pine bark mulch - negative effects on soil?

[cleo88]

I've used pine bark mulch in my tomato beds in the past. I try to rake it off in the spring before I turn the soil over, but of course you can never really get it all out of there. Is this doing something to the ph of my soil, or having some other negative effect? If so, what is another cheap and not-unsightly way to prevent weeds and retain moisture in the soil?

[fortyonenorth]

Hi Cleo!

As long as it's pine bark and not wood, it shouldn't pose any problem. I would suggest fine-texured bark (pine bark fines) if you can get it locally. Many folks use PBF as a major component in container mixes and, if you use it as mulch, it could just be tilled in at the end of the season. Pine bark is slightly acidic, but not to the extent of peat. My understanding is that it contains calcium and magnesium as well.

Rich

[b54red]

I used pine bark fines to mulch my onions and had the best crop I have had in years. I am also adding it to the bed where I will be planting my okra because okra is such a heavy feeder that no matter how much manure and compost I add to the bed by the time the okra is finished it seems the bed is made of sand. I'm hoping the fines will keep the texture of the soil up and not disappear so fast.

[Tom C zone 4/5]

Bark mulch despite all the mythologic superstition that it (or wood) will steal all available nitrogen from your garden just isn't true.

The numbers of growers here who use bark mulch as a soil component in their containers. and I as a bonsai grower; would be very disapointed to learn that bark mulch has the power to strip our plants of fertilization, retroactively.

Who knew, Bark mulch can travel through time and undo past crops?

[tuk50]

I totally agree with what Tom C states in his post.. we live in opposite climates and my soil is devoid of humus, so I have added a product called mini nuggets.. pine bark chunks about 1/2in to 1in size and I also used a 10in layer of Christmas tree mulch provided by a city next to us for free every winter for a number of years and have been told this is bad because of the nitrogen robbing and acidic levels, but I strongly disagree.. it is only slightly acidic and works wonders in my soil. Also if you have access to any kind of nut hulls.. peanut, pecan etc. .. that stuff is also excellent as a mulch and addition to garden soil.

Fresh wood chips or saw dust will deplete the nitrogen. I know from experience and six cubic yards of sawdust horse stall bedding. I thought it would be okay because it had all the added nutrients the horses had deposited in the sawdust. After the remaining three cubic yards had composted in the pile for a year, it was great as a soil amendment.

Pine bark as in pine bark fines or pine bark nuggets works great without aging. I prefer the nuggets because they require more time to decompose. If you want a soil amendment to work fast, use the fines if available. If you want your soil to improve over an extended period, use the nuggets. I also seem to have fewer problems with insects attacking my plants from the soil up when I have a thick layer of pine bark nugget mulch. They seem to not like to lay eggs in the bark. That may not be scientific, but it has been my observation.

I stopped turning my beds over while adding amendments a few years ago. Now I simply add the nuggets to the top along with some compost and other organics. The earth worms seem to appreciate it.

The

Tom C,

I'm sometimes a little slow on the uptake. I haven't caught on to the retroactive part of gardening. Everything I do in my garden is for the future, not the past; unless I'm trying to correct past mistakes like adding fresh wood chips to my soil.

How do those bonsai's taste? Do they make a really big plant that needs staking or possibly a cage like a tomato?

Ted

[Tom C zone 4/5]

Snicker, Bonsai for all their diminutive size. Are (often) the spoiled children of old men.

The problem here if there is one, is there is I am sure there is a point at which the mycellia that convert wood to humus cannot work in a vaccuum.

Is that ten percent of the total volume of topsoil? Where by mushroom families cannot do their work?

I expect it is more near to 33%, being the tipping point at where soil fertility becomes interupted.

I have been adding crushed wood bark to gardens for decades. Only for the past fifteen to bonsai soil. Hugelkultur bed growers would also report conflicting experience.

I just have not seen the direct evidence of bark interfering with vegetable crops with any mesurable degree as the folks who claim to 'know cause they were told'.

A much more likely problem would be with hardwood chips that contain black walnut remains. Juglone is a well known aleopath.

If last years bark mulch didn't kill your garden, hows it going to do something different this year?

Untill I find in my direct trials that bark mulch interferes with garden fertility. I have to go with what I know.

Tom,

I think you are right. Pine bark fines and nuggets compared to the effects of chipped pine heart wood are two totally different critters in my garden. Walnut wood chips or bark would probably always be bad. I haven't used walnut products so I can't speak from experience. I probably would be reluctant to use any nut tree hardwood products in my garden. I don't know if pecan, hickory, and other nut varieties contain the same chemicals or the same concentration of those chemicals as Walnut, but I wouldn't want to take a chance.

I do use a lot of softwood in my soil amendments, but only after they are well aged. As you mentioned, the fungus and mycellia continue to be very healthy in my soil as well as the piles of agng wood products.

Ted

[tuk50]

tedln, I find it interesting about pine bark helping to keep down pests.... I've observed the same thing in my garden.. Couldn't find much about it on the web, but I do believe it has definitely helped my garden in that respect.. it makes sense that most insects don't lay eggs in it and it smells so much better than a pile of manure composting ... LOL.

[Stepheninky]

Originally Posted by tedln

Tom,

I think you are right. Pine bark fines and nuggets compared to the effects of chipped pine heart wood are two totally different critters in my garden. Walnut wood chips or bark would probably always be bad. I haven't used walnut products so I can't speak from experience. I probably would be reluctant to use any nut tree hardwood products in my garden. I don't know if pecan, hickory, and other nut varieties contain the same chemicals or the same concentration of those chemicals as Walnut, but I wouldn't want to take a chance.

I do use a lot of softwood in my soil amendments, but only after they are well aged. As you mentioned, the fungus and mycellia continue to be very healthy in my soil as well as the piles of agng wood products.

Ted

Actually not sure about the walnut bark either as my understanding is what harms the tomato plant is a chemical that is produced or given off by the roots.
Personally I too would avoid it as not wanting to be someone that test it. What I am saying is not sure the bark or the walnut wood itself even contains that chemical.

Fir and pine bark are for the most part neutral from a PH view so it really should have little to no effect. It also does not effect nitrogen. Though the raw (unbroken down wood) of both is a totally different story.

Its no myth put raw sawdust in your garden and it will have negative effects, Also most everyone knows bark is a good soil conditioner.

So it kinda seems like people are disagreeing to agree, We are all saying the basically the same thing just looking at it from a differing prospective.

An old Thai lady once taught me a valuable lesson about prospective. She asked me why I was eating a banana the way I was. I started at the steam end and peeled it down. I said everyone eats a banana that way. She told me in Thailand we start at the other end. The reason is that once we get towards finishing the banana we use the stem as a handle. Anyways neither one of us was wrong we just had a different perspective.

[dice]

This document on pine bark as a blueberry substrate in Georgia
has information on the physical properties of pine bark that
make it useful, the carbon-nitrogen ratio of both pine bark and
pine wood, and the pH of pine bark:

http://www.caes.uga.edu/publications...cfm?pk_id=7394

Edit:
Besides air space, the main difference between pine bark
and wood chips or shavings is the difference between a
material where the carbon comes from a high lignin content
(peat, coir, bark) and where the carbon comes from cellulose.
Despite having a much higher carbon-nitrogen ratio, the
cellulose based material (sawdust, wood shavings, wood chips)
breaks down to smaller particles faster, giving up air space
in the soil or container media.

[fortyonenorth]

That's an interesting article, Dice - thanks! I couldn't get the html page to open, but found the same document as a PDF here:

http://www.caes.uga.edu/applications...B%201291_2.PDF

[dice]

The html page opens ok here (Firefox 3.6.17).

The mention of internal air space in the bark was new to me.