Use of Sawdust/Chips

[RayH]

Obviously a newbie question: Does anyone have information on the use of sawdust/chips for plant mulch or for inclusion on a compost pile? As a southern boy I grew up believing that any wood on the ground was termite bait. However, several of my bride's gardener friends have asked for limited amounts of my leftovers for gardening use. This all assumes "clean" wood -- no cca, composites, etc.

Opinions are welcome along with facts.

Thanks,
Ray

[gordonmt]

I have used sawdust and planer "peices" in my garden as mulch for years. Plants love western red cedar, oak, and most pines, but stay away from walnut.
Last year, I incorporated some sawdust into my plant beds and in the spring, I could till up the ground using a hand spade. It also keeps the weeds down as a top mulch. I save up my dust through the winter and come springtime, I'm one of the most popular guys on my street because I share.

[Ray Martin]

Sawdust is what I make best. I toss it into the natural areas around the property. I have no idea if it's termite bait, but I do plant the stuff far enough away from the house (I hope).

There are a couple of landscape experts on the board... Maybe DaveO could chime in here with what we should be doing for the landscape / mulch / etc.

Ray

[DaveO]

Ray, my recommendation of what to do with sawdust and chips except those from Walnut is to put them into a compost pile/bin, add a little nitrogen fertilizer and let them age a bit before putting them out into the garden. The rational behind that is the high carbon to nitrogen ratio of raw cellulose (chips and dust) will actually pull available nitrogen from the soil to fuel the microbes that are breaking down the carbon. By pre-breaking it down in a "fertilized" pile you can avoid that nutrient draw.
Walnut should be avoided because of it's allelopathic Juglone compounds which can inhibit the growth of some plants. Walnut isn't the only plant that has this effect, but it the most common one used by woodworkers. Tree of Heaven is also Allelopathic.
One of my professors in college did a study on the extent of the allelopathic effect of Juglone from crushed Walnut leaves, and found that only a few commonly grown garden plants were effected by it. But Tomatoes and anything in the Solanaceae family (including peppers, potatoes, petunia) were highly effected.
So it's best to just avoid it.

MTCW,
Dave

[Ray Martin]

Hey Dave,

For the nitrogen content... do we get anything from a garden store with loads of nitrogen? Or is there something in particular that works well?

And on other fronts... wood shavings is another mater entirely... I have a neighbor who is a bee keeper. He always asks for the shavings (planes, jointers). He uses them in his smoker pots to calm the bees when he services the hives.

Ray

[DaveO]

Originally Posted by Ray Martin

Hey Dave,

For the nitrogen content... do we get anything from a garden store with loads of nitrogen? Or is there something in particular that works well?
Ray

Any common granular fertilizer will work great. Just a handful of whatever lawn fert. you have on hand is fine provided it's not a weed-n-feed type with a pre/post-emergent herbicide additive.
This composting is really only worthwhile if you want to use the material in an area where you want plants to grow, like veggie and flower beds. If you use it in a natural area without cultivated plants then it is just fine to use straight out of the machine, DC or off the floor.

Dave

[scsmith42]

Hey Dave, I typically spread my shavings/sawdust around some large oak trees out in the pasture (trying to help the root system as these were leftover when I converted the forest into horse pastures). I'll usually put down 1 - 3" or thereabouts. Would distributing some amonia nitrate fertilizer (I have some 34% leftover from fertilizing my hay fields) around on top of the shavings accomplish the same thing that you recommended earlier? Do I need to mix it in or just leave it on top?

Second question - would a blended fertilizer, such as a 10-10-10 be a better choice than the nitrogen?

Thanks!

Scott

[DaveO]

Originally Posted by scsmith42

Hey Dave, I typically spread my shavings/sawdust around some large oak trees out in the pasture (trying to help the root system as these were leftover when I converted the forest into horse pastures). I'll usually put down 1 - 3" or thereabouts. Would distributing some amonia nitrate fertilizer (I have some 34% leftover from fertilizing my hay fields) around on top of the shavings accomplish the same thing that you recommended earlier? Do I need to mix it in or just leave it on top?

Second question - would a blended fertilizer, such as a 10-10-10 be a better choice than the nitrogen?

Thanks!

Scott

The ammonia nitrate would be your best choice. The microbes really don't benefit much from Potassium and Phosphorus. Just broadcasting it on top would be fine. Keep the layer you place over the tree roots to less than 3" especially if it is fine dust vs. chips. The roots need to get air. And don't allow it to accumulate near the trunk, that can cause rot.
Dave

[scsmith42]

Thanks Dave!

[jeff...]

I'm working some black locust and wondered what Dave has to say about uses for the sawdust and chips. I understand it's quite toxic and I can say it must have something weird going on, the heartwood glows in the dark under a black light.

Thanks

[DaveO]

Jeff. Black Locust (Robinia pseudacacia) is indeed toxic, but that toxicity is only related to vertebrates (animals). It has no toxicity to other plants or insects. All of the plant with the exception of the flowers are toxic, but large amounts have to be consumed to have any ill effect. The flowers are quite edible, and tasty when deep fried (isn't everything). Also the flowers are a great source of nectar used by honeybees in making honey. For use as a compost material I don't think that it would be good. The heart wood has tremendous rot resistance due to the presence of several toxic flavonoides that prevent decomposition.
Why it glows under a black light I have no idea

Dave

[jeff...]

Originally Posted by DaveO

Jeff. Black Locust (Robinia pseudacacia) is indeed toxic, but that toxicity is only related to invertebrates (animals). It has no toxicity to other plants or insects. All of the plant with the exception of the flowers are toxic, but large amounts have to be consumed to have any ill effect. The flowers are quite edible, and tasty when deep fried (isn't everything). Also the flowers are a great source of nectar used by honeybees in making honey. For use as a compost material I don't think that it would be good. The heart wood has tremendous rot resistance due to the presence of several toxic flavonoides that prevent decomposition.
Why it glows under a black light I have no idea

Dave

Thanks Dave - I'm being extra careful with it wearing a dust mask and what not while working it. The dust does make my eyes burn a little, but that's not uncommon for me. Most wood dust makes my eyes burn till I get used to it, then I'm good to go...

Thanks

[Gofor]

Originally Posted by DaveO

Jeff. Black Locust (Robinia pseudacacia) is indeed toxic, but that toxicity is only related to invertebrates (animals). It has no toxicity to other plants or insects.
Dave

Question on the toxicity: Did you really mean "invertebrates" (i.e. worms, slugs, and other spineless creatures), or "vertebrates"?

Go

[jeff...]

Originally Posted by Gofor

Question on the toxicity: Did you really mean "invertebrates" (i.e. worms, slugs, and other spineless creatures), or "vertebrates"?

Go

He was talking about me "(i.e. worms, slugs, and other spineless creatures)"

[Bas]