sarah@practicalfarmers.org 515-232-5661

Sarah Carlson

Practical Farmers of Iowa

Strategic Initiatives Director

Maximizing Cover Crops:

What We’ve Learned

from 10 Years of

Cover Crop Research

Cover Crop Time Lapse Video

November 14 – July 30

Equipping farmers to build resilient

farms and communities.

Member-led, non-profit organization 3,400 members

Barriers

to reaching

goals

Soil Nitrate Production vs. Crop Nitrate Uptake

In the shaded areas, the soil produces nitrate,

but there is no crop to use it.

As a result, some nitrate is lost to waterways.

March February

Rate of soil

nitrate

production

from native

soil organic

matter

Rate of corn or

soybean nitrate

uptake

The majority of nitrate used by

corn and soybean comes from

soil nitrate production. Corn gets

the difference from fertilizer

while soybean gets the difference

from legume fixation of

atmospheric nitrogen.

Adds

Cover

Crops

20132011 2012Farmer’s

Tile

YR 2

Cover

Crops

4R,

No-till

Not

Enough

ALL TOO COMMON

WIN – PFI Corn/Soybean

Farmer Members

(~1400/3300)

73% Use/Added Cover Crops

50% Use/Added Small Grains

WIN – Private Cover Crop Cost Share

Low-Carbon CornSustainable Soy

GOALS26,000 A of cover crop scaling to

188,000 A by 2023

WIN – Crop Insurance Premium Discount

• Three Year Pilot

• $5/A of cover crop discounted from crop

insurance premium

• Year 1 165,000A signed up

Iowa – 591,880A Illinois – 488,626 A Indiana – 794,724A

Win – Mapping Cover Crops in the “I”

States: ‘15 – ‘16

Win – Cover Crops Acres

760,000 A statewide in 2017

0

200,000

400,000

600,000

800,000

2011 2012 2013 2014 2015 2016 2017

Co

ver

Cro

ps

Acr

es

Total Acres (ILF Estimate 2014-2017)

Cost Share Acres (State and Federal)

Iowa Cover

Crop Acres

2015 – 2016

Iowa Rented

Farmland, 2012

“$30-$35/A cover crop cost protects

a $5000-$10,000/A asset.”

- Iowa farmer new to cover crops

Final NCR-SARE Project Report:

https://projects.sare.org/project-reports/lnc15-375/

1. Control Cover Crop Costs

2. Control Herbicide Costs

3. Avoid Cover Crop Establishment Failures

4. Avoid Redundant Expenses

5. Avoid Corn Yield Drag

6. Realize Soybean Yield Gains

7. Feed Cover Crops

Make Cover Crops Pay on your FarmFarmer-led Research Results from PFI’s Cooperators Program

54COOPERATORS TOOK PART IN 77RESEARCH TRIALS

IN 2018

Mix: $14.25/A

Rye: $10/A

1. Control Cover Crop Costs

61% Rye $10/A

48% Rye Mix $14.25/A

23% Oats $8/A

19% Oat Mix $32/A

Spring Nitrate Reduction and Seed Cost

•49 cover crop entries

•10-16 locations

•5 years

GRASS:

Cereal RyeBRASSICAS:

Rapeseed

LEGUMES:

Hairy Vetch

Cover Crop

Variety Trial

*60” wide corn spacing accommodates all

2. Control Herbicide Costs

Earl

y

Late

Earl

y

Late

Earl

y

Late

Earl

y

Late

REP 1 REP 2 REP 3 REP 4

Early vs. Late termination comparison

On-farm research design

Early = ~10 days prior to planting soybeans

Late = within 1 day of planting soybeans

Seeding soybeans into >7,000lb/ac cc

$30+$40+

Trt Cover crop? Herbicide Program

A No Full program

B Yes Full program

C Yes Reduced-cost program

D Yes No-residual program

Treatment Cost ($/ac)

Revenue ($/ac)*

ROI($/ac)

No-cover, full program 35.48 693.60 658.12

Cover, full program 66.73 667.59 600.86

Cover, reduced program

55.93 693.60 637.67

Cover, no-residual 44.60 693.60 649.00

*Soybean price = $8.67/bu (Nov. 13)

3. Avoid Cover Crop Failures

• Check herbicide label for potential carryover & grazing restriction

• Cereal rye only affected by 2x Dual II Magnum

• Vetch, lentil, and radish affected by:

– Balance Flexx, Corvus, & Hornet

• Atrazine, Callisto, & Laudis caused no injury

Armstrong, et al., Illinois State University

4. Avoid Redundant ExpensesFall Nitrogen Stabilizer vs. Cover Crop

5. Avoid Corn Yield Drag

12 participating farmers

from 2008 – 2018

*

*

*

*

*

*

*

*

-50

-40

-30

-20

-10

0

10

20

30

20

09

Je

ffer

son

20

10

Co

on

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ids

20

10

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lan

20

18

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on

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ids

20

17

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ffer

son

20

12

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on

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ids

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tie

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20

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Mar

ket

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ids

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ids

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lan

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tie

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eld

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d

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ket

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ket

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enfi

eld

20

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rt D

od

ge

20

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tie

r

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ket

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ket

bu

she

ls p

er

acre

Yield drag from cover crop (5/39)

*P ≤ 0.10

Yield neutral (31/39)

Yield advantage from cover crop (3/39)

Apply Sufficient N at Planting

Reduce Corn Seedling Disease Potential

Camelina showed no increased Pythium incidence

*

*

* * * **

* *

*

-20

-15

-10

-5

0

5

10

15

20

20

13

Co

on

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ids

20

11

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hes

ter

20

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ids

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20

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a

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son

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od

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ket

20

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son

20

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ids

20

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20

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eld

20

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20

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ter

20

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infi

eld

20

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ket

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a

20

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in

20

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ket

20

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on

a

20

10

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lan

20

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tie

r 1

20

17

New

Mar

ket

bu

she

ls p

er

acre

Yield drag from cover crop (2/29)

*P ≤ 0.10

Yield neutral (19/29)

Yield advantage from cover crop (8/29)

6. Improve Soybean Yield

Cover crops and soil health• Tea Bag

• Soil Decomposition Index

Dr. Marshall McDaniel, ISU

Teresa Middleton, ISU

Green tea

(easy to decompose)

Red tea

(difficult to decompose)

• Index = • % red tea decomp.

• % green tea decomp.

Cover crops and soil health

• The closer to 1.00, the healthier the soil.

• Soil under the cover crop was better able to decompose the red tea

(e.g., more microbial activity).

0.41

0.33

0

0.1

0.2

0.3

0.4

0.5

Cover No-cover

Soil Health Index -- Stout Farm

Photo: Fernando Miguez

7. Feed Cover Crop

https://www.extension.iastate.edu/agdm/crop

s/xls/a1-91economicsofcovercrops.xlsx

If we want to turn this….into this

cover crops need to pay today!

Get Started:

• https://www.card.iastate.edu/conservation/

• Join Practical Farmers of Iowa

• Attend PFI Annual Conference at Scheman

January 18–19, 2019

• sarah@practicalfarmers.org or 515-232-5661

Cover Crop Decision Tree