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Re: [SANET-MG] Entrez PubMed Soil Quality & phosphate availability



Hello Jared, 
 
There are quite a few studies done with arbuscular mycorrhizas in the field.  To add to Joel's list, I would also include:
 
1. Kabir, Z. and Koide, R. T, 2002, Effect of autumn and winter mycorrhizal cover crops on soil properties, nutrient uptake and yield of sweet corn in Pennsylvania, USA, Plant and Soil, 238(2):205-215.
 
2. Boswell, E. P., Koide, R. T., Shumway, D. L.,Addy, H. D., 1998, Winter wheat cover cropping, VA mycorrhizal fungi and maize growth and yield, Agriculture, Ecosystems, and Environment, 67(1):55-65.
 
3.Cheng, X. M., Baumgartner, K., 2004, Arbuscular mycorrhizal fungi-mediated nitrogen transfer from vineyard cover crops to grapevines, Biology and Fertility of Soils, 40(6): 406:412.
 
As Joel mentioned, you can search for all the mycorrhiza literature on  the  Mycorrhiza Information Exchange database at http://mycorrhiza.ag.utk.edu/ <http://mycorrhiza.ag.utk.edu/> .
 
Sincerely,
michelle schroeder
 
 
 
Michelle S. Schroeder, Ph.D.
Assistant Professor, Agroecology
 
Crop Science Department
North Carolina State University
2406 Williams Hall
Campus Box 7620
Raleigh, NC 27695-7620 USA
 
Phone: (919) 513-0085
FAX: (919) 515-7959
Email: michelle_schroeder@ncsu.edu
Personal webpage: http://www.cropsci.ncsu.edu/personnel/Schroeder_Michelle/Default.asp?fmtinfo=1,450,150 <http://www.cropsci.ncsu.edu/personnel/Schroeder_Michelle/Default.asp?fmtinfo=1,450,150> 
Agroecology program: http://www.cropsci.ncsu.edu/agroecology/ <http://www.cropsci.ncsu.edu/agroecology/> 
 
 
 

________________________________

From: Sustainable Agriculture Network Discussion Group on behalf of Jarrod Gunn-Mcquillan
Sent: Fri 3/17/2006 11:29 AM
To: SANET-MG@LISTS.IFAS.UFL.EDU
Subject: Re: [SANET-MG] Entrez PubMed Soil Quality & phosphate availability



Does anyone know of any field studies using Mycorrhizae??  There seems to be
lots of greenhouse, microcosm etc. etc.

Thanks

-----Original Message-----
From: Sustainable Agriculture Network Discussion Group
[mailto:SANET-MG@LISTS.IFAS.UFL.EDU]On Behalf Of Dale Wilson
Sent: Friday, March 17, 2006 10:00 AM
To: SANET-MG@LISTS.IFAS.UFL.EDU
Subject: Re: [SANET-MG] Entrez PubMed Soil Quality & phosphate
availability


Hi Edna,

>> I'm afraid I'm over my head on this subject.  I'm interested,
>> but I understood maybe about half of what I read and my
>> unabridged dictionary didn't help me a whole lot....
>> Can anyone tell me if that is the take home message in this
>> research?

Unlike nitrogen and potassium, phosphorus in the soil is tightly bound
to the mineral fraction.  As water moves from the soil into the roots,
potassium and nitrogen and most other minerals are swept along into the
plant along with the water (yeah, I know, this is an
oversimplification), but not so with phosphorus.  The roots have to go
GET phosphorus by intimate contact with soil particles.  Most plants
simply cannot produce enough root surface area to get the phosphorus
they need, even when there is plenty around.  Almost all crops form a
symbiotic relationship with a class of fungus called "arbuscular
mycorrhizae fungi" (AMF).  The AMF live in the soil and have an
extensive network of fine mycelia.  As a young plant is established,
the root system becomes infected by the AMF which transports phosphorus
into the roots.

http://en.wikipedia.org/wiki/Arbuscular_mycorrhiza

"Mycorrhizae helper bacteria" work with the AMF to help dissolve P from
the surfaces of soil particles.  The abstract cited by Lawrence studied
an association between the AMF and the "growth-promoting rhizobacteria"
Bacillus subtilis and Entrobacter.

Here is the full text of the paper:
http://aem.asm.org/cgi/reprint/63/11/4408

Lawrence wrote:
> I interpret this to mean that the researchers discovered that the
> presence of a specific AM fungus innoculated with two phosphate-
> solubilizing ("helper") bacteria in soils with low phosphate
> bioavailability resulted in higher levels of plant available
> phosphorus and "significantly increased biomass and N and P
> accumulation in plant tissues".

I don't think this is a new finding.  The main point of the paper seems
to be the use the isotopic dilution method as a tool.  There is a lot
of literature about this subject.

> So, is anyone marketing a soil innoculant for organic and
> sustainable farmers who periodically apply rock phosphate to
> farmland with normally low P bioavailability (I assume this can
> be detected in a soil test)?

I wouldn't jump to the conclusion that inoculation with these organisms
in normal field situations will be beneficial.  I would try it out
carefully in designed experiments and distrust promotional literature.
AMF is normally present in most fields, and the bacteria mentioned are
rugged and extremely common in soil.  The paper does show why rock
phosphate (RP) might be more available to plants than one would think
from the soil chemistry per se.  I still would make sure my RP is
high-grade and finely ground.

Dale

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