Recovering from the classic wood chip fiasco - some practical questions

Hi folks - like a lot of other people who have to start from scratch with limited/no access to logs, I used wood chips last year to begin my first try at raised bed Hugelkultur.

It's all clear in retrospect that my really crummy growing season was nearly entirely related to nitrogen sequestration by the wood chips, so I'm hoping I can address this in the coming year.
I live in the Pacific Northwest in an 8b zone, so I'm looking at getting my transplants and seed starts into the beds in probably 10 or 11 weeks.  This will depend a bit on how much moderation of temps we get from El Niño this spring.

I have five 30 inch raised beds of varying sizes, each filled about 50% on the bottom with wood chips.  I think that the wood chips are predominantly local fir and pine and I do not have any reason to suspect any allelopathic wood content.

So, the questions I am hoping to get help on are as follows:
1.  How much ongoing nitrogen sequestration should I expect this year?
2.  Would adding mycorrhizal amendments to the soil help accelerate the wood chip breakdown?
3.  I have access to some OMRI-certified 13-0-0 fertilizer, which takes around 8 to 10 weeks to break down.  I'm thinking of adding this to the beds more or less immediately and probably again after my transplants are settled in, some time in May.  Does this seem reasonable?
4.  Should I consider any more immediate amendment interventions like adding manure?
5.  Any additional suggestions or comments?
Many thanks!

How did you plant up your woodchip bed?
Direct seeded or transplants?
Did you amend - compost, comfrey, seaweed, animal manure?
Have you considered inoculating with edible fungi - wine caps, rugosoannulata etc?
What crops did you plant?
Heading to bed now but try searching for Eric Hanson's excellent thread about woodchips to start new garden beds. He had excellent results with his tomatoes.

Megan has asked some very good questions. Was your hugelkultur just dirt and wood chips?

My suggestion would be to start adding more organic material as a top dressing.  Leaves, leaf mold, compost, and mushrooms.

Rather than an organic fertilizer maybe use compost tea.

Why do you feel the problem was nitrogen sequestration?

I am looking forward to what others suggest.

Yep, I've done it too...

1.  How much ongoing nitrogen sequestration should I expect this year?

Nowhere near as much. I made wood chip beds and they were just like you described the first year. The second was "ok" and then they are off to races since.

2.  Would adding mycorrhizal amendments to the soil help accelerate the wood chip breakdown?

Definitely.

3.  I have access to some OMRI-certified 13-0-0 fertilizer, which takes around 8 to 10 weeks to break down.  I'm thinking of adding this to the beds more or less immediately and probably again after my transplants are settled in, some time in May.  Does this seem reasonable?

I would put it in now but personally not later when you are growing. That's mostly because 13 Ns seems pretty hot to me.

4.  Should I consider any more immediate amendment interventions like adding manure?

Yes. If you could mix in some chicken manure or duck water you would be in a good place. Same with the 13-0-0, give it plenty of time to "cool".

5.  Any additional suggestions or comments?

You can game the system by planting your plants in fertile holes of good soil within the beds . Say 6x6x6 inches. That will help them, especially when they are young. And then by next year it shouldn't be necessary.

Compost tea is what lets my garden grow in bad soil. I usually hit it right after transplanting and sowing and then about halfway through the season.

I would be dollars to donuts that if you do what your leaning towards you will have success. Especially since donuts cost more than a dollar now! And they are delicious.

My reading strongly suggests that the big issue with wood chips is that lignin is difficult to break down. From an article:

microorganisms have evolved different enzymatic and non-enzymatic strategies to utilize this plentiful plant material

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812493/
This supports my experience, and makes me agree with the suggestions above about asking mushrooms to help.

I have *not* seen any benefit from adding nitrogen (my source is urine) if there aren't plants growing in the wood-chips. I want the micro-organisms to be eating the lignin, not sucking up the nitrogen.

If my plants are struggling in a wood-chip environment, I think I'd be inclined to try the compost tea and water +/- diluted urine near the plants, but that's just from my observation in my ecosystem.

Hi Russell,

Life has taken me away for a couple of days so while I have been following this thread I have not had a chance to respond till now (5 days late!  Sorry.)

My thinking is pretty much in line with what others have already said.  I would try to get as much plant life growing in those beds as possible--which is what you already tried to do, but maybe we can try a couple of different approaches.

Approach #1.  When I plant my tomatoes in a newly made bed filled with fresh wood chips, I always cheat just a little and I actually plant the tomato plants in fertile holes about 12" in diameter and 6-8" deep.  Those holes are backfilled with either bagged manure (the only type I have easy access to)  or some topsoil.  Either way, giving some organic fertilizer is not a bad idea--I like to use Blood meal as I think it lasts a pretty long time.  It is only natural to think that my tomato plants will become root bound in a sort of manner, but actually the roots grow well outside of the fertile hole, meaning that there must be some type of life out in those chips for root interaction.

Approach #2.  I would still use the fertile holes, but maybe try to include some chunks of topsoil about the size of your fist throughout the chips.  The point is to make little reservoirs of healthy soil microbia that can then spread into the chips.

Approach #3  You can still do all of the above, but maybe consider planting large numbers of legumes like peas or beans.  If inoculated, these plants will fix their own nitrogen, and as they grow, their roots will spread into the chips and continue spreading soil microbes.

Approach #4.  Of course, you could try to use fungi/mushrooms.  Wine Caps are amazing, but maybe also consider something local to your region.  Either could be a winner.

Approach #5.  If you have it, consider mixing high quality compost with half of that topsoil in the fertile holes.  Also, if growing peas/beans, consider growing them in fertile trenches.  Again, compost can be amazing if you have it.


So there you have 5 different approaches that are all to some degree compatible with each other.  Feel free to mix & mash them together or make changes of your own.

Good luck and please keep us informed as to your progress.

Eric

Wow folks!  Thanks for all the replies!  Much appreciated.  
Sorry for the late response - I've been recovering from some surgery.
I'm going to try one post here to respond to all of your helpful comments and questions.
I apologize in advance for its length.
I should probably go into more detail regarding how I constructed my beds.
We had just moved to the area in a newly constructed house, with no local gardening support system.  1 or 2 local nurseries not offering their own composting and big box stores were my materiel sources.  There appears to be a real dearth of locally source-able organic mulch and compost.
They are raised beds, using the Vego system for containment, 30 inch height. I used a fairly "classic" layered material approach.
Bottom of beds lined with brown cardboard, avoiding colored/dyed sources.  Filled to approx 50% with local, bulk wood chips, mostly pine/fir (I live in Washington state).
Next layer is bagged, "big-box" mulch, about 4-6 inch depth, used for budgetary reasons.
The remainder of the depth was a combination of about 50% bulk local topsoil, 40-45% bagged compost and bagged cow manure.
I used a combination of direct sowing and transplants.  Pretty much everything I sowed would germinate and then after about a week or so, growth would stall.  Some seedlings like cilantro and oregano would show yellowing.  Others, like beets and carrots would just not grow much beyond 1 or 2 inches in height.  Tomato transplants limped along with low yields.  Pole beans grew, but were sub-par in height obtained and in production.  Onion and garlic sets barely grew.  Lots of leaf yellowing and slow growth of squashes, in spite of very good luck with pests and powdery mildew.  I doubt I got more than 2 or 3 zucchini and yellow squashes the whole season.  Transplants of sage, rosemary and garlic chives barely grew.  Some co-planting of marigolds also grew very slowly and poorly.
Obviously, the beds settled several inches since construction. I will need to bring them back up to full depth with amendments soon.  Probably will use a combination of 50% topsoil, 30% good quality organic bagged compost and the balance as potting soil.  Seriously considering biting the bullet and using G&B organics products for these sources.
There certainly seems to be a wealth of possible fungal inoculations I could choose from.  The question in my mind is how to add them.  I want to do minimal tilling, so it seems there are two possible ways to go:  (1)  Combine the mycorrhizal source with my top dressing for this season or (2) bore holes down to the wood chip layer from the top and get the fungi down to the interface.  That would obviously be more work.
Going forward during the season, I'm also planning to use a kelp supplement regularly, both as a tea and direct foliar spraying.
Thanks again, everyone!

Russell,

If I had read your post more closely I would have realized that your predicament was different that what I imagined.  I was thinking about placing wood chips on top of soil, but you did exactly the opposite.  So with that in mind, I am going to review what I think you have.

1.  you have a 30" tall bed that is now settling a bit.
2.  16ish inches were filled with local wood chips
3.  5ish inches were filled with big-box mulch
4.  The next 9 inches were filled with a combination of bagged topsoil and bagged manure

Does all of this sound about right?


If this is about right, I might have a different answer than what I suggested in my earlier post.  Actually, I am wondering about how well-watered the plants were.  The reason I ask is that soil sitting on top of a whole lot of chips and mulch will--before decomposition--act much like gravel in a French drain and simply drain away water easily.  Did your plants show any signs of water stress?  Did you water frequently (meaning daily)?  

The other thought I had was that perhaps they roots were getting started and then outgrew their topsoil layer.  If the roots got into the wood chip zone prior to significant decomposition and without any soil, they might not have had many nutrients to gather (including water).  If this is the case then they would indeed look stunted.  9 inches of topsoil is really not a lot of soil for a plant to live in and whenever I dig into my plants at the end of a season, I find that my roots go VERY deep, even for things like peas.

With all of that in mind, I am thinking about ways to get soil and decomposition into the wood chips below the soil.  My thought is for you to dig those holes and really bore into the wood chips and maybe take the combination of wood chips and top soil/manure and mix them all together and put them back into the hole.  Maybe consider amending that wood chip/soil mixture with blood meal, bone-and-blood meal, kelp meal, etc. just as long as you can get some nutrients into the deeper layers of the wood chips to encourage root growth into those zones.  Root growth will really help promote further decomposition.

BTW, using the organic fertilizer is perfectly legit in this stage as you need something to get the initial burst of plant growth going.  But continuance of fertilizer will tend to break the relationship between fungi & bacteria and plant roots.  So I am certainly not saying don't do it, just consider what repeat applications tend to do.  Once you get the biology going in all those wood chips, will provide you with all the nutrients you will ever need.

Also, maybe consider growing something that will grow a really deep root to help mix the layers together a bit and also further promote decomposition at the deeper levels of the wood chips.

Hopefully all of this will make sense and better yet, be helpful.

Please let us know how things work out.

Eric

Thanks for the thoughtful reply, Eric!

The top half of my bed composition was a mix of about 5-10% manure and then equal parts of topsoil and compost.
Your point about drainage was a good one, but I was very conscientious about watering and monitoring soil moisture.  I checked water status with an actual probe, so I'm thinking that water stress was maybe not a major problem.
It's encouraging that we seem to be thinking along similar lines about boring down to the chip layer and "innoculating" the bottom of those holes.  I'm getting a line on a hand augur and bit I might use for that.  I'm loathe to dig much bigger than that, as I'd like to keep my overall bed interventions tilted towards more of a no-till approach.  Even though I may not have much of a mycelial network at this point in time,  I'm keen not to disrupt my early microbiome evolution any more than needed.
If I can get the auguring done soon,  I am leaning towards throwing down my 13-0-0 and then simply topping the beds off with a good quality, organic raised bed/potting soil mix, perhaps something from G&B.
In my mind, that would provide a decent substrate for germination and early growth and when the roots get down past 3 or 4 inches, they'll be at the interface where I put the 13-0-0.
You raise a good point regarding ongoing exogenous fertilizer.  My inclination right now is to go kelp-based for any further nutrient additions as the season progresses.
Thanks again!

Russell Whittemore wrote:

The remainder of the depth was a combination of about 50% bulk local topsoil, 40-45% bagged compost and bagged cow manure.
I used a combination of direct sowing and transplants.  Pretty much everything I sowed would germinate and then after about a week or so, growth would stall.

It looked like the seedlings just started used up reserved energy from the seeds but couldn't get nutrients through the roots. This had nothing to do with the bottom wood chips or mulch layers since the roots would be only inches deep. I highly suspect the bagged supplies are inhibiting plant growth as I had bad experience with purchased stuffs before.

There's still weeks before the growing season starts, so if you feel like testing the growing mix it can be done easily indoors. Buy a bag of high quality potting mix such as Promix or Mel's mix, or homemade compost etc and use them as control. Fill a cup with the soil mix from your raised bed too and plant garlic cloves, radish seeds or beans. These will grow very fast to see the results in a couple weeks. See how it comes out and go from there.

Thanks for replying, May!
I think your suggestion is pretty reasonable and it addresses another possible variable.  I will see if I can get some things to grown with samples from the beds as they currently are.