This document provides an overview of cover crops and strategies for integrating them into a corn-soybean rotation. It discusses selecting cover crops based on the main purpose and cropping system. A low-risk introductory approach is to drill cereal rye into corn stalks, plant short-season soybeans into the rye, and then plant a low C:N cover crop mix after soybeans before no-till corn. This strategic approach aims to build soil health over time through biologically active cover crops matched to each cash crop.

1. Cover crops 101- How
and why to get started
Eileen Kladivko, Agronomy Dept., Purdue Univ.
Tom Kaspar, USDA-ARS, Ames, IA
Barry Fisher, USDA-NRCS, Indianapolis, IN

2. Cover crops in the Midwest
 Why cover crops?
 Many potential benefits- soil health, crop
productivity, water quality
 Why not used by everyone yet?
 Some risks and challenges, learning curve,
time constraints, costs, no short-term
economic gains

3. Rationale for cover crops
 A living, growing plant at times of year
when we normally have nothing
growing.
 Capture sunlight, feed soil organisms,
sequester carbon, trap and recycle
nutrients, improve soil health
 Make better use of the resources and
time available!

4. 7 Month “Brown Gap” for soybean and corn, fallow period
Cover crop grows and takes up N during
some of that normally fallow season.
This would shrink the “brown gap” and
keep the land green for longer time.

5. Cover crops are part of a system!
 Different potential benefits and
challenges for each type of cover crop
 Must adapt cropping system, including
nutrient mgmt, NT (tillage) system,
manure, pest mgmt, crop rotation
 Learning curve—need to do homework!

6. Outline for this morning
 Discuss cover crop types and benefits
 Considerations and checklist for getting
started in cover crops
 Suggest a low-risk introductory
approach to integrating cover crops into
a corn-soybean rotation

7. How select cover crops?
 What is your main purpose?
 What is your cropping / tillage system?
 Current cash crop and next cash crop?
 No-till, strip till, or other systems?
 What time windows are available?
 How will you seed the cover crop?
 Soil types, climate, drought, manure, herbicide
carryover, or other local considerations?
MCCC tool can help with these!—come to next session!

8. Grasses

9. Brassicas

10. Legumes

11. What are potential benefits?
What is your main purpose?
 Nitrogen scavenger (trap N that would
otherwise leach away)
 Save N for later use by cash crop
 Decrease N loss to drainage water
 Nitrogen producer (legume)
 Fix atmospheric N2 for use by plants

12. Benefits and Purpose (2)
 Reduce erosion
 Improve soil health
 Build soil organic matter
 Increase biological activity and diversity
 Improve aggregation
 Build macropores, permeability, deeper
rooting, reduce compaction
 Buffer soil from variable weather

13. Tap root extended another 18+ inches
beyond the end of tuber. These roots
are probably of more benefit for soil
structure and permeability than the
tuber itself.

14. Benefits and Purpose (3)
 Conserve soil moisture
 Recycle nutrients
 Weed control, pest suppression
 Extra forage
 Increase crop yields over long term,
and decrease year-to-year variability

15. Cover crops and N cycling
 Legumes—biological N fixation
How much N fixed? and released?
and when?
 Non-legumes—How much N trapped?
and released? and when?

16. N-scavenging crops
 Amount of biomass produced is key to
nutrient uptake—good stand, rapid growth
 Age/stage of plant when killed, determines
N%, C:N, plant composition, and therefore
decomposition rate (along with weather!)
Huge challenge!
 Cereal rye, annual ryegrass, wheat, oats,
barley, triticale

17. Residue Addition and N Availability
Avail.SoilN
Time
High carbon
residues added
Immobilization (tie-up) Mineralization
(release of N)

18. Residue Addition and N Availability
Avail.SoilN
Time
Low carbon
residues added
No Immobilization (tie-up) Mineralization
(release of N)

19. Organic material C:N ratio
Newspaper 120:1
Wheat straw 80:1
Corn stover 57:1
Rye cover crop, anthesis 37:1
Rye cover crop, vegetative 26:1
Hairy vetch cover crop 11:1
Soil microbes (average) 8:1
C:N ratios of common organic residues
C:N ratios wider than 25:1 cause N immobilization for some time
period. If utilizing covers with wide C:N ratios, then should either:
• allow time for decomposition before high N-using crop (corn)
• apply extra starter N
• don’t choose high C:N covers before corn

20. Resources
www.mccc.msu.edu
2nd Edition now available!
Purdue Extension Education Store
1-888-EXT-INFO
www.the-education-store.com
Cover Crop Selector Tools
(link on left sidebar)

22. Checklist for Cover Crops
• Initial Considerations
– Goals
– Educate yourself
– Current system
– Planning
• Spring / Summer before
• Late Summer / Fall
• Winter / Early Spring
• Spring

23. Initial Considerations – Goals
• Why do I want to do this?
• Cover crops are a long-term investment.
• More growth, more diversity, and bigger
window are good but don’t push that at first –
don’t go for the home run first time at bat
• Low hanging fruit – erosion control

24. Initial Considerations – Educate
Yourself
• Talk to other farmers – local is better
• Go to field days, workshops, and meetings
• Judge internet and magazine information
based on where you are and where they are
– newest, most exciting, or most sensational
information probably needs to “season” or
“age” a bit
• Experiment – learn as you go – adapt

25. Where is Iowa ?
Where does your information
about cover crops come from?

27. Initial Considerations – What’s
Your Current System?
• Current crop rotation and maturities
• Current tillage system – no-till and strip till
easier and leave more time
• Herbicide and weed control program -
residuals
• Equipment and logistics

28. http://extension.psu.edu/plants/crops/soil-management/cover-crops/herbicide-
persistence/herbicide-carryover-table

29. Initial Considerations - Planning
• Start small & easy – be ready ahead of time
• Decide on cover crop species – use
something somebody else has grown – single
species – available/inexpensive
• Planting plan – when/who/how/rate – backup
plan
• Herbicide/termination plan – when/who/how –
backup plan – err on side of caution
• Main crop planting - modifications
• Halftime adjustments – other team is weather

31. Spring / Summer Before
• Adjust residual herbicide plan if needed
• Plant targeted fields early
• Order cover crop seed well in advance
• Arrange for cover crop seeding services or
equipment

32. Later Summer / Fall
• Monitor main crop progress
• If aerial seeding before harvest, monitor
weather and soil moisture conditions
• If planting after harvest, harvest as soon as
possible and have cover crop planting
equipment and seed ready to go
• Adjust plan as weather and calendar date
dictate

33. Winter / Early Spring
• Look at stand, winter survival, and amount of
growth the previous fall
• Consider soil profile water storage
• Consider next summer’s residual herbicide
program for next fall’s cover crop
• Plan or arrange for cover crop termination

34. Spring
• Consider weather, soil profile water storage,
cover crop growth, and projected planting
times with regard to when to terminate
• Scout fields for insect pests. Consider
chemical control at time of cover crop
termination if necessary. Allow host-free
period if necessary – 2 weeks. Scout again.
• When planting cash crop monitor planting
and make adjustments to ensure proper seed
depth, seed furrow closure, and to prevent
residue pinning.

35. Midwest Cover Crops Council Website
http://www.mccc.msu.edu/

36. Cover Crops
…Strategies for a
Corn-Soybean Rotation

37. Strategically…
CC should complement the following crop
What about Corn?

38. Strategically…
CC should complement the following crop
…Which is better?
Corn into:
High Carbon
(Corn/Wheat)
…or
High N (Protein)
Cover Crop
(Clover/Peas)

39. Strategically…
CC should complement the following crop
Corn into:
High Carbon
(Corn/Wheat)
…or
High N (Protein)
Cover Crop
(Clover/Peas)

40. Strategically…
CC should complement the following crop
To Raise N (Protein)
Add: Clover/Peas
and consider:
Oats, Oilseed
Radish, Rapeseed

41. Strategically…
CC should complement the following crop
Corn into a mix:
High Carbon (Rye)
Provides Erosion
Control
plus
Moisture Savings

42. Strategically…
CC should complement the following crop
Corn into a mix:
High Protein
Provides Optimum
Nutrient Release

43. Strategically…
CC should complement the following crop
Corn into
a Mix of:
High C (carbon)
and
High N (Protein)

44. Strategically…
What about Soybeans?
Do Soybeans
need N ?
…Sure, but
they
capture
their own!

45. Strategically…
Soybeans do well into a high carbon Cover Crop.
…Why?
Weed Control, Late Season Water and Nutrient Cycling

46. Strategically…
CC should match desired C:N Ratio
Material C:N Ratio
rye straw 82:1
wheat straw 80:1
oat straw 70:1
corn stover 57:1
rye cover crop (anthesis) 37:1
rye cover crop (vegetative) 26:1
mature legumes 25:1
Balanced Microbial Diet 24:1
daikon radish 19:1
crimson clover 17:1
ryegrass (vegetative) 15:1
young alfalfa 13:1
hairy vetch cover crop 11:1
soil microbes (average) 8:1
GoodforCornGoodforSoybean

47. Strategically…
Planning the system
1. Drill or VT
Cereal Rye into
Corn Stalks

48. Strategically…
Planning the system
1. Plant a short
season
Soybean into
the Rye
(preferably early
in the season)

49. Strategically…
Planning the system
3. Plant a low C:N
mix into or after
Soybean

50. Strategically…
Planning the system
4. NT Corn into a
Biologically
Active
High Function
Soil

51. Strategically…
Planning the system
5. Enjoy The Rewards of
Soil Health!