Building Soil with Ramial Wood Chips

JAG
By JAG on Thu, Jun 28, 2012 - 10:09am

I wanted to follow up my comments on using wood chips in the Back To Eden post with a dedicated thread on the subject. I dug up some links that I ran across several years ago to share with anyone interested in this topic.

Most of the research in this area was done at universities outside the US in the 1980's, and focused on using wood chips to create a soil with a high humus content. Specifically, the researchers were looking to incorporate the long-lived (stable) humus found in forest floors into common agricultural.

In the study published by Céline Caron, Gilles Lemieux and Lionel Lachance at Laval University, they cited the following benefits of this approach:

 

  • Better soil conservation due to the water retention capacity of humus content (up to 20 times its weight) and the capacity of water accumulation and management by soil organisms;
  • An increase in pH from 0.4 to 1.2 or, under tropical conditions, in alkaline soils, a decrease in the range of 2.0.;
  • A yield increase up to 1000% for tomatoes in Sénégal, and 300% on strawberries in Québec;
  • A 400% increase in dry matter for corn in both Côte d'Ivoire (Africa) and the Dominican Republic (Carribeans);
  • A noticeable increase in frost and drought resistance;
  • More developed and highly-mycorrhized root systems;
  • Fewer and less diversified weeds; A decrease or complete elimination of pests (under tropical conditions, a complete control of root nematodes, the worst and most costly pest in vegetable garden growing);
  • Enhanced flavor in fruit production;
  • Higher dry matter, phosphorus, potassium and magnesium content in potato tubers;
  • A soil turning from pale to deep brown in the same season;
  • Selective natural germination of tree seeds;
  • A thick moder turning into a soft mull under a sugar maple canopy.

While most people prefer to just mulch with wood chips, I try to compost them first and then use them a growing medium. With such a high C:N ratio, wood chips need a great deal of nitrogen to decompose into usable soil. I typically spray the pile with a high-nitrogen liquid fertilizer (via a hose sprayer) to speed the process. I also bag grass clipings to work into the pile. This year I've been collecting seaweed to add to the mix, burying it deep in the pile because it tends to stink for a while. I hope the seaweed is worth it because its a pain to collect, rinse, and incorporate.

I think the ultimate "supplement" to speed the composting of wood chips will be sludge collected from the mechanical filters of an Aquaponics tank or Koi pond. I can't wait to try this out in the future. I suspect chickens could process the wood chips rather quickly to.

Here is an article by Tom Roberts of Snakeroot Organic Farms In Praise of Ramial Wood Chips.

 

Ramial chips are those from trees and brush, from branches up to about 4 inches in diameter with or without leaves. A fairly high percentage of their mass is thin young bark, young wood, and sometimes leaves.

I think of ramial chips as falling into three categories based on how to use them: summer chips (with leaves), spring, fall and winter chips (without leaves), and evergreen chips (with needles). And within these three categories there are sub-categories, such as cedar chips (long-lasting, poor composters), or alder chips (fast rotting, good mulch), and so on. Ramial chips are what I use most, so I will from here on just refer to them as "chips".

And finally, here is a great article about using Wood Chips in Vegetable Production by Brian Caldwell.

 

From 1951-1965, a remarkable experiment was carried out on a Soil Conservation Service research farm in Marcellus, NY. The project is written up in a 1971 Cornell bulletin called, “Soil Management for Vegetable Production on Honeoye Soil with Special Reference to the Use of Hardwood Chips” by G. R. Free. This 15-year study used a 5-year vegetable rotation of sweet corn, beans, tomatoes, cabbage, and peas. It compared 14 different treatments, including several in which 10 tons per acre moist weight (7 tons dry weight) of wood chips were added each year. Other treatments looked at using overwintered ryegrass or bromegrass cover crops, and more extensive rotations in which legume sod hay crops were substituted for the beans and tomatoes. The hay crops were harvested and removed, not simply plowed under. Crops were fertilized with chemical fertilizers and (as seems likely) probably sprayed for pests and weeds. Crops were also cultivated for weed control.

Some results were apparent within a few years and continued for the duration of the project. Yields of most crops were improved with the addition of wood chips and best when the chips were topdressed on the soil surface after the crops were planted instead of being plowed under. Over the years, soil organic matter (SOM) and nitrogen increased in the chip-amended plots, while they dropped in the chipless plots without cover crops. Including yearly grass cover crops allowed SOM and soil nitrogen to stay at about an even level over the 15 years. 

Anyone else out there care to share their experiences with this approach?

Thanks, Jeff

8 Comments

tictac1's picture
tictac1
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WOW, thank you for posting

WOW, thank you for posting this.  I'm about to re-make half an acre, permaculture-style, and I've been pondering incorporating wood chips into the plan, to make some hugelkulture-style berms.  I have a neighbor with huge piles of euc chips, which have decomposed for about a year, and are chock full of fungi.  Now I've got some instructions for how to do it!

Doug's picture
Doug
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JAG good topic

I'm interested in this topic as I have lots of woods and a firewood operation that produces lots of bark and some chips. I'm wondering if I reduced all of that down to chip size and, as suggested in the Caldwell article, spread new chips and bark on the garden after planting, would I turn it under the following year or do no-till planting? I assume the chips would compost much faster if turned under. Also, how about adding fall leaves to the mix?

Thanks JAG

Doug

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JAG
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Bark Chips

Hi Doug,

If it's mainly bark chips that you are producing, I would compost them for a year before adding them to the garden beds. If you just till them in they will immobilize nitrogen in your beds for 1-2 years as they are slow to break down. 

Believe it or not, Miracle-Gro works great for composting wood chips. Although I don't use it in my garden, it works great as a fast-acting source of nitrogen for the wood chip pile. Be warned though, as it can heat up a pile to really high temps.

Jean Pain is famous for harvesting the heat from composting wood chip piles:

Jean Pain's son talks about his method:

Best...Jeff

P.S.: I typically make leaf-mold out of the fall leaves that I collect, but I don't see why you couldn't incorporate them into the mix if you add enough nitrogen.

JAG's picture
JAG
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Nitrogen Immobilization and Wood Chips

Here is study done to access the amount of N-tie up by pecan wood chips being incorporated into soil: Nutrient Availabilty in Soil Amended with Pecan Wood Chips

 

Abstract

Pecan [Carya illinoinensis (Wangenh.) K. Koch] pruning wood is usually burned, a practice that creates serious environmental concerns. Chipping and soil incorporation of prunings may be an alternative disposal method if nutrient immobilization is not a problem. Our objective was to determine if incorporation of pecan wood chips into soil would affect the availability of nitrogen (N), phosphorus (P), and potassium (K). Pecan wood chips were incorporated into a silty clay soil at rates of 0, 4484, 8968, 13,452, and 17,936 kg·ha−1 in May or June 2002, 2003, and 2004. Some plots received N (ammonium sulfate) at a rate of 0, 15.2, 30.5, 45.7, and 61.0 kg·ha−1 to adjust the C:N ratio of trimmings to 30:1. Wood chip incorporation did not significantly decrease inorganic N regardless of application rate or number of applications. When ammonium sulfate was added to balance the C:N ratio, soil inorganic N increased with the rate of wood chip application, also indicating that N immobilization did not occur. Soil-available P and K were not significantly affected after one, two, or three wood chip applications. Soil-available K increased when ammonium sulfate was added to balance the C:N ratio. Soil incorporation of pecan wood chips does not appear to immobilize N, P, or K, thus providing growers with an environmentally viable means of wood disposal.

(emphasis mine)

Maybe you can dig in your bark chips Doug

Best...Jeff

Doug's picture
Doug
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Thanks JAG

Watching the videos generates a lot of possibilities.  I know some of the guys on the local road crews who generate tons of wood chips every year clearing roadsides and are always looking for places to dump them.   It occurs to me that making a mixture of chips and fall leaves could compost both quickly and turn into good soil additive by the following spring.  A neighbor has a mulching mower and a box that he pulls behind his mower to collect leaves in the fall.  He used to pile some on my property that would generate a lot of heat.  The box actually caught on fire once when he left if full of leaves for a while.  As far as generating usable heat, that's a more labor intensive process and requires some infrastructure that I would have to thing about for a while.  For the time being, building soil is my biggest priority.

Bark and wood chips make up most of what is now the walking surface of my woodshed and surrounding area.  I could probably dig up a lot of well composted material.  Thanks for the idea.

Doug

ferralhen's picture
ferralhen
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i try to mimic nature...top

i try to mimic nature...top down, and years to compost/breakdown. i'm to old and tired to mess with turning piles and rushing nature. i work with nature as it is and i mimic it in places i want composted.

i trade deer hunting on my property with a guy who cuts trees down for the utility company...each year he hunts and i get 30-60 cu yards of wood chips...i specify no black walnut.i also ask for the twiggy/leafy stuff (that no one wants because it's not pretty) because it has a good green/brown ratio.. it takes about 4 years to break down as is dumped and i've done it long enought now to have a natural rotation in place...

in fact, i have enough garden space that i dump on one space and use another for 4 years while the leaves and wood chips and grass clipping break down. then i switch and grow there. that way the good stuff leaches down into the dirt i am going to use. and i don't have to haul it all over the place....it's dumped in place from the start.

i had over 100cu yards of leaves dumped in place from a guy who collects leaves in town. i dump ashes from my wood stove to the mix , egg shells, and rock phosphate.all this attracts birds who eat the bugs and worms and all in all it seems to be working for me in michigan.

while i have a scientific mind, i don't have the disposition to measure and fuss. i know the concepts, and if the plants are productive(which they are) i don't fuss over numbers.

local farmers are curious fellows and they marvel at the 35lb watermelons i give them at the end of the summer. they think i am doing some secret even tho i tell them exactly what i am doing.

they just don't want to believe it's all this simple.

fh

JAG's picture
JAG
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Thanks for sharing your

Thanks for sharing your experiences FH.

I like your patient approach of letting nature do it's thing. I'm sure slow composting in place does wonders for the soil underneath. Here on the Texas Gulf Coast, it only takes about 2-3 years for untended piles to break down, but I just can't help but to tinker with them.

The new pile that got delivered yesterday is already at 106°F just a few inches under the surface (ambient temp 88°F). 

Thanks again for sharing....Jeff

ferralhen's picture
ferralhen
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Posts: 151
hi jeff, thanks for your

hi jeff,

thanks for your sharing and also the sharing of others . i have tinkered too in the past.(so i understand your fascination with it)..i use to take year old wood chips, fresh grass clipping and leaves and blend them all thru my chipper/shreader. it makes a course black sawdust and breaks down rapidly and ready to go in a couple of weeks.(mostly because of it's small size and larger surface area.) it was the

most beautiful stuff, but alot of work to do on a large scale

i also thought it worth noting, i set my yard up for big trucks, so that they could drive in,, dump and loop on out without any extra manuvering.not everyone with a big truck knows how to drive them, and they can tear up the ground pretty quick and make more work for me, i now have a well compacted truck  loop. some of these truck weigh 10-40 tonnes.

i envy your longer growing season, but with hoops and a greenhouse i garden 10 months out of the year , resting in dec and jan.

all the best

fh

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