cover crops 101 - kladivko
TRANSCRIPT
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
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
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!
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.
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!
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
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!
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
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
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.
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
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?
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
Residue Addition and N AvailabilityA
vail
. S
oil
N
Time
High carbon
residues added
Immobilization (tie-up) Mineralization
(release of N)
Residue Addition and N AvailabilityA
vail
. S
oil
N
Time
Low carbon
residues added
No Immobilization (tie-up) Mineralization
(release of N)
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
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)
Checklist for Cover Crops
• Initial Considerations
– Goals
– Educate yourself
– Current system
– Planning
• Spring / Summer before
• Late Summer / Fall
• Winter / Early Spring
• Spring
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
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
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
http://extension.psu.edu/plants/crops/soil-management/cover-crops/herbicide-
persistence/herbicide-carryover-table
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
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
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
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
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.
Strategically…
CC should complement the following crop
…Which is better?
Corn into:
High Carbon
(Corn/Wheat)
…or
High N (Protein)
Cover Crop
(Clover/Peas)
Strategically…
CC should complement the following crop
Corn into:
High Carbon
(Corn/Wheat)
…or
High N (Protein)
Cover Crop
(Clover/Peas)
Strategically…
CC should complement the following crop
To Raise N (Protein)
Add: Clover/Peas
and consider:
Oats, Oilseed
Radish, Rapeseed
Strategically…
CC should complement the following crop
Corn into a mix:
High Carbon (Rye)
Provides Erosion
Control
plus
Moisture Savings
Strategically…
CC should complement the following crop
Corn into a mix:
High Protein
Provides Optimum
Nutrient Release
Strategically…
CC should complement the following crop
Corn into
a Mix of:
High C (carbon)
and
High N (Protein)
Strategically…
Soybeans do well into a high carbon Cover Crop.
…Why?
Weed Control, Late Season Water and Nutrient Cycling
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
Go
od
fo
r C
orn
Go
od
fo
r S
oyb
ea
n
Strategically…
Planning the system
1. Plant a short
season
Soybean into
the Rye
(preferably early
in the season)