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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

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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

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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