I expect you may be largely correct, but I'll make a small rebuttal just for
the sake of disseminating information.

First, I don't think of soil as being a solid, immobile medium. The kind of
organisms involved in decay are mobile, so the nitrogen reduction effect may
involve more volume of soil than just that at the surface of the sawdust
particles.

Secondly, the nitrogen bound up in the sawdust becomes slowly available in
future months and years. This is a good thing. Lots of nitrogen all at
once is a bad thing. We've all heard of burning crops and lawns with
soluble nitrogen. What we don't hear about is the devastation of micro
flora and fauna in the soil - earthworms for example.

I find that weeding is going to disturb some of the plants' roots, whether
rogueing or cultivation. A shallow cultivation with sawdust added is going
to reduce the upper level nitrogen concentration temporarily, then release
in slowly in future. This is a good thing, but probably a minor
contribution to any immediate solution of the problem.

I do expect that watering is the number 1 remedy in this situation, but
especially if the soil is well drained.

Tom Ellison

wrote in message
...
In article , Tom Ellison wrote:
Dear Jeny:

I woke up thinking about sawdust. Just on the off chance, I recommend
you
avoid walnut sawdust. It seems black walnut (juglans nigra) produces a
substance that inhibits growth of other plants. Sort of biological
warfare.
I don't recall hearing this is true of other walnut species, however.
Just
not sure. Anyway, there's not likely that much walnut being sawn.
Also, I
believe it is the roots that exude the substance, so there may be much
less
in the wood or the leaves. I don't know if this survives curing the
wood.
I just avoid everything walnut.

Another very small issue. If you have excess acid in your soil and use
oak
sawdust, which contains tannin (adds acid to the soil) you may want to
add a
small amount of lime. This is almost a vanishingly small issue.

Tom Ellison

I don't think the sawdust will help since the nitrogen is already being
taken up by the roots and the sawdust can't get there without deep
tilling which would damage the roots.

Watering might help, but you also stand the chance of drowning the
plants. I sidedressed to early with nitrogen one year and the okra was
head tall before it put on the first bloom. Since then I make a point
of not side dressing until after the plant is putting on blooms.

The only exception is corn. I try to side dress it with nitrogen when
it is between 6 and 12 inches tall. It seems to encourage early root
growth and makes it withstand drought better. You should always cover
nitrogen with dirt to keep from losing so much back to the air.


"Raleighgirl" wrote in message
. com...

"Tom Ellison" wrote in message
...
| Dear Jeny:
|
| Moderately heavy watering may leach off some of the excess
nitrogen. I
| would consider this to be an "experimental" treatment (not
something I have
| tried). Also, clean sawdust, when it starts to break down,
uses some
| nitrogen to get started decaying, so this might bring down your
N levels
| temporarily. This is also an experimental treatment. But,
except for
| possible overwatering (depending on your soil's drainage) these
suggestions
| should be inexpensive and not dangerous.
|
| Do not get sawdust from sawing particle board, plywood, or
creosoted or
| other treated woods. You don't want to add unspecified poisons
to a food
| crop! Avoid all types of adhesives and wood treatments.
|
| Tom Ellison
|
|
Ok, we'll try it! Thanks Tom.






--
Wes Dukes (wdukesNOatSPAMpoboxdotcom)