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shakiro
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 Posted: Sun Jun 01, 2008 9:15 am Post subject: nitrogen fixating bacteria |
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Sometime ago (Dec 7, 2007) there was a discussion in this group about
manure, and as a sideline the topic of nitrogen fixating bacteriae came
up. It was said that it would be unprobable that the nitrogen would be
fixed in the compost, because "Main N-fixers are cyanobacteria and
legumes. Both rely on sunlight."
Now I>ve been reading a little bit about it, and the name of two nitrogen
fixating bacteriae came up, who can be mixed either with the seeds at the
time of germination, incorporated in the soil directly, or mixed through
the compost in the last stage of maturing.
The names of those bacteriae are Rhizobium and Azotobacter. They don>t
really seem to be needing direct sunlight.
Thanks. |
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Phred
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| Posted: Sun Jun 01, 2008 6:57 pm Post subject: Re: nitrogen fixating bacteria |
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In article <pan.2008.06.01.04.07.47@shake.it>, shakiro <shakiro@shake.it> wrote:
[quote]Sometime ago (Dec 7, 2007) there was a discussion in this group about
manure, and as a sideline the topic of nitrogen fixating bacteriae came
up. It was said that it would be unprobable that the nitrogen would be
fixed in the compost, because "Main N-fixers are cyanobacteria and
legumes. Both rely on sunlight."
Now I>ve been reading a little bit about it, and the name of two nitrogen
fixating bacteriae came up, who can be mixed either with the seeds at the
time of germination, incorporated in the soil directly, or mixed through
the compost in the last stage of maturing.
The names of those bacteriae are Rhizobium and Azotobacter. They don>t
really seem to be needing direct sunlight.
[/quote]
Bacteria in the genus _Rhizobium_ are the typical "root nodulating
bacteria" which form a symbiotic association with the roots of many
species of legumes where they are responsible for fixing atmospheric
nitrogen -- hence the "nitrogen fixing ability" of legumes.
Species of the tree genus _Casuarina_ are also capable of fixing
nitrogen through a similar symbiotic association with root nodules of
_Frankia_ spp. You can find a bunch of references on this at:
<http://www.cmlr.uq.edu.au/t_madsen.html>
I can>t comment much on _Azotobacter_, but I think they are indeed
free-living bacteria capable of fixing almospheric N.
Quite a number of organisms are capable of N-fixation by one means or
another (i.e. directly or by association with another plant). You can
find a list of [some?] of them at:
<http://academic.reed.edu/biology/Nitrogen/Nfix1.html>
Cheers, Phred.
--
ppnerkDELETE@THISyahoo.com.INVALID |
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