Scott

Certainly, if you tilled fresh woodchips into the soil of your garden, I'd anticipate N deficiency for a year or two, and surface application of woodchips might be problematic for annual vegetables/flowers, but trees? They're a win-win proposition. There's evidence that the N-competition provided by fresh woodchips *may* serve to inhibit weed seed germination - another boon.

I have used fresh stable manure, composed of over 90% fresh wood chips, for 30 years with excellent results. Mulch improves the soil both around fruit trees and garden vegetable crops, both by holding in moisture and promoting earthworm activity, which is a definite soil builder. Suppression of weeds is a nice bonus.

I never mix fresh organic materials, even leaves, into the soil because that would consume nitrogen, but on the surface it does not, at least according to the results I have seen. I apply wide rings of stable manure, fresh from the riding stables, often over six inches thick. One year later, it has turned into black humus, but it has to be on the surface to do this.

Don Yellman, Great Falls, VA

Goog that up and it will answer your question convincingly that fresh is fine for trees. Why would N ever be an issue for trees when it can almost effortlessly be compensated for?

Aged is good too, but breaks down that much quicker so it actually is arguable that it's not as practical as fresh. I'd stay away from black walnut though, it takes quite a while for its chips to be toxin free.

The best mulch is the one that is free and local.

I'm going to take advantage of it and mulch my trees this spring with a big maple I am getting chopped down next week. The tree guys will leave it as mulch for free, can't beat that.

Scott

More wood chips please.

Isn't the problem with Black Walnut the roots and what they exude, not the above ground portion of the tree? I'm not certain.

Michael

Actually all parts of the wood tissue contain juglans, as well as the hulls. However, it may be that the roots contain higher concentrations. I don't know, but it wouldn't surprise me.

Scott, I've read that many times also and then someone told me that aged chips suck up just about as much N as fresh as they are far from composted and still heavy on the carbos. I think in soils with poor drainage where roots are right near the surface there may sometimes be an N problem though.

I've had difficulty in the past establishing trees where I've incorporated mellowed stable waste into the ground. It surprised me because I assumed the urine and manure in the mix would compensate adequately, creating a good C/N ratio, but it did not.

I have used wood chips forever, and for fruit trees they are the best mulch, bar none. And that is because they last a long time and protect the soil temperature, moisture, and organic content for a long time. The other mulches disappear much more quickly. The same goes for most perennials.

Wood chips in large amounts (say, one foot to the dripline) will provide sufficient long term nutrients, including N fixed by decomposition of the wood chips. The possible exception is K, and Boron, since long term cropping tends to remove a lot of them.

If you fear nitrogen is being sucked from the soil you can add manure like suggested or nitrogen fertilizer pellets. My guess is if you plants are nitrogen deficient you would recognize via lack of healthy green leaves and little spring growth.

My county extension agent said to keep the mulch from touching the trunk and extend it past the trees drip line.

As far as the bear goes, I am experimenting with one of those scarecrow motion activated sprinklers and suspect it might work in your case as well (except when below 32 F !).

Woodchips will not supply adequate N for establishing trees, IMO. The point is that they don't remove it to any appreciable depth. After the organisms that digest it die the N required for the decomposistion gets recycled and available again but I don't believe you'll have a net gain from the chips.

By adequate N I mean what's needed for optimum growth.

Scott

If you do use leaves, its probably worthwhile to put them in a garbage can and then run the weedeater in there for a couple of minutes. Unlike pine bark, aspen leaves seem to green up the trees really well for unknown reasons.

I get most of my heat from wood so I can tell the nutrient content of wood by the amount of ash- although not the specific nutrients. The smaller the wood the greater the ash.

Full composting requires a C/N ratio of about 30, so you can see that the amount wood chips will produce is not negligible either. It will just be very slow. In my experience it takes about 4 years in Michigan to fully turn wood chips into soil, although weeds will start appearing in the bed in 2 years.

I know also because I grow mushrooms. I have just had a giant fruit fly infestation in my basement, when some spent mushroom bags (injected sawdust) which I was holding to inject some logs, went bad. Where did all those rotting nitrogen-rich compounds come from? Each bag is about 5 lbs clean sawdust with one cup of colonized sawdust as starter.

In Merwin's trials, hardwood mulch was added every three years (4 inches). Says in the early years the mulch did tie up some N, but he didn't allude to any problems it caused. After 8 years the mulched trees began to outgrow the others. After 12 years the repeated mulch applications developed a thick layer of humus full of tree roots just above the mineral soil. He likened the layer of humus to a vein of coal. Says the decaying wood chips add approx. 100 lbs. of N/acre. Also adds P. After 17 years the organic matter went from 4.5 to 9%. As Hman has pointed out before, the rich soil did not translate into extra fruit, but did translate into extra pruning. He also had some minor problems with nutrient leaching. However, considering that all orchard floor approaches have their pluses and minuses, he stated it was the second best way to manage an orchard floor.

Personally, I like to use wood chips. The alternative for me is to use lots of herbicide and install drip. Although it may tie up some N, I've not noticed any lack of vigor from fresh wood chips. It's early on, and I may get to a point where the soil gets too fertile. But then again, I think of Don who has been mulching for decades with good results. Either way, if the trees get too vigorous, I can always prune with a chain saw :-)

Almost any wood should eventually give fairly abundant amounts of potassium (K) and calcium (Ca) given the high contents of these in wood ash.

I think that in areas where it rains during the growing season you should think twice about an annual application of mulch after the trees establish. At some point, as Olpea mentions (or mentioned that I often mention), you are juicing things up too much. I've gotten to that point with my peaches here and that's why I talk about it so much. I used to be very pleased with the vigor of my peach trees, but now I need to tone it down because fruit quality is suffering.

On established trees I usually only want a splash of N response shortly after bloom to feed the leaves that feed the fruit, not the leaves that feed new wood.

I'm beginning to come to the conclusion that mulch tends to retard new growth in my short season area. Lately I've been holding off on the mulch for brand new trees. There are big diurnal temperature changes in my high desert location, which mulch insulates into a generally very cool soil. I haven't noticed excessive vegetation from the years of mulching, but then I have pretty poor soil.

Anyway, I am of the opinion that obsessing over the type of mulch to use is pretty pointless. The main thing is to find something cheap, convenient, and harmless enough that you can use in enough quantity to make a difference.

In my orchard, I think that the primary benefit of wood mulch is to keep the soil moist in dry spells. Most of my trees are on a hill and I have found the areas without mulch are much much drier in the dry months than the mulched areas.

Scott

If mulch makes the soil excessively cool it might be better to use only well aged wood applied an inch or so at a time starting just before bud break so roots can establish into it as their growth surges in early spring. You could cover the thin layer with black landscape fabric to supress weeds and draw heat and lift the fabric up to gradually add more aged chips during the course of the growing season.

Or invent your own method!

Trees can't generate roots into raw wood but they love to grow into aged chips, and if you used them in this way they'd actually create a better growing medium, temp-wise, moderating the excessively hot soil during day and cool at night. Without the wood the trees won't even be able to use the surface soil.

This would create a warmer medium for roots to grow into rather than cooling the area already there. I can't remember exactly, but I think apple roots function best in soil temps in the mid '60s and peaches in the low 70's F.

In the forest, primary root activity occurs on the surface in the black humus layer in the early spring when the soil is cool and moist- as the soil warms and the top drys later in the season, root activity goes downward.

What I love about this forum is that it combines members experience with the research they encounter to provide a more complete understanding of how to use research to adjust to "events on the ground".

Thank you Olpea and Glib.

Note that certain fruit plants that like N, most notably kiwi and hardy kiwi, will do well with wood chips alone. I have sandy soil and I am sure a good amount of my N goes away. I note no particular excess growth. Those of you with clay will differ (I am sure the Cornell tests were done in clay).

The other thing is what nutrients are missing in chips. N deficiency is almost impossible to get. Same for P or Ca. But a single, say, peach tree may lose 0.5 to one pound of potash (K) per year, just due to harvest. Those are major losses which wood chips, at 0.1% K or less, will not be able to compensate.

Thanks Glib for the info.

Also, how long have you been mulching on your site? I didn't start to question annual mulching until after more than a decade of annual applications on a single site. There has to be a point where you can make any soil too rich. It is well known that this is directly tied to the soluable solid content of fruit. The article Olpea mentioned talked about extra pruning without extra yealds. Fruit quality undoubtedly suffered in this scenario.

Wood ash is useful as a fertilizer to improve the fertility of soils and as a source of lime to "sweeten" acidic soils. Freshly burned wood ashes contain about 30 percent calcium oxide, 5 to 6 percent potash (K2), and 1 to 2 percent phosphoric acid (P2O5). Wood ashes generally have 50 to 60 percent of the neutralizing value of a high grade pulverized limestone. Ashes from dense hardwoods such as oak and hickory are higher in lime and potash than ashes from lighter woods such as pine and yellow poplar.

The horticultural benefit of wood ashes lies chiefly in their potassium content. Potassium, or potash, is necessary for the healthy growth of fruits and vegetables. After nitrogen, it is the nutrient used in greatest quantity in plants, and wood ashes contain about 5 to 7 percent potassium.

Potassium gets concentrated in the fruits in most plants. N gets concentrated in the green parts. For tomatoes, too, even though you have to grow a whole green plant from scratch, you end up with an optimal nutrient profile of 3/1/6, because you produce so many fruits (rich in K, too).

Fruits also vary widely in K-content, which is why I chose a peach and not an apple tree as my example. Tomatoes and melons are amongst the richest, see the nutrient data below.
The only really K-rich organic amendment I have is spent wine grapes (I only make 30 gallons for myself, but the other guys come press their grapes at my place, so I get several hundred lbs). I mix them with wood chips to compost them through the winter, and place them in beds which will have fruiting vegetables.

Seems to me a wheelbarrow full of woodchips would have plenty enough K for a year of growth for most anytning when it's in addition to what's available in the native soil.

In all my years of tending trees I've never encountered a single case of K deficiency in fruit trees I manage, mulched or not. I'm pulling out an awful lot of peaches but most soil has quite a lot of K reserves to begin with.

This document describes peach leaves as containing on average, during the growing season, 2% potassium, which I think is a considerable amount.

I am not sure why leaves should enter in the discussion, perhaps I do not understand your point. But dried leaves, as can be collected in the Fall, are similar to wood chips in nutrients, 0.1/0.1/0.1/ or so. Fresh leaves have much more, yes, but not comparable to the 1% that some fruits have.

The wikipedia link below discusses K-deficiency and states right away that it tends to happen in sand. The UK link here gives you some numbers about K depletion by harvesting. Note it was done in loam only, but also note significant depletion by harvesting in some loams.

http://www.ca.uky.edu/agc/pubs/agr/agr11/agr11.htm

K is extemely mobile and dried leaves have already lost most of it so I see your point, but if fruit has 1% K and fresh leaves usually at least double that, you can't really say it's primarily concentrated in the fruit of any plant.

I get the impression that your nutrient concerns are based highly on theory but not on the practice of actually monitoring the issue in your own trees. Where do you live and how long have you been growing your fruit trees there. What are your actual experiences with nutrient managment? This information would help me evaluate the practical base of your concerns.

I manage trees in all kinds of soils from heavy clays to sand you could almost sell for kids sandboxes, and I think your concern about K deficiency may be exaggerated. I believe if you do an analysis of the loam created by wood chips you will find K content to be extremely high.

As far as wood chips being an eventual liability in a sandy soil by creating something too rich, of course that will happen eventually in any soil if you are adding organic matter more quickly than it breaks down. However if you live in a non-humid area you can manage this easily enough by reducing irrigation to deinvigorate the trees.

As I said, the soil of my own orchard is not rich to begin with and fairly coarse as well. It is only during wet summers that the super loam I've created becomes a liability for peaches. Last year I compared many sites for the quality of peaches, and consistantly found that the worse the soil the better the fruit. It was an exceptionally wet and cool growing season, however.

The only fact that I have, and that stuck the K hypothesis in my mind, is that at my place a number of veggies started growing much better after I started amending with wood ash regularly. I heat with wood so large quantities are not a problem. The same jump in production happened to five old pear trees after each received of order one bucket of wood ash per year. It could have been other things, I realize. But the original soil there is very poor, poor enough that nutrient kits do not record a value. It is beige sand, about 6 inches down.

What is your soil pH?

Most all the minerals trees need are in both ashes and wood besides adequate N if you are going for rapid growth (and I'm not talking about over time but the first few seasons).

If you want to carry on this discussion you should e-mail me.

I have a flowerbed in front, same soil, with all sorts of perennials (asian and daylilies, daffodils, monarda, flox, hyacinth, peony, moonflower, etc.). It received about 18 inches of wood chips over the years, and some dustings of wood ash. No fertilizer ever, and it looks very good. Wood chips really can give you the whole spectrum.

Well basically, you don't know. If they were running plywood through there, no. Also, you don't know what other solvents and cleaning agents may have been disposed under there over the years.

I'd be at least a little concerned about hantavirus based on your description, but I'm sensitized to that living in my area.

Let me put it this way: I wouldn't reject it out of hand, but I definitely would not go out of my way to get that stuff either.

Sawdust from a mill wouldn't tend to be as nutrient rich as an arborists chips but would still do a fine job of conditioning soil and beginning the afore mentioned humus layer. I've only seen it used for blueberries, where it worked well but see no reason not to use it for trees.

Still, if there are any arborists doing tree removal in your area, it's awfully nice to get a free delivery.

I get mine from a local "pallete" manufacturing company. Consider looking that word up in your regional Yellow Pages. This company recycles old palletes that trucking companys, warehouses, and such haul in. They get ground up into a decent average sized aggregate that seems to last for a good while without immediately breaking down or getting moldy. I like this aspect in that it lets in sufficient air to not stay to wet for to long. The old pallete material is in most cases well aged before making it to this stage of the process. This seems to help it last. I'm sure their are a good mix of wood varieties involved. So far no problems with any sorts of mysterious residually enhanced kill-off or die-back effects either!

It' not free. But $10.00 gets your pickup loaded in several quick scoops worth of a large skid loader, and your down the road with it. So that alone makes it well worth the minimal expense. They run it over a magnetic belt to remove the majority of nail remains. I can be as generous as necessary with any coverage needs via this option.

Not everyone will find a local source for this of course. I do actually consider myself lucky in regards to having this option. But where it may exist, it is both handy & cheap!!! ~ q3

From talking to the neighbor and some others around, it was just a small scale operation that the guy had in his back yard. He cut mostly rough cut pine and hemlock for local people. The only chemicals or anything that may have been there are diesel fuel and or oil from the saw head. I would think that would have been very minimal and it has been about a decade since in use.