I have only a moment, but do want to comment since your question is a common one.
Too often fertililzers are lumped together wth toxic biocide chemicals in
considering what is acceptable for organic farming. If you are planning to spread
the sawdust-manure with a manure spreader, the most effective means of balancing
the C and N would be to mount a tank and sprayer on the spreader and spray a
solution of nitrogen, say UAN 30% N (urea-ammonium nitrate) onto the material as
it is being spread. [Some Biodynamic farmers may have such a sprayer set up for
inoculating manure and compost materials as they are spread]. Adding only enough
N (I doubt that the P and K in 19-19-19? would be necessary if there is some
manure mixed in with the sawdust) to bring the C:N ratio down from about 300 to
about 30 will certainly not harm either the soil or the rest of the environment.
In fact the N will not be in the soluble form for long as it will be rapidly used
by the microbes and converted to organic forms. This will promote the humification
of this material as well as expensive organic sources such blood meal. As to the
business ethics of the fertilizer company, well you can try to check around
concerning their reputation. I would not smear the entire industry, as such.
Finally, you could forget about the high C:N ratio if you apply this stuff to an
alfalfa field or other forage legume. A well nodulated legume will laugh at the
low soil nitrate caused by immobilization. In fact the sawdust might prevent the
leaching of excess nitrate from the legume (which can be just as damaging to the
environment as that leached from fertilizer). After several years, the legume
would supply sufficient N to humify the sawdust-manure material and allow some of
the organic N to mineralize.
I hope this helps. I have tried to fully explain the details and the principles
underlying these processes in chapters 12-13 in The Nature and Properties of
Soils,12th edition (by N.C. Brady and R.R. Weil, 1999, Prentice Hall).
Kevin Smyth wrote:
> Thanks to all of you for your replies to my question re. the use of very
> sawdusty horse manure on our organic vegetable plots. Seems the best thing
> would be to incorporate this stuff into the plots this Fall, and add
> nitrogen in some form either now or next growing season. The problem is
> the lack of cheap sources of nitrogen. One of the responses I received
> said that "The problem is the mythos of 'organic' gardening. Offsetting
> this with synthetic fertilizer would be environmentally responsible and
> effective, but not 'organic'". Is this really true? I do agree that there
> does appear to be a lot of superstition among the fervent organic folks,
> and that many of them do not actually know as much as they think they do.
> But would it really be "environmentally responsible" for me to buy a
> truckload of Yieldbuster 19-19-19 synthetic fertilizer and spread it over
> my fields? Thats what most of the farmers around here do in their
> hayfields. I bet it would not have any detrimental effect on the
> environment of my farm to do this now and then, say every three or four years.
> But I am not certain about this. I am not certain about it because I don't
> know enough about such things.Does anyone out there know a lot about the
> effects of short term use of synthetic nitrogen fertilizers on soil and
> environmental health? What about the manufacture of the product itself?
> Would I be supporting an industry that is not environmentally responsible?
> I'm not sure, but I know what the organic folks would say. Does anybody
> really know much about the manufacture of nitrogen fertilizer? How is it
> done? Can it be done in an environmentally responsible manner?
> My dad would scoff and call me a "purist". What do the rest of you think?
> Thanks, Kevin Smyth
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