Sawdust for a garden?

[terri46355]

Someone told me they used sawdust to make vegetable garden beds. Due to the massive amounts of rocks in the ground, I'd like to build more raised beds without having to purchase another load of "black dirt", which is more clay than dirt. There is a small sawmill near us with free sawdust.

Can you use black sawdust to grow vegetables, or should you mix it with manure or compost?

How long will it take green sawdust and manure to break down enough to plant in it?

I really don't want to purchase dirt. I haven't tried planting in sawdust and horse manure and would like opinions on the possibility.

[Darren]

We bought some property that a saw mill owner had spread sawdust so that it was 8" or more thick. It took 5 to 6 years before anything grew on the sawdust treated areas. We looked into tilling chicken manure into it, but 20 acres was too much. When sawdust rots it monopolizes the nitrogen in the soil. If you can get sawdust that has rotted to the point it's close to humus it would be better. But fresh sawdust or that which is only a year or two old can kill your near term soil fertility.

In some cases you might get away with using it as a mulch. I wouldn't use it for a bed. You might want to look up Ruth Stout and her methods. The book Lasagna Gardening is a great source for raised beds.

[francismilker]

Depends on what kind of wood made the sawdust. Pine and cedar sawdust are really acidic whereas others are not. It doesn't help much though until it begins to decompose either way. It's best to till it in right after spreading it. A good soil sample to let you know how much lime to add to it is well worth the time and money.

[Dexter]

I believe two parts brown (sawdust or brown leaves) to one part green (grass clippings etc) mixed well and composted will do the trick.
Sawdust may require a bit more green to the ratio. However too much green will create a mucky/poor textured, poor draining, slimy, stinky mess.

Then check pH and correct if required. Most compost is acidic by nature, not a terrible thing during the cooking process. Lime will neautralize and speed it up, though.

I don't know where manure fits in, I guess it depends how much bedding(brown) is mixed in.
I have had some amazing gardens in just mixing halfhazardly heaps of manure, grass clippings, leaves, old hay etc etc. First year is weedy but incredibly productive.
No it isn't ideal, but by the second year, it is unbeatable.

[Katey]

Back when I was farming, a friend of my father's came up with an old booklet (WWII vintage, as I recall) that gave specific amounts of nitrogen you needed to add to counteract the nitrogen-thieving effect of adding fresh sawdust to your soil. The booklet stayed with the farm and the ex, but Eric Sideman, the "extension agent" for the Maine Organic Farmer's and Gardener's Association, got a copy. You could call him.

[Ken Scharabok]

I've read spreading a goodly amount of limestone at the same time will offset the acidity in the sawdust.

[culpeper]

Your sawdust should be used to start a large compost heap (or, better, several smaller ones). With the added green waste (lawn clippings, leaves etc), vege scraps, newspaper and whatnot added, it will break down more quickly and be a more pH-balanced mixture with more nutrients. Compost can be dug into existing soil, a quick way to amend the soil and add nutrients, or it can be used as a mulch which eventually breaks down further and gets into the soil.

[willow_girl]

If you have access to an equally amount of manure, you have the keys to a heavenly garden!

Figure on a season for it to decompose into rich black dirt.

Layer it (lasagna-garden style). You can go ahead and plant in it before it's fully rotted.

[just_sawing]

I convert a few ton every year so this is something that I think I know about.
1 Sawdust buried over about 4 inches goes anaerobic and will not break down.
2 sawdust by it's self uses the nitrogen available and then stalls in the break down.
3 Sawdust absorbs water so you need more water than a person would think to get it breaking down.
It takes one year (six months is not uncommon) for me to convert raw sawdust to top soil. What I do is enlist my neighbors cattle to help I take the dust to his farm and spread it where he feeds large round bales of hay. They stand day and night doing the two things that cattle do the best. Since they mill around they are constantly stirring there byproduct into the dust.
In the spring we pile it up and it is black and rich. When we go by the pile with equipment we turn the pile for extra aeration.

[Terri]

Sawdust will compost and settle WAAY down.

The gent at this site http://gardeningrevolution.com/ uses 1/3 peat moss in his raised beds because it will not break down. I intend to make a raised bed this winter and I will use 1/3 vermiculite instead of peat moss.

[JJ Grandits]

Years ago , for a long time (19 years) I worked in a nursery and healed in all our plants with raw woodchips we got from the power company and various tree trimming companies. As time went by it broke down into humus and formed a very thick, muck like soil. It was fertile but was very heavy and drained poorly. It grew mountains of earth worms. You could not use them for fishing because they fed so heavily their bodies were like over plump boiled sausages. As soon as you touched them with a hook they would split in half. If you are patient it will work. I would use a fair amount of composted manure with it. We put down about 6-8" a year and between lining out the rows it got tilled in pretty good. I never did a soil analysis on it, and being in a nursery the plants came in and left pretty regular so I can not say how it would do for vegetables but any suppliments would be easy to add. Good luck.

[QuiltingLady2]

No don't do it. WE have raise beds - 42 of them. They have a sawdust ground cover between the beds. When the children have played in the garden and have put sawdust in the bed we have a very poor outcome for that crop. Maybe it's just our sawdust. I wouldn't do it.

[JJ Grandits]

It has to decompose first. Adding compost and a high nitrogen fertilizer will get things moving faster.

[Old Vet]

I used to work at a nursery and we added sawdust to the fields for humus. We put 1/4 inch and later we had to put 100 lbs per acre of 24% of nitrogen on the beds to make up for the nitrogen lost. It was good for humus but not for really making soil for about 2 years.

[Dexter]

If you grow blueberries and rhodos, mulch them with it. They can handle it as is.

Terri- reconsider adding vermiculite (or peat). Both are expensive AND nutrient defficient. It is a "medium" rather than a "soil" if that makes sense. It's great for potted plants, helps with drainage.
You can get where you want with better ammendments (manure/bark mulch/leaves/grass clippings).

And YES you can compost sawdust just fine, but do find out the tree type in case it is one that doesn't. Walnut may have plant toxicicity issues and I heard cedars rot too slow as well. They may be others.

[Silvercreek Farmer]

We used wood chips but I figure sawdust might even work better. Similar to Just sawing's method but you don't have to move it. Build a pen the size you want your garden, then put about 6 inches of chips and/or dust in it. Stock it with pigs (what we used) or chickens, once the chips/dust are well mixed with manure, add another 6 inches and so on until you have all depth you want for your final garden. If you still want to do smaller raised beds you can dig out the paths later on. In a year you should have some pretty good soil, plus eggs and or meat!

[ronbre]

go ahead and used your sawdust to build your raised beds..but add plenty of nitrogenous materials as well..or you won't get good crops..i also agree that adding the lime or wood ash will also help ..but the more things you can find free to add to your beds the better..look for lots of stuff...myself i use it all, sawdust, woodchips, shredded bark, as well as the nitrogenous things like manure and weeds and clippings, ashes and char, etc..the more the merrier

[fishhead]

If you can wait a year put a 12" layer of sawdust in the chicken pen and let them fertilize it and work it for a summer. It should be good to go the next year.

[Quercus21]

I have a small wood shop and so we have a fair amount of chips. Eventually the chips end up in the garden. Some first make a stop in the chicken coop as bedding, then the compost pile. Some go on the compost pile, by passing the chickens. The third is directly to the garden and depending on the time of year is how they are used. The chips are from air dried lumber, no chemicals (pressure treated, paint) etc. Sometimes, its from the planer to the compost pile, chicken coop or garden. Our garden and the rest of the property is clay, nothing but clay, and more clay. We are slowly in the process of creating "dirt" in our garden. It's working and it's going to take time.
If you are getting sawdust/chips from green lumber, I would let it brake down for close to a year. Mixing it with compost material (leaves, household, garden etc.) during this time.

[rambler]

The wood needs to break down into organic soil bits.

This tends to releace some acid type substances, and uses _huge_ amounts of nitrogen.

Once the breakdown is over, you end up getting much of the nitrogen back - but not before it all breaks down. It gets help prisoner by the break-down process.

This is the _very_ short version of what will happen.

Very few plants like acidic soil, and an acid soil does not allow basic nutrients (N, P, K, other micro nutrients) to flow out of the soil and into the roots of plants.

All green plants need some nitrogen - most crops need a lot of it.

So - the wood sawdust will build up your soils - 5-10 years from now.

The period between then and now - you will sorta end up with a desert type soil - won't grow a thing.

After all the sawdust breaks down, it turns into organic material. Typically soil is 1-12% organic material. About 3-6% makes good soil for growing crops. So if you spread 8 inches of sawdust on your fileds - in 10 years you'll still be down to your original rocky soil, with about a 1/4 inch of organic material lightly worked into the soil, better than it was, but still rocky and perhaps a bit more acidic than it was.

Adding nitrogen (manure) and lime (to raise the ph if you have low ph soil to begin with) and mixing the sawdust/manure/lime with the top 4 inches of your soil will help the breakdown happen in 2-3 years, and give better results.

Using sawdust or corncobs or the like as livestock bedding mixes the high-carbon materal (the sawdust) with a high-nutrient high nitrogen material (the manure) early on, and left in a pile for a year makes a really good soil additive. Or even fresh, it won't hurt the soil if you spread it fresh, as it is a good balanced ration of carbon & nitrogen that can break itself down without hurting the soil.

Just spreading the sawdust on the ground in deep piles makes it starve for the nitrogen it needs to break down, and takes a long, long time.

Not anything you wanted to hear or that helps you, right?

Long term the sawdust would help you, but it will be a long time or you need to do a lot of expensive work to make it a short time; and then you are still left with your rocky poor soil as the basis of your soil anyhow.

--->Paul