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Restoring Arbuscular Mycorrhizal Fungi in Agroecosystems: Oats
(Avena sativa) Shows Promise as a Cover Crop
Mike Lehman, Wendy Taheri, & Shannon Osborne U.S. Dept. of Agriculture - Agricultural Research Service
Brookings, South Dakota
What’s a Cover Crop? Legume
- Clovers - Vetches
- Peas
Grass - Ryegrass - Oats
- Sudangrass - Winter rye
Brassica
- Turnip - Rapeseed
- Radish - Mustard
Why Cover Crops?
Free Energy, Carbon, Nitrogen
Better infiltration
More storage
Less water erosion
Less wind erosion
Promoting Arbuscular Mycorrhizal Fungi with Cover Crops
Arbuscular Mycorrhizal Fungi (AMF)
• Form obligate relationships with >80% plants
– Most crops, excepting the Brassicas
Source: Dr. Wendy Taheri, USDA-ARS
AMF nearly eliminated in Ag Soils
Tillage
Seasonal Fallow
Annual Fallow
Monocropping, simple rotations
Inorganic fertilizer application
Fungicide application
Soil Compaction
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Agriculture Prairie
AM
F Sp
ore
s/5
0 c
c so
il
AMF Benefits for Agriculture
Low #s can stress plant Improve production
Acquire P, Cu, Zn, other nutrients Reduce fertilizer
Increase Tolerance Disease
Reduce pesticides
Drought, salinity
Improve soil structure Reduce erosion
Root
Fungal spores, hyphae, and glomalin
Photo credit: Sara Wright
0
5
10
15
20
25
30
35
40
45
50
AM
F P
rop
agu
les/
10
0 g
So
il 2009 2010 2011
Soil Propagules: Brookings, SD (Fall) Soybean - Small Grains/CC - Corn
Soil Propagules: White Lake, SD (Fall, 2009)
0
2
4
6
8
10
12
14
AM
F P
rop
agu
les/
10
0 g
So
il
BD
*
Soybean - Small Grains/CC - Corn
% Colonization of Corn Following Cover Crops (2010, 2011)
76
78
80
82
84
86
88
After Wheat After Oats
% R
oo
t C
olo
niz
atio
n
Average all
cover crop
treatments
Soybean - Small Grains/CC - Corn
AM
F D
ive
rsit
y Cropped Field
Prairie
Capturing AMF Diversity with Cover Crops
1
1 1
1 0
0 0
0
1 0
2
3
3
5 5
Wheat
Oat Clover
Vetch
Fungal: NS1, 4
AMF: AML1, 2
Classified with validated
reference database (Krüger et al.,
2012)
79.5Rhizophagus
4.8Diversispora
3.6Funneliformis
Wheat
Acaulospora
Rhizophagus-a
Diversispora-a
Funneliformis-a
Unc Glomeraceae-c
Unc Glomeraceae-h
Paraglomus-a
Unc Claroideoglomeraceae-c
Glomus
79.5% of all the sequences were Rhizophagus-a.
Diversispora and Funneliformis each had about4%;
combined they made up 88.0% of the sequences (n=83)
37.8Acaulospora
15.9Rhizophagus
18.3Funneliformis
13.4Claroideo-
glomus
OatAcaulospora
Rhizophagus-a
Rhizophagus-b
Viscospora-a
Diversispora-a
Funneliformis-a
Claroideoglomus-a
Claroideoglomus-b
Paraglomus-a
Paraglomus-b
Glomus85.4% of the sequences were in the four largest OTUs,
Acauolospora, Funneliformis-a, Rhizophagus-a and
Claroideoglomus-a (n=82).
Acknowledgements
• Dr. David Douds
• Mr. Kurt Dagel
• Ms. Ann Qualm
• Mrs. Sharon Nichols
Research funding:
U.S. Dept of Agriculture, Agricultural Research Service
South Dakota Corn Utilization Council