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  • From: SCook21809 AT aol.com
  • To: market-farming AT franklin.oit.unc.edu
  • Subject: Re:Sawdust as Mulch:
  • Date: Mon, 31 Jan 2000 17:59:29 EST


Friends,
I have been reading the posts about using sawdust\woodchips as a mulch
and feel obliged to temper the advice being offered. In other words,
"WARNING! Proceed with caution."
I agree that sawdust and woodchips on the soil surface is much better
than turning it into the soil. Soil micro-organisms can be loosely grouped
into two families, bacteria and fungi. Only aerobic soil bacteria have been
shown to bind atmospheric nitrogen symbiotically in the presence certain
legume root exudates. Aerobic bacteria are incapable of using the complex
carbohydrates and lignins found in saw dust and wood chips as a food source.
They require simpler sugars and carbohydrates from sources like straw, crop
residues, compost and root exudates.
Fungi on the other hand, are very capable of dissolving the double and
triple bonds that hold complex carbohydrates together. Some fungi can
establish a symbiotic relationship with roots to exchange nutrients such as
boron, nitrogen, calcium, etc., that they transport from great distances to
the plant and trade them for root exudates. However, I am not aware of any
soil or composting fungi capable of binding atmospheric nitrogen.
In the Maritime northwest cedar chips are another threat to soil life
because it gives off a compound that kills bacteria and worms which is why
cedar doesn't rot. I suspect that locust chips may have a similar effect.
But I do not know. A very reliable authority on these questions is Dr.
Ingham at www.soilfoodweb.com.
My experience with wood chips and sawdust as a mulch is that they are
helpful for established perennial plantings. But they can have grave
consequences on annual crops. Use discretion, before you mulch your whole
growing operation with wood chips or sawdust.

Art Biggert
Ocean Sky Farm
Bainbridge Island, WA



  • Re:Sawdust as Mulch:, SCook21809, 01/31/2000

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