adding nitrogen to hardwood shavings compost?

August 27, 2019

Any advice/info welcomed! I have a source for kiln dried hardwood shavings from a custom furniture builder in town. I picked up 3 lawn/leaf sized bags today that he said was mostly ash, elm, oak, and about 12% walnut today - the mix changes based on his orders. He did say he could keep the walnut separate in the future so I wouldn't have to take it (I don't know if the juglone is primarily within roots, and if it breaks down in compost). He can give me 2 - 3 bags like this a week through December since it's his busy season. My question is if I can speed up the compost process by adding nitrogen to the pile. I want to start a new pile with what I get from this guy, and I wondered if adding alfalfa pellets, blood meal, or urea could be beneficial. If at all possible I'd like to get the process going well enough that I can use a portion of this in the new raised veggie and flower beds I make late next spring. If it would need another year to compost I could do that, too, but I was hoping to be able to use some of it next year. The compost will have more than just the hardwood shavings, but it will make up about 1/2 the pile. Thanks for any info!

Comments (21)

  • tsugajunkie z5 SE WI ♱

    Are they large shavings like from a plane or is it sawdust? If large, I might consider using them as mulch, if dust any N you can add would help a great deal. Juglone breaks down easily in compost, so that should be a non-issue.


    coatfetish thanked tsugajunkie z5 SE WI ♱
  • coatfetish

    Thank you, I didn't know juglone will break down easily, so I can let the guy I'm getting it from know. It's sawdust and tiny, tiny pieces - like cake crumbs (which now just makes me want a piece of cake, lol). Thanks for replying!

  • LoneJack Zn 6a, KC

    If you need to add purchased N inputs then Urea would be the most cost effective. I can get 50 lbs. for $14 at my local Ag coop, Since you are also posting this on the organic forum you might be more inclined to use alfalfa pellets. Can you find any manure for the N input? Anybody have a flock of chickens near you?

    coatfetish thanked LoneJack Zn 6a, KC
  • gardengal48 (PNW Z8/9)

    Probably the most cost effective source of N for the compost is what the OP is able to provide themselves :-) Peeing in the compost.

    coatfetish thanked gardengal48 (PNW Z8/9)
  • toxcrusadr

    ^^ Beat me to it!

    Also makes a great material to cover your kitchen waste additions all winter.

    It's still mowing season so maybe you can score some grass clippings?

    coatfetish thanked toxcrusadr
  • armoured

    I find naturally adding (per gardengal) helps a lot. But even if it didn't I'd probably still do it.)

    coatfetish thanked armoured
  • coatfetish

    Thanks everybody! I actually have 8 hens myself and do the deep litter method, so I clean the coop out twice a year - it's in it's own compost pile since the few droppings in the floor of the coop are already mixed in with the 8" or so of pine chips. 90% of the chicken's droppings land on what's called a poop board under the roost (in my case, I made one out of a horizontal door). I am getting ready to scrape that clean for the winter and will add that to the sawdust pile. I did order some urea online - and peeing on the compost won't happen here - I'm in the 'burbs with no trees or barriers between me and my neighbors, haha! I haven't had any grass clippings in a month - we've been having such a drought with temps in the 90s, my yard looks like straw. These's nothing to mow, sadly. But I love all the ideas and thank you for contributing and giving me things to think about!

  • armoured

    Just a comment on your intended use - as a rough guideline if you're using on top of your beds as a mulch and the piles have aged a bit you will have no problems. If you are digging in or tilling in, they can tie up nitrogen for a while as they decompose. The more they have aged until they resemble soil as much as possible and the proportions to regular soil matter. My own experience is that if the stuff smells earthy and is somewhat dark, the fewer issues. Some plants may need more nitrogen and be more sensitive. But i have been surprised at how readily some plants will grow in even straight sawdust and woidwood chips. Air exposure helps a lot as microbes and fungus colonize and bring their own nitrogen to the party. So, turn the pile from time to time.

    coatfetish thanked armoured
  • armoured

    An additional thought on piles of sawdust / shavings: I find it challenging to get the mix of water / air right. It's very different from wood chips where the chips have enough structure (mostly) to let air in and excess water to run out. With sawdust and shavings, they need a lot of air and water (because the cells internally are dry and dense), and adding much water means the piles settle and can go anaerobic - not as smelly as regular too-wet compost, but won't break down well. The material both sheds water initially but can absorb a fair amount over time. I don't have much of a suggestion except add water more frequently than with regular compost (which with normal 'green' household stuff in my climate means very infrequently), and turn it with a pitchfork often. After a while adding water becomes less of an issue, of course. The other potential way is to mix the partially-decomposed sawdust in with other materials or compost. Lack of air as it compacts is the bigger issue, in my opinion.

    Mind, I'd be happy to have such problems and would mostly take as much sawdust/shavings as I could get. Mostly I'll just spread it around as mulch. Most soil including even lawns can absorb a fair bit from the top; it might be noticeable from colouring for a while but just becomes part of the soil pretty quickly. Note though I'm not growing a lot of veggies or other that demand a lot of nutrients.

    coatfetish thanked armoured
  • NHBabs z4b-5a NH

    We mix it with manure, so your chicken droppings would be great. If you have any other sources of more coarse material to mix in to prevent it going anaerobic, that would be great. You don’t want to only use this composted material to fill raised beds. Plan to mix with regular local soil so there is a mineral component.

    we also use it in small amounts as lawn topdressing, usually along with a small amount of a nitrogen source. It has helped raise the organic percent in our soil to help make it more resilient during drought.

    coatfetish thanked NHBabs z4b-5a NH
  • coatfetish

    Thank you, those are all great points and advice. Yesterday I went out and intermixed the sawdust with the coarser pile of coop shavings and chicken droppings (which has been composting for about 4 months), as well as mixing in a large amount of yard soil I dug up earlier in the summer while digging a 3'x56' bed for a rose hedge. My soil here is largely clay so I had a fair amount of "raw" yard soil left over from where I amended the strip the roses were planted in, and in volume the raw soil was almost equal to the amount of sawdust. So basically my new pile is approx. 1/3 soil, 1/3 coop compost, and 1/3 new sawdust - with a small amount of old grass clippings and kitchen scraps mixed in. I did order urea which should be here tomorrow, and I bought some alfalfa pellets. Just because I'm curious, I'm going to divide the pile and add pellets to one and urea to the other and see what it all looks like late next spring. And I have to buy a pitchfork, lol. Thank you!

  • armoured

    If you are continuing to get more sawdust, you may want to experiment with adding soil to a batch only after it has composted for a couple months with turning or when applying kror digging in. With urea or manure added, there is some chance you will get a hot composting phase that will be faster. Adding soil at the beginning will likely stop the hot phase. No big deal, will just take longer.

    coatfetish thanked armoured
  • kokopellifivea

    I customarily break down wood chips with urea. I suppose it might be well to mix some in to head off the anaerobic scenario mentioned above.

    A pile like that is just a tremendous sink for N. Plan on adding N for months after the initial breakdown. I doubt your chickens will do it by themselves.

    I try to keep the additions aft the initial breakdown in the “biologically plausible “ range. Like 250g of urea a week mixed with several gallons of water.

    coatfetish thanked kokopellifivea
  • toxcrusadr

    Yesterday I found in the dumpster at the local farm supply, an entire pallet worth of heavy bags of deer feed/attractant. Essentially a granular grain product. It was in heavy paper bags that were water stained, but most did not even have wet product. Often their stuff gets wet in an unexpected rainstorm before they can move it inside, so they discard it. 16% Protein so the nitrogen content would be pretty good, and 0.5% P. I harvested half a dozen 30 lb bags but my truck already had a load of topsoil from my country place so it was weighed down. It's a shame, there were at least 20 more bags of great compost ingredients/soil amendment that went into the landfill this morning.

    I wish they would put this stuff out for a dollar a bag, or even free, instead of wasting it. Lawyers. <eyeroll>

    But if you have such a place nearby you might ask the manager if you can take home spoiled products for composting. They might be glad to give it to you. Anything from dog food to chicken, horse and rabbit feed has nutrients and especially nitrogen in it.

  • armoured

    I can no longer keep these threads straight but have a good-sized pile of wood chips (perhaps a cubic meter), with some mulched dried leaves mixed in. Most of the wood was dry with not much else, but there was a good portion that was greener wood/branches with leaves attached (mostly maple so the leaves also had bunches of spinners). I added a modest amount of ammonium nitrate (basically urea but less concentrated), watered thoroughly a couple of times, and occasional buckets of water from the dehumidifer in the basement and some, ahem, let's say "natural diluted urea."

    Today checked the pile with the highly scientific method of sticking my arm in. Good and warm six inches in and tending to hot in the part I could check with a laser thermometer, was about 36C/100F, probably hotter further in (almost uncomfortably warm but not burning hot), slightly damp to the touch but not wet or slimey. Since there's a lot of chipped wood with physical structure, not at all worried about a lack of air in there.

    I'd added some chipped very dry wood waste a week or two ago. This is going to sound like wine descriptions, but that stuff was very dry and had a very strong musky mushroom smell - basically all mushroom; the part of the pile I had my arm in today was perhaps majority mushroom but strong earthy/soil tones. (I would buy a wine with this description)

    Anyway, short form, very happy, it's cooking away and I'll leave it alone until the temperature in the pile goes down, perhaps adding a bucket of water from time to time. Likely turn it a couple of times depending on the weather. Goal is to be able to spread the bulk of the pile just after the last of the (heavy) leaf fall is raked up and mulched for composting / before winter snow cover is established. (The last don't always sequentially follow, weather-wise)

    Anyway for our kitchen waste and regular leaf composting I don't bother even thinking about pile temperatures, they exist mostly to reduce waste/pile size, and it's ready when it's ready (the compost gets empty when it's full or we have someplace to dig it in). Modest wood chip amounts from falling branches etc I just use as a mulch wherever. This year have had a lot of extra wood chips due to tree work, more bare ground to cover/rehabilitate, so very happy this pile is cooking away with minimal work.

  • toxcrusadr

    >>the part of the pile I had my arm in today was perhaps majority mushroom but strong earthy/soil tones. (I would buy a wine with this description)

    But would you stick your arm in it?

  • armoured

    The temp of the pile seemed to have gone down and mostly seemed dry rather than damp. And I had some free time, so I turned the pile, wetted it thoroughly, and doped it with a bit of nitrogen. Heated up again quickly.

    Two things I noticed:

    -wow, piles of wood chips can absorb a lot of water to get anything like thoroughly wet (since in current conditions I'm sure it will return to just damp quickly.

    -no surprises really in turning, save that there were pretty thick white mushroom-stem type formations in many places. I assume these are hyphae, but they were thick - more like the stem thickness of full-grown mushrooms. I've not seen them looking like this before (assuming they are hyphae).

  • HighColdDesert

    By the way, for adding homemade, ahem, diluted urea to a compost pile in a public place such as a suburban yard, a discarded can or opaque container can be very convenient...

  • toxcrusadr

    You can lay a tarp over a pile to reduce evaporation caused by wind and sun. Just don't seal it up completely, allow some air to get in and out.

  • toxcrusadr

    @HighColdDesert Or darkness. I am often out doing late night gardening with my headlamp, when it's cooler, so all I have to do is turn off my light and no one can see a darn thing. :-]

  • armoured

    Thanks. Generally with our climate it's wet enough that I don't need to use a tarp (and don't want to), just it's been unusually dry with no/very little rain for more than a month. That spell seems to have been broken and the occasional bucket of water from dehumidifier should be more than enough for the pile of woodchips. My regular composter for kitchen scraps has a cover I usually leave part open, but what goes in there has a lot more water content i.e. kitchen scraps and the like - for that the cover is partially open to let water evaporate. Note these have partial tree cover and shade/less direct rain.

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