Mulching Materials: What to use?

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In the past, I have used grass clippings but this year a friend came over and saw our big pile of sawdust/shavings from cutting firewood and said that we could use that for mulch in the garden. Is this true? Hubby thinks it would make the soil to acidic but would it if it was only used on top as a mulch? How about straw? Have alot of that too.

-- Lisa (tepeeclan@nidlink.com), May 13, 2001

Answers

Straw is very good mulch, wood of any kind will use up the nitrogen in the soil as it breaks down. So it should be composted first. The ratio of 1 part nitrogen (such as raw manure, blood, fish or green plant material etc;) mixed with 30 parts carbon (woody material chipped up, dry plant material like leaves, hay or paper etc;)

-- Thumper (slrldr@aol.com), May 14, 2001.

P.S. if the sawdust/chips are already rotted it would not use up the nitrogen like fresh does,

-- Thumper (slrldr@aol.com), May 14, 2001.

For plain mulch (on the surface, just to protect the soil) there's not that much chemical difference between straw or shredded newsaper or wood - they're all just inert cellulose and lignin, unless the wood/whatever is high in tannins or other acid (oak, pine bark, pine needles, etc). That's not necessarily bad either - if your plants can take it (say shrubs), the tannins can help keep weeds down. However, a lot of people mulch with material that will break down and also fertilise fairly quickly - compost, old rotted manure, grass clippings, hay. If you've got finely-divided wood, it will do whatever it's going to do a lot quicker than would wood chips, and if that is leaching organic acids into the soil then yes - the soil could get acid. If you can separate out shavings and chips from the sawdust, they should be OK as you said. I'd be inclined to pile the sawdust in a heap, mix manure (and your grass clippings) through it, and let it compost for a few months.

John from New Zealand made a comment in a very recent thread about using pine chips as a mulch. We do it a lot in Australia as well. They also sell chippers into which you feed your prunings, and make your own mulch.

-- Don Armstrong (darmst@yahoo.com.au), May 14, 2001.


I have to agree with Don.

I'll add that any carbon (wood chips or straw) will suck nitrogen out of the soil in order to compost.

I'll also add that while I might mulch some things with straw (things that are not nitrogen pigs), I would never mulch in the garden with a pine sawdust/woodchips because of the tanins. In fact, any compost I made with pine would not be used in my garden either.

-- Paul Wheaton (paul@javaranch.com), May 14, 2001.


please,please please...put your straw outside to get rained on,germinate and die first.My last years garden had the most gorgeous thick,lush bed of wheat you have ever seen!!!!!I had heavily mulched with fresh from the barn wheat straw.

-- teri (mrs_smurf2000@yahoo.ca), May 14, 2001.


I use a 5-6 inch layer of large pine bark nuggets as mulch in our garden, have to use the big nuggets as the wind would blow away anything else!!! Also, the large nuggets don't rot as easy, and stay in place for years, so far, have had them in place for 8 years, and only have to add a bit every 3-4 years or so. Slugs are not a problem unless we have abnormally wet weather, then a little slug bait takes care of them.

Of all the various mulches, this has worked out the best for us, and is by far the cheapest in the long run, as it lasts and lasts. No rot means no nitrogen depletion. The number of earthworms in the mulched soil is amazing, and no tilling (ever!!!) is required. I purchased the largest bark nuggets that Walmart sells, in the 3 cubic foot size bags, takes a lot, but, again, lasts practically forever.

-- Annie Miller in SE OH (annie@1st.net), May 15, 2001.


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