Fact or fiction?

True, with a caveat or two: Any material absorbes nitrogen as it decomposes. If it doesn't contain much nitrogen of its own, the deficit comes from its surroundings. Having said that, if the wood chips or whatever are on the surface, they won't steal much N from the soil under them. And if the "brown" material is partially rotted already, there's less of an issue. So, let it rot and weather as mulch before turning it in, or partially compost first, and you'll be fine.

Gary Woods AKA K2AHC- PGP key on request, or at home.earthlink.net/~garygarlic Zone 5/6 in upstate New York, 1420' elevation. NY WO G

Reply to
Gary Woods
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I seem to remember that wood as it decomposes uses up the nitrogen in the soil. Not really good for the garden. Old wives tale or true?

Reply to
The Cook

In terms of both its physical and chemical properties, wood is an exceptionally difficult substrate to degrade. One of the principal reasons is that wood contains very low levels of nitrogen, which is needed to produce the enzymes that degrade the main structural polmers of wood - cellulose (about 40-50% of the dry weight of wood), hemicelluloses (25-40%) and lignin (20-35%).

The lignin component also presents a barrier to wood decay because lignin is a complex aromatic polymer that encrusts the cell walls, preventing access of enzymes to the more easily degradable cellulose and hemicelluloses. In addition to these points, wood often contains potentially fungitoxic compounds, which are deposited in the heartwood. In broad-leaved trees the toxic compounds are usually tannins, well know for their ability to cross-link proteins, making animal skins resistant to decay. In contrast, conifers contain a range of phenolic compounds such as terpenes, stilbenes, flavonoids and tropolones. The most toxic of the tropolones are the thujaplicins which act as uncouplers of oxidative phosphorylation; they are particularly abundant in cedarwood, making this a naturally decay-resistant wood for high-quality garden furnishings, etc.

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When the nitrogen is no longer needed for enzymes or fungal growth, it is released back into the soil environment for use by other microbes, and plants.

Reply to
Billy

I think of rotting as burning. Everything burns up some faster than others. Rusting is oxidation aka a slow burn.

A book that touches on this as a side issue is "Arctic Dreams " which notes the slow decay in arctic areas. Dead animals and foot prints about for years. Many stars and due for a reread.

Reply to
Bill who putters

A better way of describing it would be being eaten rather than burnt. Burning doesn't involve nitrogen whereas the microbes that decompose wood do use up nitrogen as well as oxygen.

Gary had it pretty well right. Nitrogen is used up to some extent but it may not be an issue and it gets returned later. The situation has to be fairly extreme for nitrogen draw down to severely deplete the soil. This can be used to your advantage by using sawdust on paths, little or nothing will grow in it for a year or two.

David

Reply to
David Hare-Scott

So I have a follow up question to that very interesting question! Is it Ok to BURY freshly cut wood, logs and chips, under the vegetable garden soil? Your opinions do count. Lots of great advice here.

I have this book, "Gaia's Garden, Second Edition: A Guide To Home-Scale Permaculture by Toby Hemenway" ISBN-10: 1603580298. On page 84, "Woody Ways to build soil" Its called "Hugelkultur". That freshly cut wood can be instantly used in vegetable gardens. The buried slowly rotting wood feeds the plants and improves the soil.

One link about this:

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am not sure if this is sound advice or not.

Reply to
Dan L.

I've found a few glitches in Gaia's Garden, like using a circular sprinkler to water a keyhole bed containing tomatoes, to name one. For immediate use, it sounds as if the web site is advocating adding green material (fall leaves, grass clippings) to the wood (log, limbs, twigs) which will contain some nitrogen. They also advocate manure in place of the green material. The book talks of using grass as well, but also suggest straw, and sod (from sod I know nothing). Brown materials won't contain nitrogen, but according to Gaia's Garden the hugelkulture releases heat and moisture which encourages growth. If I were doing this, I would use manure with the wood and, at a minimum, the equivalent of 18 lbs of chicken manure/ 100 sq. ft.. Manure Chicken Diary cow Horse Steer Rabbit Sheep N 1.1 .257 .70 .70 2.4 .70 P .80 .15 .30 .30 1.4 .30 K .50 .25 .60 .40 .60 .90

As I mentioned to "The Cook" earlier,"In terms of both its physical and chemical properties, wood is an exceptionally difficult substrate to degrade. One of the principal reasons is that wood contains very low levels of nitrogen, which is needed to produce the enzymes that degrade the main structural polmers of wood - cellulose (about 40-50% of the dry weight of wood), hemicelluloses (25-40%) and lignin (20-35%)."

Here we have contradictory statements for Hugelkultur (green and brown amendments). We are told that composting wood is good for heat and humidity. We know that fungi need nitrogen to break down the wood. I would stay away from adding more brown material to the wood.

Otherwise, it sounds OK for potatoes, berries, and melons, but squash require high inputs of nitrogen. If growing squash, I would add organic fish emulsion twice a month, until flowering (then no further nitrogen), to insure nitrogen levels are sufficient.

Reply to
Billy

Now that name is a blast from the past. He used to post in the alt.permaculture newsgroup many moons ago.

Reply to
FarmI

Actually my husband and I were discussing the cedar chips versus grass clippings as mulch for the rhubarb. He is thinking that the cedar would be there for a long time. I am thinking that the chips cost money and would get moved into the other parts of the garden. Grass clippings a free and do provide some nutrients for the plants as well as helping to keep the weeds down. We do have about an acre of grass that needs to be mowed regularly.

Reply to
The Cook

19th century market gardeners near Paris used a very similar technique. Adding enough manure or green material to the wood created a hot compost pile underneath the soil. This allowed earlier planting and much higher prices for the early veggies. Steve
Reply to
Steve Peek

Cedar chips would be the opposite of grass clippings as a mulch. Are we talking mulch as a ground cover, or mulch as a nutrient? Cedar chips breakdown slowly, making them a good ground cover, but a poor nutrient. Grass clipping break down quickly, making them a quick nutrient source for soil microbes.

Reply to
Billy

The book is interesting. I like the garden design ideas. Garden techniques I am not so sure. I am not sure if Amazon.com is a curse or blessing :) More in common than shoes :)

Sounds like this could be a good way to jump start a garden in cold Michigan. I would just need a row cover on those late frost dates. Chemistry and Biology was not on my candy store list. A weakness on my part.

I have lots of grass and chicken poop mixed in with the straw. Hen House thing. So adding Manure with straw to the wood might be a mixed blessing.

I only plant ONE squash plant and thats it, all that is needed.

Reply to
Dan L.

He probably got rich from your postings :)

Reply to
Dan L.

What was old then is now new again :)

Reply to
Dan L.

Right down to putting cloches over the plants. We forgot a lot with the "green revolution".

Reply to
Billy

Compost formula = 2(30 parts brown/1 part green)+ 1(manure)

Ex. 18 lbs (twigs, branches, dried leaves) + 2 lbs (grass clippings, pulled weeds, plant trimmings) + 10 lbs manure (no specific type mentioned). Let it Rot!: The Gardener's Guide to Composting (Third Edition) (Storey's Down-to-Earth Guides) (Paperback) by Stu Campbell

Reply to
Billy

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Reply to
Bill who putters

Compost formula = 2(30 parts brown/1 part green)+ 1(manure)

BIG WHOOPS. Make that

Ex. 30 lbs (twigs, branches, dried leaves) + 1 lbs (grass clippings, pulled weeds, plant trimmings) + 15.5 lbs manure (no specific type mentioned).

Sorry about that :O) Let it Rot!: The Gardener's Guide to Composting (Third Edition) (Storey's Down-to-Earth Guides) (Paperback) by Stu Campbell

Reply to
Billy

Good picture, thanks.

Reply to
Billy

Amazon is definitely a curse. I just have the "The Rodale Book of Composting: Easy Methods for Every Gardener" 1992. An old outdated book, has nothing on handling wood. "Let it Rot!' is on order :)

One headache is Rose Bush trimmings, A real pain in the ... In past I just simply buried them in the ground. I see I should have buried them with other compost materials.

I used to think Roses were cool and part of all nice gardens. Now in my old age I hate the things. I now think there ugly. Not even worth putting in a vase. Years ago I had dozens of them. Now down to four bushes and tempted to rip them out.

Reply to
Dan L.

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