Craig F. Drury*, W. Dan Reynolds*, Xueming

Yang*, Chin Tan*, and Neil McLaughlin**

Agronomic and Soil Quality Benefits

of Cover Crops

Agriculture & Agri-Food Canada

* Harrow, Ontario, Canada

** Ottawa, Ontario, Canada

OUR GOAL

Manage agricultural land to:

Optimize crop yield and quality

Minimize environmental N losses

Maintain and/or improve soil quality

Cover Crops

Benefits:

1. Increased crop yields.

2. Ability to capture residual N.

3. Ability to add N to soils through nitrogen fixation.

4. Improved physical quality (water storage,

transmission).

Brookston clay loam soil

Crop Rotations

Continuous crops Corn

Soybean

Winter Wheat

Winter Wheat + Red Clover

2 year Rotations Corn-Soybean

Winter Wheat-Soybean

Winter Wheat+Red Clover –Soybean

3-year Rotations

WW-Corn-Soybean

WW+RC-Corn-Soybean

Corn-Soybean-Soybean

4-Year Rotations

WW-C-S-S

WW+RC-C-S-S

Soil Inorganic N - Spring 2012 Soil Inorganic N (mg N kg

-1)

0 5 10 15 20 25 30

De

pth

(cm

)

0

20

40

60

80

100

Continuous Corn

WW-S

(WW+RC)-S

WW-C-S

WW+RC-C-S

Soil Inorganic N – Spring (0-60 cm depth)

WW WW-S WW-C-S

Soil

Inorg

anic

N (

kg

N h

a-1

)

0

50

100

150

200

Control

Red Clover

Winter Wheat Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Win

ter

Wh

ea

t Y

ield

(t h

a-1

)

0

1

2

3

4

5

6

WW

WW+RC

WW-C-S-S

WW+RC-C-S-S

75 bu/ac

50 bu/ac

25 bu/ac

Cumulative Winter Wheat Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Cum

ula

tive W

inte

r W

heat Y

ield

(t ha

-1)

0

10

20

30

40

Continuous WW

WW+Red clover

WW-C-S-S

WW+RC-C-S-S

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Win

ter

Wh

ea

t Y

ield

(t

ha

-1)

0

1

2

3

4

5

6

WW

WW+RC

WW-C-S-S

WW+RC-C-S-S

Corn Grain Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Corn

Gra

in Y

ield

(t

ha

-1)

2

4

6

8

10

12

14

Continuous Corn

WW-C-S-S

WW+RC-C-S-S

200 bu/acre

150 bu/acre

100 bu/acre

Cumulative Corn Grain Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Cum

ula

tive C

orn

Gra

in Y

ield

(t ha

-1)

0

20

40

60

80

100

120

Continuous corn

Corn-Soybean

W-C-S-S

W+RC-C-S-S

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Corn

Gra

in Y

ield

(t ha

-1)

2

4

6

8

10

12

14

Continuous Corn

WW-C-S-S

WW+RC-C-S-S

Soybean Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Soybean Y

ield

(t ha

-1)

0

1

2

3

4

5

Continuous Soybean

WW-C-S

WW+RC-C-S

70 bu/ac

50 bu/ac

25 bu/ac

Cumulative Soybean Yields

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Cu

mu

lative

So

yb

ea

n Y

ield

(t

ha

-1)

0

5

10

15

20

25

30

35

40

Continuous Soybean

WW-C-S-S

WW+RC-C-S-S

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Soybean Y

ield

(t ha

-1)

0

1

2

3

4

5

Continuous Soybean

WW-C-S

WW+RC-C-S

Surface Runoff & Tile Drainage Volume

M J N M J N M J N M J N M J N M J N

Cu

mu

lati

ve

Flo

w (

kL

ha

-1)

0

2000

4000

6000

8000

10000

12000

14000

16000

M J N M J N M J N M J N M J N M J N M

No cover crop + CDS

Cover crop + CDS

No cover crop + Tile drainage

Cover crop + Tile drainage

Surface Runoff Tile Drainage

1999 2000 2001 2002 2003 2004 20051999 2000 2001 2002 2003 2004 2005

Nitrate Loss

1999 2000 2001 2002 2003 2004 2005

M J N M J N M J N M J N M J N M J N

Cu

mu

lati

ve

Nit

rate

Lo

ss

(k

g N

ha

-1)

0

20

40

60

80

100

120

M J N M J N M J N M J N M J N M J N M

No Cover crop + CDS

Cover crop + CDS

No Cover crop + Tile drainage

Cover crop + Tile drainage

1999 2000 2001 2002 2003 2004 2005

Surface Runoff Tile Drainage

No CC+CDS CC+CDS No CC+Tile drainage CC+Tile drainage

Sa

tura

ted

hyd

rau

lic c

on

du

ctivity -

Ks (

cm

s-1

)

0.001

0.01

0.1

Saturated Hydraulic Conductivity (ksat)

Drury et al., 2010

Residual Soil Nitrogen (2006)

Treatments • Control (no cover crop)

• Oats (56 lbs/ac)

• Nitro radish (12 lbs/ac)

• Oilseed radish (12 lbs/ac)

• Yellow mustard (12 lbs/ac)

Planting date: Aug. 20, 2012

Cover crop study (2012)

Cover crop biomass - 2012

Yellow mustard Oats Oilseed radish Nitro radish

Co

ve

r cro

p b

iom

ass (

t h

a-1

)

0

2

4

6

8

10

12

Cover crop N uptake - 2012

Yellow mustard Oats Oilseed radish Nitro radish

Cover

cro

p N

conte

nt

(kg N

ha

-1)

0

50

100

150

200

250

300

350

Cover crop benefits

Enhanced crop yields (especially corn)

Capture and release of N to the following crop

Reduced surface runoff

Improved saturated hydraulic conductivity

Increased C and N returns to soil

Reduced nitrate leaching losses

Also note the sizeable benefit of crop rotations

in general vs. continuous cropping.

Appreciation is expressed to the organization which

helped to fund this research including the AAFC SAGES

and Green plan Programs

To: Dr. Tom Oloya, John Goerzen, Steve Burtt, Scott

Patterson, Joann Gignac for their expert technical

assistance.

Acknowledgements

Future Research

Study 1: Rotations with/without red clover

• Crop yields & N uptake

• Soil organic carbon (SOC)

• Inorganic N leaching/recovery

New Cover Crop Study (2) Objectives

To determine:

1) Crop yields and quality.

2) Soil physical quality (soil strength/hardness, soil water storage

and transmission, soil aeration, soil physical quality index

values);

3) SOC & SON amounts, types and profile distributions;

4) Nitrate leaching in the soil profile;

5) Reductions in synthetic fertilizer requirements;

New Cover Crop Study (2)

Control - No cover crop

Single Species

• Nitro radish (NR)

• Sesbania (SE)

• Phacelia (PH)

• Red clover (RC)

Mixtures

• Nitro radish + phacelia

• Nitro radish + sesbania

• Phacelia + red clover

• Nitro radish + sesbania + phacelia + red clover