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hungryfarmer

dig in cedar mulch?

last month

In my very hot and long summers, the compost I dig in at the beginning of the season degrades away, leaving the soil hard and impermeable by the end of the long growing season. I'd like an amendment that keeps the soil loose and permeable for a long time. I could dig in loads of perlite or vermiculite, but that's expensive. Another possibility is to dig in wood chips, that will hang around for a while. Cedar mulch seemed like a good idea because cedar takes years to break down in the soil. BUT, I am warned against digging in cedar mulch because it allegedly robs nitrogen from the soil. That doesn't make a lot of sense, because if cedar degrades slowly, it won't pull nitrogen out of the soil very fast. Can anyone rationalize this? True that cedar shouldn't add a lot of nutrients to the soil, because it doesn't compost fast, but nutrients are not the problem here.

Comments (12)

  • last month
    last modified: last month

    If you dig it in, it is no longer mulch but rather a soil amendment. And yes, if incorporated into the soil, it will tie up significant nitrogen till fully decomposed. And cedar mulch tends also to be more harmful to young plants as it contains volatile oils and terpenes that affect plant growth.

    Avoid digging in where you intend to plant seeds or young seedlings. It is less likely to affect more well-rooted plants and the nitrogen tie-up is more easily offset.

  • last month
    last modified: last month

    OK, let's try this again. Cedar decomposes very slowly. As a result it will not tie up nitrogen very effectively. If it just sits there, it isn't tying up nitrogen. Other uncomposted wood chips certainly would. Nitrogen isn't an issue, as I regularly amend with ammonium sulfate. Also, as I said, compost decomposes too rapidly. I do amend with compost regularly, but it's no longer contributing to the friability of the soil at the end of the long growing season. Yes, that's true that fresh cedar can be allelotropic, but the stuff I'm looking at must be well aged because there is little or no smell. Thujone is the allelotropic ingredient that makes the cedar smell.

  • last month

    No. I would not dig in wood chips of any kind. You need a lot more, leaves, straw, etc. Also plant those Daikon(sp) radishes that break up the soul over the winter.

  • last month

    I already dig in lots of composted leaves, and I mulch the surface with straw. That does not keep the soil friable at the end of a very long growing season. That's a fact. You obviously can't dig in more as the season progresses, because there are plants already growing there. Putting in a lot more at the beginning of the season doesn't really make it last longer. There is just more degradation going on. I've tried that. Also, this is not about breaking up the soil in the winter. Before the summer season starts I dig the beds deeply. This is about keeping the beds friable by the end of the growing season. This is very much a southern gardening issue, because we're talking about a summer growing season that lasts almost 9 months.

  • last month
    last modified: last month

    I live on the south! If you do not want our experience, just do what you want and learn the hard way.

  • last month

    I'm just asking for clarification of online advice that makes some sense. What I see online about cedar eating nitrogen rapidly just doesn't make a lot of sense. I'll try amending one bed with it and see how it works. Thanks for your time.

  • last month

    Cedar decomposes very slowly. As a result it will not tie up nitrogen very effectively.

    This is simply incorrect. ANY wood mulch, when incorporated into the soil, will tie up nitrogen. It has very little to do wiith the rate of decomposition but just the fact of wood requiring nitrogen to decompose. At all. Period.



  • last month
    last modified: last month

    The fact that all wood requires nitrogen to decompose is my point. You agree with that. Cedar decomposes slowly. Thereby it has to use nitrogen more slowly. I understand that cedar can take several years to decompose. Other wood mulch can do so in a year. I could accept that cedar ties up nitrogen effectively in the soil IF someone can state persuasively how it manages to do that while it is decomposing slowly. I can agree that it ties up some nitrogen, but not as fast as other wood might. Cedar is not "any wood".

    Nitrogen is not a nutrient issue for my beds because, as I say, I apply nitrogen fertilizer regularly. Soil friability is a big issue for me. So there is a tradeoff that I'm making.

  • last month

    I'd just do as you suggested above and experiment in a bed or two and judge for yourself.

    A few years ago my brother brought in a truckload of pine mulch in the fall and tilled it into his huge sandy loam garden and he had a horrible yield the next summer. He didn't tell me about it until after the fact or I would have warned against it. He is in Wisconsin so the ground was frozen for much of the time so not apples to apples with your scenario in the south.

    Good luck and I hope you find a solution to your problem.

  • last month
    last modified: last month

    That's sensible. Pine mulch will decay in a single year, and suck all the nitrogen out in that year. Cedar can last four years underground, so it will pull nitrogen only a quarter as fast. No question that uncomposted material pulls nitrogen out of the soil, but what's important here is how fast that happens. Yes, I have 2 cubic feet dug into a 5x5 bed that I use for collards. As a green, they need nitrogen! But I think I dug in a pile of uncomposted leaves in that bed last year, and had no problems this summer.

  • last month

    hungryfarmer, you need to talk to daninthedirt, he had the same problem and similar question. Also ask klem1 and Kevin (outpatientzero spelled wrong), they are also soil experts just like daninthedirt. All seem like your brothers from different mothers!

    Good thing garden"gal" is here to help you, she is such an expert, her spidey sense must have been tingling.


    Good luck.