Legume Cover Crops: Why Does

the Variety Matter? Mtt Brook Wilke MSU Kellogg Biological Station, MSU Department of Crop

and Soil Sciences & EEBB PhD Student, 9156 N 40th St., Hickory

Corners, MI 49060, wilkebro@msu.edu, (269)615‐4573.

and Sieglinde Snapp

Michigan Organic Reporting Session: 3/6/09

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Legume Cover Crops

• Important source of nitrogen (and organic

matter) for organic vegetable and field crop

growers

• Very few species available for use during

Michigan winters (red clover and hairy vetch

are the primary two)

• Seed dis expensive

• Variable performance

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Cover Crop Research

• Greenhouse Characterization (2005)

• Three Field Experiments at KBS (2006 – 2008)

• Multiple li l On‐Farm Trials il in Michigan ihi and

Nebraska (2005‐2009)

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Red Clover vs. Hairy Vetch

• Coefficient of Variation between varieties for each of the two

cover crop species.

60

50

(CV)

40

Coefficient of Variation

30

20

10

0

N=6 Hairy Vetch (left) and Red

Clover (right) in Late April

Hairy Vetch

N=7 N7

Red Clover

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Red Clover vs. Hairy Vetch

• Cover Crop Biomass for two vetch and one clover

variety on 5/16/08

500

~150 kg N

per hectare

450

AG Cov ver Biomass (g g/m2)

400

350

300

250

200

150

100

~50 kg N

per hectare

~100 kg N

per hectare

50

0

AU Early Vetch Common Vetch Medium Red Clover

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Hairy Vetch Can Grow Really Fast

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Four Key Considerations When

Planting Hairy Vetch

1. Relative growth rates differ between varieties

depending on weather conditions and time

of year

2. Planting date is VERY important

3. Varieties i can be used for specific “cover crop

niches”

4. Variety mixtures are very useful for first‐time

growers

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Relative Growth Rate and Hairy Vetch

Hairy Vetch Biomass by GDD ‐ July Planting

Hairy Vetch Biomass by GDD ‐ October Planting

600

140

AG Cover Biomass (g/m2)

500

400

300

200

100

Common

Nebraska

April 16

May 1

May 16

AG Cover Biomass (g/m2)

120

100

80

60

40

20

Common

Nebraska

May 1

May 16

0

0

1600 1700 1800 1900 2000 2100

550 600 650 700 750 800 850

Growing Degree Days (Base 4.4 C)

Growing Degree Days (Base 4.4 C)

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Importance of Planting Dates

• Can common o hairy vetch be pa planted tedsuccessfully

u after soybean harvest in Michigan?

– No

• 2006/2007 Common HV planted AFTER SOYBEAN Oct

7 th , harvested on May 18 th

– 108 g/m 2 (~37.8 kg N / ha)

• 2007/2008 Common HV planted AFTER SOYBEAN Oct

9 th , harvested on May 17 th

– 25 g/m 2 (~8.75 kg N / ha)

• 2007/2008 Common HV planted AFTER WHEAT July

27 th , harvested on May 18

th

– 435 g/m 2 (~152.3 kg N / ha)

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Cover Crop Niches

– “Nebraska” grows fast early in the spring, and would be a

promising ii variety it for early incorporation (between April il15 th

and May 1 st ), whereas “Common” grows faster after May

1 st , and is ideal for later incorporation (after May 15 th ).

– “Lana” hairy vetch does not survive the winter in Michigan, but

grows very fast in the summer and fall after planting.

Thus, “Lana” produces substantial amounts of fall biomass and

creates a thick mulch layer, but prevents the need to spend time

and money killing the cover crop in the spring.

– “AU Early Cover” flowers earlier than the other varieties (as

early as May 15 th in one trial), making it ideal for no‐till organic

farming.

– “Minnesota” is a certified organic variety that is similar to

“Nebraska.”

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Cover Crop Niches

AU Early Hairy Vetch

Flowering by mid‐May 2007 Winter‐killed ‘Lana’ Organic ‘VNS’ Hairy

Hairy Vetch

Vetch from Minnesota

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Variety Mixtures

•Planting mixtures of varieties will

NOT necessarily increase cover

crop biomass

•Variety mixtures help to buffer

against environmental factors

unique to the specific farm or year.

Thus, growers can evaluate and

identify successful varieties for

their farm, considering their

specific needs. This concept may

apply to other cover crop species

as well.

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Acknowledgements

• NCR‐SARE for Funding

• Michigan State Plant Science Fellowship

• Present and Past Snapp Lab Members

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Hairy Vetch Variety Descriptions

• “Common” is a variety commonly sold in Michigan under the label of “Variety Not Stated.”

This variety has few leaf hairs and is produced in the Pacific Northwest, primarily in Oregon.

We obtained this variety from Michigan State Seed in Grand Ledge, MI.

• “Nebraska” is produced in Nebraska, and is also sold as “Variety Not Stated,” but may stem

from an old variety called “Madison.” However, “Nebraska” is much different than

“Common,” as it is much more pubescent (hairy) and is bred to be more cold tolerant, but

also grows slower during warm weather. We obtained this variety from Kaup Forage and Turf

in Norfolk, NE.

• “Lana” is a certified variety that was bred for Mediterranean climates such as that found in

California. This variety is sometimes called Woolypod Vetch, and is fast growing during warm

weather, but is not cold tolerant. We obtained this variety from S&S Seeds in Carpinteria, CA.

• “AU Early Cover” is a certified variety that was bred at Auburn University for its early

flowering characteristic, often two weeks earlier than other varieties. However, winter

survival lis mediocre in Michigan, and total t lbiomass production is less due to its dt determinate

t

growth pattern. We obtained this variety from Southern Proprietary Seed in Lake

Oswego, OR.

• “Minnesota” is a certified organic variety sold under the “Variety Not Stated” label. This

variety appears to be similar in form and function to “Nebraska,” potentially stemming from

an old variety called “Madison.” We obtained this variety from Albert Lea Seed House in

Albert Lea, MN.