Cover Crops to Improve Soil Health and Reduce Soil...

Cover Crops to Improve Soil Health and Reduce Soil Erosion

Dr. Eileen KladivkoAgronomy DepartmentPurdue University

Thanks to many colleagues over past 10 yrs!

Midwest Cover Crops Council www.mccc.msu.edu

Indiana Conservation Cropping Systems Initiative (CCSI)www.ccsin.org

Corn Systems and Climate CAPwww.sustainablecorn.org

http://www.mccc.msu.edu/http://www.ccsin.org/http://www.sustainablecorn.org/

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

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!

Cereal rye, SE Indiana

Outline today• Potential benefits to soil health• Examples of data on soil changes• Reminder of details being highly site-specific!

What are the potential benefits?(What are your main goals?) Nitrogen scavenger Nitrogen producer (legume) Reduce erosion Improve soil quality– aggregation,

infiltration, soil biological activity, rooting Increase soil organic matter (sequester C) Conserve soil moisture Recycle nutrients Weed control, pest suppression, extra forage Increase crop yields over long-term, and

decrease year-to-year variability in yields

Soil Health Indicators

Physical Chemical Biological Organic Matter

ChemicalPhysical

Biological

OM

Reviews used heavily for this talk

Kaspar, T.C., and J.W. Singer. 2011. The use of cover crops to manage soil. In J.L. Hatfield and T.J. Sauer (eds.), Soil management: Building a stable base for agriculture. ASA/SSSA, Madison, WI.

Blanco-Canqui et al. 2015. Cover crops and ecosystem services: Insights from studies in temperate soils. Agron. J. 107:2449-2474.

Classic purpose of cover crops—to cover the soil to reduce erosion Studies have measured reductions in soil

erosion and water runoff Protection of soil surface by living plants and

dead residues, even in NT Anchor surface residues, reducing their mvmt. Less detachment by raindrops, flowing water Increased infiltration Greater surface storage Slowed water velocity of runoff

Also reductions in wind erosion

NO COVER CROP OAT COVER RYE COVER

After Simulated Rainfall

Tom Kaspar, Iowa

Relative Erosion

Kaspar et al., 2001, J. Soil Water Conserv.

100

67

45

100

47

11

0

20

40

60

80

100

Rel

ativ

e Er

osio

n R

ate

(%)

Interrill Erosion Rill Erosion

Relative Rill and Interrill Erosion Rate in No-till Soybean as Affected by Cover Crops

No Cover CropOatRye

Kaspar et al., 2001, J. Soil Water Conserv.

Chart3

Interrill ErosionInterrill ErosionInterrill Erosion

Rill ErosionRill ErosionRill Erosion

No Cover Crop

Oat

Rye

Relative Erosion Rate (%)


100

67.2161172161

45.4212454212

100

46.5987942214

10.8946649983

Chart2

199719971997

199819981998

Control

Oat

Rye

Erosion Rate (tons/acre/hr)

Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops

47.8588

17.0236

3.5332

37.9016

21.8416

5.4604

Chart1

199719971997

199819981998

Control

Oat

Rye

Erosion Rate (g/m2/sec)

Rill Erosion Rate as Affected by Cover Crops

2.98 a

2.36 a

1.06 b

1.36 b

0.22 c

0.34 c

2.98

1.06

0.22

2.36

1.36

0.34

Sediment

199619971998199619971998199619971998

Control0.0240.0390.042aaa0.390.630.67

Oat0.0230.0190.036aba0.370.310.58

Rye0.0120.0150.022abb0.190.240.35

199619971998199619971998

Tracked0.0290.0340.036aaa

Untracked0.0110.0140.03bba

Sediment

Control

Oat

Rye

Sediment Rate (g/m2/sec)

Interrill Sediment Rate as Affectedby Cover Crops

0.024 a

0.039 a

0.042 a

0.023 a

0.019 b

0.036 a

0.012 a

0.015 b

0.022 b

Runoff

Tracked

Untracked

Sediment Rate (g/m2/sec)

Interrill Sediment Rate as Affected by Wheel Traffic

0.029 a

0.034 a

0.036 a

0.011 b

0.014 b

0.030 a

Infiltration

199619961996

199719971997

199819981998

Kaspar et al. 2001, J. Soil Water Conserv.

Control

Oat

Rye

Infiltration Rate (g/m2/sec)

Interrill Infiltration Rate as Affectedby Cover Crops

18.96

18.5

20.34

15.63

16.88

14.76

10.87

11.78

13

Relative Erosion


Control

Oat

Rye


Interrill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops

Rill Erosion

199619971998199619971998

Control13.0616.3921.14aaa

Oat13.5215.1420.24aaab

Rye11.6717.2519.02aab

199619971998199619971998

Tracked19.9720.3722.89aaa

Untracked5.5412.1617.37bbb

Rill Erosion

Tracked

Untracked

Runoff Rate (g/m2/sec)

Interrill Runoff Rate as Affected by Wheel Traffic

19.97 a

20.37 a

22.89 a

5.54 b

12.16 b

17.37 b

Total Cover

Control

Oat

Rye

Runoff Rate (g/m2/sec)

Interrill Runoff Rate as Affected by Cover Crops

13.06 a

16.39 a

21.14 a

13.52 a

15.14 a

20.24 ab

11.67 a

17.25 a

19.02 b

199619971998199619971998

Control19.015.610.9aab

Oat18.516.911.8aaab

Rye20.314.813.0aaa

199619971998199619971998

Tracked12.0511.659.13bbb

Untracked26.4819.8614.64aaa

Control

Oat

Rye



18.96 a

15.63 a

10.87 b

18.50 a

16.88 a

11.78 ab

20.34 a

14.76 a

13.00 a

Tracked

Untracked


Interrill Infiltration Rate as Affected by Wheel Traffic

12.05 b

11.65 b

9.13 b

26.48 a

19.86 a

14.64 a


Control

Oat

Rye



Rill Erosion g/m2/secInterrill Erosion g/m2/sec

19971998199619971998

Control2.982.36Control0.0240.0390.042

Oat1.061.36Oat0.0230.0190.036

Rye0.220.34Rye0.0120.0150.022

Relative Rate %Rill ErosionRelative Rate %Interrill Erosion

19971998Avg199619971998Avg

Control100100100Control100100100100

Oat365847Oat96498667

Rye71411Rye50385245

No Cover Crop

Oat

Rye

Relative Erosion Rate (%)


199719981997199819971998

Control2.982.36aaControl47.8637.90tons/ac/hr199719980.005

Oat1.061.36bbOat17.0221.840.2392940.189508** Assuming that rills occupy 0.5% of land area

Rye0.220.34ccRye3.535.460.0851180.109208

0.0176660.027302

1997199819971998

Tracked1.381.45aa

Untracked1.461.01aa

Control

Oat

Rye


Rill Erosion Rate as Affected by Cover Crops

2.98 a

2.36 a

1.06 b

1.36 b

0.22 c

0.34 c

Tracked

Untracked


Rill Erosion Rate as Affected by Wheel Traffic

1.38 a

1.45 a

1.46 a

1.01 a


Control

Oat

Rye


Rill Erosion Rate after 5 inch Rain in 1 hr as Affected by Cover Crops Assuming Rills Occupy 0.5% of Surface Area

199619971998199619971998

Control787681aaa

Oat797980aaa

Rye848185aaa

199619971998199619971998

Tracked747782baa

Untracked878182aaa

Control

Oat

Rye

% Total Cover

Percent Total Cover as Affectedby Cover Crops

78 a

76 a

81 a

79 a

79 a

80 a

84 a

81 a

85 a

Tracked

Untracked

% Total Cover

Percent Total Cover as Affected by Wheel Traffic

74 b

77 a

82 a

87 a

81 a

82 a

March 16, 2010, central Indiana.Surface shows some daikon radishes out of ground, some partially out of ground. Shows webbed appearance of dead leaves of radish.

Within a few more weeks, soil surface is bare—should not plant radishes alone, but combine with something else!

But cover crop species matters!

Tom Kaspar, Iowa

Corn silage land with and without a cereal rye cover crop

Keep your expensive soil on YOUR field!

Soil physical properties improved

Aggregation (esp. fibrous-rooted)– cover crop roots enmesh particles;

exudates feed microbes which then produce polysaccharides that “glue” particles together

Porosity, permeability (esp. tap-rooted) Deep roots, macropores, can aid water infiltration,

aeration, rooting

Soil surface protected, plus better aggregation, can mean less crusting or erosion

Roots give strength to soil for trafficability

Rorick, Frank, Kladivko

Cover Crops and No-Till Soil Structure

T. Kaspar, Iowa

Roots or shoots?

When building soil quality, esp. with NT, the cover crop ROOTS are probably more significant than the shoot growth

Still need good shoot growth for erosion control, mulch effects for moisture conservation, weed suppression, etc.

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.

Cover crops and soil organic matter

Potential to increase soil organic matter (SOM) or soil organic carbon (SOC) Greater inputs of biomass Less erosion losses Perhaps slower decomp., if wetter/cooler

Studies show slow increases (compared to no cover crop), or sometimes no change

Many factors affect the rate of change, and the ability to detect the changes—site specific

Factors affecting magnitude of SOC changes with cover crops (or any changes) Cover crop biomass production (more) Cover crop species, mixes, roots/shoots Years of cover crop use (more) Soil texture, initial SOC (clay) Tillage mgmt. (no-till) Climate (production, decomp., weather) Ability to detect– number of samples, strict

control of depth, variations w/ row position and short-term crop history, lab methods

~2500 lb/A~710 lb/A

Amount of growth affects the magnitude of cover crop impacts on soil or cash crop!

Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years

• A rye cover crop “increased” total soil organic matter (SOM) in the top 4 inches (10 cm) from 4.8% to 5.3%, or ½% change in SOM

• (spring biomass production ~2.8 Mg/ha after silage, 0.5 Mg/ha after soybean)

• 44% greater particulate organic matter (POM) in top 2 inches (5 cm)

• 38% greater potentially mineralizable N (PMN) in top 2 inches (5 cm)

These are really hard measurements to make – 400 cores in 3.7 acres Moore

Moore et al. 2014Iowa data

More examples of SOC changes

Using data from 37 studies worldwide, meta-analysis (Poeplau and Don, 2015) estimated gain of ~0.3 Mg/ha/yr to 22cm depth (approx. 0.01% yearly gain in SOC)

Blanco-Canqui (semi-arid), 0.1-1.0 Mg/ha/yrgain of SOC, cover+NT vs NT alone

Olson (IL), hairy vetch+cereal rye, sequestered: 0.9, 0.5, 0.1 Mg/ha/yr under NT, chisel, moldboard, respectively (12 yr)

Review by Blanco-Canqui et al., 2015, Agron. J. 107:2449-2474

Soil moisture

Effects on soil moisture are complex While living, cover crops transpire water, so

may dry soil more than fallow field—good or neutral or bad, depending……

After termination, cover crop residues often increase infiltration, decrease evaporation, leaving more moisture in soil for crop use. Can be benefit in summer.

Example soil moisture effects that sometimes occur.CCSI project; cereal rye terminated April 17; then corn grown.

~1000 kg/ha cereal rye at termination

Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa) • A rye cover crop increased soil water storage

capacity (plant available water) in the top 30 cm by 18%, which is equivalent to an extra 0.75 cm of water every time the upper 30cm of soil was rewetted by rainfall.

• The rye cover crop does use water in the spring, but in 5 out of 7 years this was replenished by the time of main crop planting.

• In most years after cover crop termination water contents in the upper 30 cm were higher following a rye cover crop in the summer.

Basche et al. 2015Basche et al., 2015

Effects on cash crop rooting?

Chen and Weil (2010, 2011) studied forage radish, rapeseed, cereal rye, vs no cover, under different levels of compaction

More corn roots grew deeper after radish and rapeseed > rye > no cover, in compacted plots

They suggested mix of radish or rapeseed for deep root growth, and cereal rye for surface mulch, as way to access deep water plus conserve surface moisture

Soil biology

Plant growth during normally “fallow” period (Sept-Nov, March-April) provides more food for soil organisms

Diversity of plant materials may also increase diversity of soil biological community

Soil organic matter maintained or increased

Purdue Univ.

Crusting inhibits seedling emergence, especially on low organic matter soils

Southeastern IN (SEPAC)

Evaluated practices to improve soil structure and crop productivity on poorly-drained, low organic matter, poorly structured silt loam

Earthworm populations were generally higher in: No-till vs. chisel Tiled vs. untiled Covers, rotation, manure vs. control

Soil physical properties tended to be improved by cover crops and rotation

Earthworm populations, spring 1994

0

20

40

60

80

100

120

140

160

180

200

Tiled-CH Tiled-NT Untiled-CH Untiled-NT

num

ber /

sq.

met

er

CCWRMNRO

Shallow-dwelling earthworm counts, after 10 years of treatments.Clermont silt loam, SEPAC

CC=Cont.corn, no coverWR=Wheat or cereal rye coverMN=Manure (mostly poultry)RO=Rotation with hay crop

Infiltration rate, tiled subfield, 1991

0

0.5

1

1.5

2

2.5

CC WR MN

stea

dy-s

tate

rate

(cm

/ hr

)

CHNT

Cont. corn Wheat or cereal rye cover

Manure (mostly poultry)

Other soil biology?

Evidence for greater biomass and/or activity of bacteria, fungi, micro- and meso-fauna

Arbuscular mycorrhizal fungi Soil enzyme activity Diversity of populations Methods for measurements, plus

interpretations for practical use, are still evolving. Potential is great but the impacts aren’t clear yet!

Potential impacts for Midwest/Ontario

Soil health and crop productivityConservation of soils resource baseWater qualityResilience to stresses from climate

variationsMagnitude of effects is site-specific!But much more work needed to take full advantage of the possibilities!

Resources

2nd Edition now available!

Purdue Extension Education Store1-888-EXT-INFOwww.the-education-store.com

Cover Crop Selector Tools(link on left sidebar)

www.mccc.msu.edu

http://www.the-education-store.com/

Cover Crops to Improve Soil Health and Reduce Soil ErosionThanks to many colleagues over past 10 yrs!Rationale for cover cropsSlide Number 4Cover crops are part of a system!Slide Number 6What are the potential benefits?�(What are your main goals?)Soil Health IndicatorsReviews used heavily for this talkClassic purpose of cover crops—to cover the soil to reduce erosionAfter Simulated RainfallRelative ErosionSlide Number 13Slide Number 14Soil physical properties improvedSlide Number 16Cover Crops and No-Till Soil StructureRoots or shoots?Slide Number 19Cover crops and soil organic matterFactors affecting magnitude of SOC changes with cover crops (or any changes)Slide Number 22Cereal Rye Cover Crop Effect on Soil Quality in a Corn Silage-Soybean System after 10 years More examples of SOC changesSoil moistureSlide Number 26Slide Number 27Slide Number 28Rye Cover Crop Effect on Plant Available Water after 12 years (Iowa) Effects on cash crop rooting?Soil biologySlide Number 32Slide Number 33Southeastern IN (SEPAC)Slide Number 35Slide Number 36Other soil biology?Potential impacts for Midwest/OntarioResources

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