Re: sawdust mulch [Online permaculture class: File: Nutrient Cycles: Sheet Mulch

In a message dated 1/25/97 10:49:26 PM, gregj9@intellinet.com (Greg Jarrett)

>Anyone with comments on using sawdust for a garden mulch?  I know the danger
>of tying up nitrogen, but I read that if it is not tilled in, the effect is
>very minor.  Since I am working toward a no-till garden, that should not be
>a problem.  
>The crop I am particularly interested in this method for is beets.  For weed
>suppression I need a very fine mulch that I can fill right in around the
>plants after they are thinned.
>Comments or other good ideas?
>  Greg Jarrett     gregj9@intellinet.com

Sawdust is perfectly safe to use as mulch providing that you have no plans to
till it in for several years.  I've used sawdust, wood shavings and wood
chips with no problems.   It is quite nice because due to N tie up in the
mulch area, weeds do not grow in it.  

I'll also relate two contradictory experiences.

1)  At the Community Organic Gardens in Ashfield, Massachusetts, USA, manager
Steve Tracey tilled in some mulch that had consisted mostly of shavings and
horse manure.  It is very common in that area to use wood shavings as stable
bedding.  I was on the project by the next growing season.  We plantes
spinach had had very chlorotic plants-typical nitrogen defficiency.  I dug up
some soil and there were lots of undecomposed shavings.  We were unable to
salvage the spinach and tilled it under and planted inoculated peas that did
just fine.  In other plots, where less sensitive crops were growing, we were
able to reverse the N defficiency symptoms and restore normal growth by using
dilute human urine for irrigation.  Basically it was organic hydroponics.
 This was fairly good sandy soil with high humus content and a history of
good organic management.

Case 2.  In my own garden in Orange Massachusetts, I had one area that was
permanent mulch.  We mulched with leaves people rake up in the fall, wood
shavings, shavings and manure similar to the example above, wood chips,
sawdust, and anything else whatsoever that came to hand and was organic and
free.  The "soil" was an area that had been filled and leveled using coal
cinders from the furnace some years past, obviously before they converted the
furnace to oil.  (The coal bins were still in the building.)  We had chickens
and turned them lose in the mulch garden the fall of the second season.  They
scratched so deep or worms that they dug holes deeper than they were tall.
 From a elevation of about 20 feet through the kitchen window, I could only
see the red comb go flying out.  Not only were they mixing the sawdust with
the soil but they were mixing the profoundly infertile coal ashes (clumps of
poverty grass less than 2 inches high spaced by 3 or 4 feet, that infertile).
 I figured we would be on nitrogen fixing legumes for decades there but
planted corn anyway because hey, we had a big garden and I was curious.  We
had beautiful corn.  The next winter I started spreading our urine on the
snow--easy to see if you have a uniform pattern--figuring that the deep mulch
would hold it and we would get a jump start in the growing season.  We never
irrigated the mulch garden otherwise, so that was the only urine it ever got.
 That year we had a phenomenal garden (despite addition of more sawdust etc
and more chicken mixing) and I've photographs of the corn just breaking into
tassel next to a spading fork with giant squash blossoms and thriving
volunteer sunflower also in the picture.  At the base of the corn is the edge
of the sheet mulch area and you can see bits of the old newspapers sticking
out.  To the right is the unmulched area showing the widely spaced poverty
grass, with a bit of clover that has developed in one area where fertilizer
was spilled or scratch out of the garden.  It is like a desert and a jungle
growing with a line separating them.  The jungle had received sawdust mulch.
 While I used other kinds of mulch, I took no trouble to spread the sawdust.
 I'd take a few boxes saved by inmates at the prison where I taught, and just
dump them where I wanted the mulch a little deepr.  Clumps of sawdust were
visible in the spring. (Probably not the best scratching areas for chickens.)

I've always had success using sawdust on top of sheet mulch with blueberries.
 And I would absolutely avoid it on my gardens that get double dug from time
to time.  

Good luck.  (We have all this and other tips written up in an extensive soil
management issue of our journal.  email for details)

For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since
1982), Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and now correspondence
permaculture training by email. Copyright, 1996, Dan & Cynthia Hemenway, P.O.
Box 2052, Ocala FL 34478 USA  YankeePerm@aol.com  

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