Billy wrote:
songbird wrote:
Billy wrote:
songbird wrote:
...
i would be interested in a good list of studies
done on actual nitrogen uptake from soil using
tagged sources (radio isotopes?).

so far in my readings i have come across one
study mentioned (which i didn't follow up on)
that said very little of applied nitrogen from
chemical fertilizers actually is taken up by
plants, but that it must act somehow by freeing
other nitrogen in the soil/organisms that plants
can take up. this was consistent for both
the first and second year after application...

so i'm curious if anyone else has gotten into
this topic beyond the surface?

Didn't like my thumb-nail on organic gardening?

considering that is what i've been doing the past
few years why would i not like it?

however, i was off on a tangent asking if anyone
knew of any actual studies using nitrogen isotopes,
as i did not track down the one i ran across in my
winter readings... i meant to write down the author,
title, etc. and then had to take the book back to
the library. silly me.


What are you on about? Are you looking for the fate of the applied NO3-,
or what?

nitrogen isotopes used in studies of actual
nitrogen uptake by plants.

yes, the fate of applied nitrogen compounds,
but actual studies of tagged compounds using
nitrogen isotopes.

i've come across only one reference so far in
my readings and was wondering if anyone else here
had come across any other studies of this type.


Ammonium ions are positively charged and therefore stick (are sorbed) to
negatively charged clay particles and soil organic matter. The positive
charge prevents ammonium nitrogen from being washed out of the soil (or
leached) by rainfall. In contrast, the negatively charged nitrate ion is
not held by soil particles and so can be washed down the soil profile,
leading to decreased soil fertility and nitrate enrichment of downstream
surface and groundwaters.

yes, but this is different than what i am asking
about.


The ecology of the soil
encapsulating the life and death cycles in the microorganisms, as well
as their symbiotic relationships with the garden plants is what nurtures
plants naturally (think slow release). One of the problems with chemical
fertilizers (chemferts) is that they are water soluble. Clay in the soil
will mitigate this to some extent by ionic bonding, but, by and large,
the the chemferts get washed away to become someone's else's problem
(blue babies, ocean dead-zones).

what is annoying about much of the extra nitrogen
problem is that it is largely preventable.

Especially with the implementation of organic farming methods.
....


songbird