crops such as corn. It is injected into the soil as a fertilizer. Due to the chemistry of anhydrous ammonia, the injection band initially is toxic to plant growth because of high pH. In a relatively short period of time after injection into the soil the ammonia is converted to nitrate and the pH of the injection band decreases. Nitrate is the primary form of nitrogen used by corn from the soil. At this point the corn plant can use the fertilizer and provide higher yields.

Nitrogen is the nutrient which is the most limiting of corn yield on most fields. Nitrogen is needed by the plant because it is a critical component of proteins. Deficiencies affect all aspects of crop growth including chlorophyll production. Plants short on nitrogen are stunted and have a light green color. The exact amount of fertilizer needed depends on the productivity of the soil. Nitrogen fertilizer is not typically applied to soybean. Soybean is a legume plant with the capability of fixing atmospheric nitrogen to meet its nitrogen need. Consequently, farmers do not need to apply fertilizer nitrogen to grow this crop.

Unless you have a clear understanding of the nutrient needs of your soil as well as your PLANT, you can be either wasting your time and/or your money and possibly harming the plant. Agribusiness requires much different methods of growing than does plant culture in gardening."

So I know legumes are capable of fixing atmospheric nitrogen, as are most plants -- especially those not grown in fields which are continually plowed.

We talked about the nutrient-depleted soil from which our mainstay crops grow. Bottom line: grow your own food in soil you make yourself! I have never been more passionate about anything in my entire life. I want to eat REAL vegetables - the kind they grow in Europe. I don't know where to go but it aint HERE. And I want chickens.

I have been using the AACT method of composting (aerated activated compost tea) using worm castings. The worm castings grow microbial organisms within a day or two of 'cooking' in a 25 gallon container with a pump for aeration. It must be applied quickly when finished or the organisms will die as soon as the air is cut off. It is sprayed on foliage and the soil is drenched almost weekly. Since I started this four years ago, I have incredibly friable, sweet and worm-filled soil and have watched my garden explode. I disturb the soil as little as possible - only top dress. And my profs validated this method for me.

After having been further educated by reading some of the info here, I've been scooping up some of the 'natural' mulch on the floor of nearby wooded areas, (the older the better) and topdressing the soil. Also, slowly adding a few different things like alfalfa, corn meal, and/or rice flour also increases microbial organisms. but I want rich friable compost so bad!

Are you serious about Urine? I'm ready to pee everywhere, seriously. What about the pee of dogs and cats that ruins lawn (which is a pathetic waste of land) -- how does this differ from human urine? And what about fish emulsion and/or seaweed products? I realize dairy and meat is a major NO. But what do eggshells provide?

And yes, I keep the piles under both trees far enuf away from the trunk. We have no termites in Illinois anyway - I just think it's better for the trunk to keep it free from suffocating.

I'm sorry this is so long, but I'm still not really clear aout the legume thing. Do I have to actually PLANT them in the compost or can I throw legume leftovers into the pile?
I need a frickin' farm. And he just wants to play golf. It's amazing how 45 years of marriage becomes a whole different ballgame. Too bad I love him - he's a good man - just not a farmer like me.

Thanks for all the help and I apologize for the epistle.


PS Incidentally, I have room for only five tomato plants - enough to warrant an Rx for antidepressants. And my passion is Hosta - 300.

    Bookmark   July 14, 2007 at 1:23AM
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Here is a photo of a classic nitrogen deficiency in a field crop. It's wheat and doesn't need as much nitrogen as corn but the idea is the same. The lighter green area had only leaves applied late in the fall and then seeded early in the spring. The darker area had a mixture of leaves and grass. Some modifications of the spreading is planned for this year. Live and learn I guess.


Here is a link that might be useful: Nitrogen deficiency visible.

    Bookmark   July 14, 2007 at 8:12AM
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Hi Westy,

I haven't had much botany, but I am a microbiologist so I understand a little about crops from the microbe end of things.

Apologies in advance for stating what you may already know:

Legumes fix their own nitrogen because certain bacteria "infect" the roots of the legumes. These bacteria (several different genera, such as Bradyrhizobium and others) live in symbiotic association with the plants. The bacteria grow within the roots, forming nodules, and they convert N2 (which is 70% of our atmosphere) into ammonia. Some of this goes to the plant.

Non-legume plants do not host these sorts of bacteria, and so they need nitrogen to be directly available in the soil (ie not N2 from the atmosphere.)

Everything you are doing sounds great. As far as pee - in my experience it heats up compost in nothing flat. The main problem with it is that it can easily cause offensive odors - which are quite recognizable as urine - related. So, yes, it will speed decomposition of woodchips, but I would dilute it and use it sparingly. Too much enthusiasm may result in a stench. :) I believe that the problem with animal pee is that it is fully concentrated in one spot of the yard. I am sure others will come along to enlighten us further; all I know is that it heats up a cold compost pile very quickly, and it has lots of nitrogen, so yes - it is a green that will speed your wood chip decomposition.

Marriage is funny - Yours sounds like the reverse of "Green Acres." :) Remember in the opening credits how the farmer tried to grow corn in pots on his wife's balcony, and he was measuring the distance between the pots? Too funny. I hope your hubby is supportive in his way. :)

Finally, I looked on the community garden forum. I don't know where you are in Northern Illinois, but there is a community garden in Skokie.

You could ask around for more options. I used to garden at a comm garden in Madison, so I think many of the cities in the midwest might have one.....??

    Bookmark   July 14, 2007 at 10:57AM
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westy1941(Boulder County, CO)

Patty - you are soooo helpful - thank you for all the info!
And for the link. Madison is a lot like here - I'm actually only 10 miles south of the Wisconsin border - over 50 miles NW of Chicago and yes, Skokie is a hike but I do believe we have community gardens around here in the far-out 'burbs.

So cool that you are a microbiologist! If I could go back and start over I'd do something like that. All of a sudden I am fascinated by science - a subject I hated in college.
You make it easy to understand and I really appreciate this. I'm copying it to a folder.

And I will be busy diluting pee - can't wait to see if there is a reaction (from people!)


    Bookmark   July 15, 2007 at 12:20AM
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