[compost_tea] Biocontrol Agents and Microbial Inoculant Effects on SMC; APS poster by Larkin

From: Steve Diver <steved_at_ncat.org>
Date: Wed, 01 Sep 2004 22:26:31 -0000
Compost Tea List -

I have added this PDF item to the Files section.

R.Larkin-Biocontrol-SMC-APS-2004.pdf

It is the poster -- based on the following abstract -- presented
by Robert Larkin at the American Phytopathological Society
meetings in Anaheim, California in August 2004.  It is posted
here with permission.

Influence of Biocontrol Agents and Other Biological Amendments on
Soil Microbial Communities.
Robert R. Larkin.  USDA-ARS, New England Plant, Soil, and Water
Lab, University of Maine, Orono, ME.
htt= p://www.apsnet.org/meetings/2004/abstracts/a04ma0381.htm

The neat thing about Larkin's research is that it brings laboratory
and research skills to biologically-based approaches in terms
of "what works" in relation to soil microbial communities, or
SMC.   

Secondly, it examined Compost Teas and EM (Effective Microorganisms),
which need further exploration in the scientific literature.

I talked to Larkin and the poster is really a summary of several
research projects and papers.

They are looking at Biocontrol Products, Microbial Inoculants,
and Biostimulants and their infuence on plant pathogenic disease
control and their effect on soil microbial communities. 

Biocontrol Agents:
Bacillus subtilis (Kodiak)
Burkholderia cepacia (Deny)
Trichoderma virens (SoilGard)
Trichoderma harzianum (Rootshield)

Microbial Inoculants:
EM
EM-Bokashi
Compost Tea
Vermicompost for CT
AMF -- Arbuscular mycorrhizae mix

Biostimulants:
Vitazyme

The compost teas were made with the Earth Tea Brewer, according
to instructions with the vermicompost and nutrient pack supplied,
and foliar applied.   The foliar applications had no effect on SM= C.

This year, their have field trials underway and they've made one
broadcast application and one furrow application of compost teas,
in addition to regular foliar applications with compost teas.  They also increased the strength from the original 1:5 dilution.

They are also looking at efficacy studies of compost teas and
related microbial inoculants such as EM for late blight in potato
and so forth. 

The biocontrol agents reduced stem canker and black scurf
diseases and increased total and marketable yields relative
to the pathogen control.

The biocontrol agents and EM had significant effects on SMC.

An interesting conclusion is that biocontrol organisms can persist
in the soil thoughout the growing season and be recovered later.
Their effect on SMC were still evident one year after application.

Secondly, disease control is related to soil microbial effects in
general.

>From this, you can generally say that bioaugmentation with
either biological control products, with microbial inoculations.
or with humus farming management practices that encourage
and soil microbial growth can have long-term effects on soil
microbial communities and disease control.

In fact, a substantial part of their work is based on crop
rotations in broadacre potato production to examine the
cultural effects of crop rotations on SMC.    

The following paper in Soil Biology and Biochemistry goes
into this latter work in greater detail, including the soil
microbial assay techniques.

Characterization of soil microbial communities under different
potato cropping systems by microbial population dynamics,
substrate utilization, and fatty acid profiles 
Robert P. Larkin
Soil Biology and Biochemistry 
Volume 35, Issue 11, Pages 1451-1466 (November 2003)
http://dx.d= oi.org/doi:10.1016/S0038-0717(03)00240-2

Interestingly, Larkin's work on crop rotations in relation to SMC
is similar to Jerzy Nowak's research on the use of crop rotations
as a "soil priming" technique to manipulate the soil microbial community in advance of the forthcoming crop to ensure sufficient
beneficial microorganisms that provide biological control and
growth promotion. 

The Files section also has three papers from Jerzy Nowak,
posted previously. 

Also see:

Managing Soil Microorganisms to Improve Productivity of
Agro-Ecosystems
Gregory Welbaum, Antony Sturz, Zhongmin Dong, Jerzy Nowak
Critical Reviews in Plant Sciences
Volume 23, Number 2 / March-April 2004      &= nbsp; 
Pages:    175 - 193
http://dx.doi.o= rg/doi:10.1080/07352680490433295

Excerpt from Welbaum, Sturz, Dong, and Nowak:

"Soil structure, its overall health, and crop yield potential can
be modified by cultural practices. However, the concept of "soil
priming," which we interpret as setting the "readiness"
of a specific soil to receive a selected crop, is still new
(Yunasa and Newton, 2003). For example, the design composition
of a cover crop in a heavy life-mulch/no-till production system
(Morse, 1999) can include "primer plants" with deep, thick,
and fast-decomposing roots, providing channels (biopores) for
the establishment of soil microbial communities (Yunasa and
Newton, 2003).

Integration of legumes, which secrete compounds recognized as
signal molecules by rhizobacteria, into life-mulch will induce
the bacterial production of Nod factors (lipochitooligosaccharides)
essential for the establishment successful N2-fixing
legume–rhizobia symbiosis (Prithiviraj et al., 2003).

Submicromolar concentrations of these compounds induce
physiological changes in both host (legume) and an array of
nonhost plants by enhancing seed germination and early seedling
growth (Prithiviraj et al., 2003). Moreover, nodules of several
legumes produce high levels of hydrogen gas, which stimulates
proliferation of beneficial bacteria in the rhizosphere, improving
growth of cereals in rotation (Dong and Layzell, 2001; McLearn
and Dong, 2002).

Recent interest in the hydrogen-producing microorganisms
has been motivated by the potential for the biological
production of hydrogen gas for fuel (Kalia et al., 2003),
and options also exist for their use in conventional
agriculture."

Finally,

To explore related abstracts from APS, see:
http://www.apsnet.= org/meetings/abstracts.asp

Best regards,

Steve Diver
http://www.attra.ncat.org


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Received on Wed Sep 01 2004 - 19:04:10 EDT

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