New purchase and a learn

Peter44

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I recently purchased a pretty nice small maple grown from the seed of a Coral Bark Maple from Mendocino Maples down in Ca. Nice tree and he sent along some directions which I actually read. The directions said in part,...."do not use green bark products as amendments Freshly milled bark that has not been composted will slowly rob plants of nitrogen when used as an amendment". Just wondering about this as I buy conifer bonsai soil from BJ's and it has 32% fir in it and I don't think it is composted. Thoughts??
 

Japonicus

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Even IF Jacks Douglas fir bark were "green" and it robbed nutrients as it composts
surely nitrogen is reconstituted as you feed. You do feed your maples right?
Also I'm pretty sure you can buy your own components for less at BJ's than pre made
and you'll have better control as to what amount of X each tree or species gets.
Conifer Blend:
32% 1/4 inch Douglas Fir Bark, 32% 1/4 inch Pumice, 15% 1/4 inch Lava, 15% 1/4 inch Monto Clay (1/4 inch Turface) and 6% 1/4 inch Horticulture Charcoal.
 

Peter44

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I grow way more collected conifers than I do deciduous trees, and yes I fertilize. I sent a note to Jack and we will see what he says. I know a lot of growers use larger composted bark as a main ingredient in their soil and that seems to work just fine.
 

leatherback

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Yes, decomposing bark takes nitrogen; I thought this was well known? I do not worry about it, because I regularly add fertilizer to my pots.
 

Peter44

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This is an interesting subject and I don't mind researching it a bit. I know about nothing about soil amendments. According to Jack, none of his bark is composted. That means that it is sapping nitrogen out of the soil as it decomposes. How much does it sap...no clue, but if you are looking for a certain % nitrogen to work on your trees, so you apply it, and the bark is sapping some out, then the formula is screwed up and you really don't know what % of nitrogen you are getting. If one is going to sell "bonsai soil" then would it not be better to have the correct components to start with? It's not like composted bark is rare or anything. If bark decomposing saps out 1/2 of 1% of the nitrogen that you add, then there is no sense worrying about it. If, on the other hand, it saps out 5% then there could be a problem. Leatherback, do you know what % nitrogen is sapped out by non-composted bark? I'm going to make some calls and see if I can find out. Any info appreciated. Thanks, Peter
 

leatherback

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there are several academic studies on the amount of n to be added to raw bark if you want to create optimal composting conditions. i would guess that is what is taken out. Not sure whether it is a real issue at the levels of bark used and the amount of fertilizer normally given. but then again, i do not try to know what my plants need. i just give them plenty. which works as none of my trees are in final refinement levels.
 

Peter44

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Here is what the experts say:


Soils and bark amendments added:

Q: Recently, I read that wood mulches can deplete the soil of nitrogen as they break down. Is this true? If so, what can I add to the soil to compensate for this nitrogen depletion? Or is there another kind of mulch you would recommend that is readily available? Would it be OK to mulch using the fallen leaves of live oak trees? -- Karen Shaw

A: "The nitrogen is not actually depleted, it's temporarily tied up. This can happen when organic materials low in nitrogen, such as shredded wood chips or pine bark, are incorporated into the soil. The microorganisms that utilize the low-nitrogen organic matter as food (decaying it) must obtain the nitrogen they need from somewhere else. They take nitrogen from the soil and, in doing so, tie it up in their bodies as their populations surge. When the organic matter is largely decayed, and the food runs out, the microorganisms begin to die. This returns the tied-up nitrogen back to the soil, with the added benefit of decayed organic matter. The problem arises during the decomposition phase. At that time, so much nitrogen may be tied up in the bodies of microorganisms that plants are unable to obtain all they need to be healthy. This leads to pale leaves and stunted growth, symptoms of nitrogen deficiency.

To keep this from happening, the gardener can do one of two things. First, the organic matter can be composted before use. That way the decomposition process has already occurred, and the addition of the material will not lead to tied-up nitrogen. Or the gardener could simply add a nitrogen-containing fertilizer at the time the organic matter is added. That way, there will be enough nitrogen to satisfy the needs of the microorganisms and the plants. Granular general purpose fertilizers, such as 15-5-10, or organic fertilizers like blood meal or cotton seed meal would be fine.

Now, for your situation, you can simply ignore everything I just said. That information applies when you incorporate organic matter into the soil. When you use low-nitrogen organic materials for mulch, such as cypress mulch, wood mulch, pine bark mulch, pine straw or fallen leaves (oak leaves make an excellent mulch), nitrogen tie-up is not an issue. The organic matter is applied on top of the soil and interacts with only the very surface of the soil. It decomposes slowly at the surface without affecting available nitrogen levels down in the bed."

All of this may sound mute to some, but it does bother me a bit that the soils are being made and sold with incorrect materials in them...why not just use composted bark to begin with? It might also be a concern that the nitrogen in the soil is being tied up for several years and then it is released and you are still fertilizing and so you trees get a double whammy of nitrogen or something. I would think we would all like to have a more controlled situation than that. I'll talk to Jack.
 

Peter44

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Even IF Jacks Douglas fir bark were "green" and it robbed nutrients as it composts
surely nitrogen is reconstituted as you feed. You do feed your maples right?
Also I'm pretty sure you can buy your own components for less at BJ's than pre made
and you'll have better control as to what amount of X each tree or species gets.
Conifer Blend:
32% 1/4 inch Douglas Fir Bark, 32% 1/4 inch Pumice, 15% 1/4 inch Lava, 15% 1/4 inch Monto Clay (1/4 inch Turface) and 6% 1/4 inch Horticulture Charcoal.
Yes your idea of just buying the components is good, but I don't own a warehouse, a mixing bin, or have a 5 acre nursery. I grow a few trees and it is so simple to just buy several bags of pre-made/pre-mixed soils verses having a garage full of soil amendments. I'm sure Jacks will get it right here.
 

Leo in N E Illinois

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As Peter said, bark that has not been composted does have a nitrogen demand. The bark is only around 30% of his mix. I have used similar mixes. I personally don't worry about it. The demand is more than 1% but it is not huge. My solution is to use the health of the trees in front of me to determine my fertilizer schedule. If I see trees looking a little yellow, I fertilize them. If they are all a lush green, I don't worry about it.

Also - decomposing wood, uses nitrogen more quickly, in a greater quantity at first, then quickly tapers off demand as it crumbles away to nothing. Fir bark has a less dramatic demand for nitrogen, and the need tapers off over a longer period. It lasts a good 5 years in a bonsai media. Heat treated radiata pine bark has a low initial demand, and is very decay resistant, and will last more than 7 years.

All in all, I just don't worry about it. Spot fertilizing the recently repotted tree that looks a little yellow is easy enough to do.
 

Peter44

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I sent jack the "SOILS AND BARK AMENDMENTS ADDED" article as above. Here is his reply...

Good read. Thanks for sharing. BN forums are great. He is exactly right. Bark that is not composted will take up to two years before its completely viable. I would love to add decomposed bark but the particles would be similar to organic potting soil and we would lose at least two of our 7 stamps. We strictly manufacturer gritty mix at this time.

The stamps he is talking about allow him to ship to all 50 States. I think it is the "decomposed" thing that causes a problem with the stamps allowing him to ship to all 50 States.

Also I think Leo is probably correct in that the new bark does not cause enough nitrogen retention to worry about. I could easily ask Jack to only put in half the fir bark and then add compost for the other half. Just curious about how all this works. I understand a lot better now! Aren't you glad???
 

penumbra

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My experience has been that fresh wood mulch and wood chips do rob a little nitrogen but it varies considerably. I have not seen instances where pine or fir bark has in any way significantly robbed nitrogen.
 
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