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Cover Crops and Fertility- What the Research Shows
Bill Deen1, Ken Janovicek1, Henk Wichers and Greg Stewart2, 1 University of Guelph, Department of Plant Agriculture2 Ontario Ministry of Agriculture, Food and Rural Affairs
4th Annual MCCC Workshop/MeetingWindsor, Ontario February 10-11, 2009
IntroductionLimited use of cover crops in corn/soybean/ winter wheat rotations in OntarioDeclining use of red clover as an underseedin winter wheat Use of cover crops is encouraged in Ontario following summer applied manure because it is assumed that:
potential for loss of nitrogen via leaching and/or denitrification during the fall and winter period is reducedmanure credit to next year’s crop is increased.
Cover Crop/Manure Trial• 29 on-farm sites in southern
Ontario from 2003-2007. • Strip block design • Minimum 2 replicates• Cover crops:
– Oat– Oilseed radish – Field pea– Control
• Two manure rates– Farmers “typical” manure rate– No manure
• Manure applied following wheat harvest in August
Rate NH4+-N Total-N pH P2O5 K2O
kl / Mg ha-1 kg N ha-1 kg N ha-1 ppm ppmLiquid Cattle 5 5 74.3 125 234 6.8 34 124Liquid Hog 11 8 46.4 139 185 7.1 38 146Solid Cattle 7 4 48.3 61 304 7.3 26 142Solid Poultry 7 5 10.3 56 283 7.2 39 150
Manure Properties Soil PropertiesManure Type Sites Corn Sites
Summary of type of manure applied, average application rates and manure-N applied and soil fertility in surface 15cm.
• 22 sites evaluated for corn yield response
• All plots received the cooperator’s starter N rate ranging from 0 to 30 kg-N ha-1
• Cover crop/manure rate plots split – no nitrogen – 150 kg-N ha-1 as sidedress
UAN.
• Measurements– Cover crop biomass– End of season cover crop biomass N content– End of season soil N content – Corn yield– MERN estimation using delta yield approach
similar to Lory and Scharf (2003)
0
500
1000
1500
2000
2500
3000
3500
Bio
mas
s (k
g ha
-1)
Oats
Weeds/Vol.
010
2030
4050
6070
80
Bio
mas
s N
(kg
ha-1
)
0
1020
3040
50
6070
80
Soi
l N (k
g ha
-1)
No Manure Manure
b
a
cc
b
a
c c
c
bb
a
No Manure ManureNo Manure Manure
Manure application and oat cover crop effect onbiomass, biomass N, and soil N
Biomass, biomass-N and soil N bars that contain the same letter are not different at the 5% level of probability. Statistical differences were identified using log(x+1) transformed data.
0
500
1000
1500
2000
2500
3000
3500
Bio
mas
s (k
g ha
-1)
Oilseed RadishOatsWeeds/Vol.
010
2030
4050
6070
80
Bio
mas
s N
(kg
ha-1
)
0
1020
3040
50
6070
80
Soi
l N (k
g ha
-1)
No Manure Manure
b
a
cc
b
a
cc
c
bb
a
No Manure ManureNo Manure Manure
b
a
b
a
cb
Biomass, biomass-N and soil N bars that contain the same letter are not different at the 5% level of probability. Statistical differences were identified using log(x+1) transformed data.
Manure application and Oilseed Radish cover crop effect on biomass, biomass N, and soil N
0
500
1000
1500
2000
2500
3000
3500
Bio
mas
s (k
g ha
-1)
Oilseed RadishOatsWeeds/Vol.
010
2030
4050
6070
80
Bio
mas
s N
(kg
ha-1
)
0
1020
3040
50
6070
80
Soi
l N (k
g ha
-1)
No Manure Manure
b
a
cc
b
a
cc
c
bb
a
No Manure ManureNo Manure Manure
b
a
b
a
cb
Biomass, biomass-N and soil N bars that contain the same letter are not different at the 5% level of probability. Statistical differences were identified using log(x+1) transformed data.
Manure application and Oilseed Radish cover crop effect on biomass, biomass N, and soil N
No Manure ManureOilseed radish 24 18Oats 28 19Weed 19 16
C:N ratioCover crop
No Manure Manure
0
500
1000
1500
2000
2500
3000
3500
Bio
mas
s (k
g ha
-1)
Peas Oats Weeds/Vol.
010
2030
4050
6070
80
Bio
mas
s N
(kg
ha-1
)
0
1020
3040
50
6070
80
Soi
l N (k
g ha
-1)
No Manure Manure
b
a
c c
b
a
c c
bbb
a
No Manure ManureNo Manure Manure
b b
b
a
c
a
Biomass, biomass-N and soil N bars that contain the same letter are not different at the 5% level of probability. Statistical differences were identified using log(x+1) transformed data.
Manure application and Field Pea cover crop effect on biomass, biomass N, and soil N
0
500
1000
1500
2000
2500
3000
3500
Bio
mas
s (k
g ha
-1)
Peas Oats Weeds/Vol.
010
2030
4050
6070
80
Bio
mas
s N
(kg
ha-1
)
0
1020
3040
50
6070
80
Soi
l N (k
g ha
-1)
No Manure Manure
b
a
c c
b
a
c c
bbb
a
No Manure ManureNo Manure Manure
b b
b
a
c
a
Biomass, biomass-N and soil N bars that contain the same letter are not different at the 5% level of probability. Statistical differences were identified using log(x+1) transformed data.
Manure application and Field Pea cover crop effect on biomass, biomass N, and soil N
No Manure ManurePeas 13 12Oats 26 19Weed 18 15
C:N ratioCover crop
6
7
8
9
10
11
12
Yie
ld (k
g ha
-1 @
15.5
%)
OatsWeeds/Vol.
`
0
20
40
60
80
100
ME
RN
(kg
N h
a-1)
No ManureManure
b
a
c
b
aa
No Manure Manure
ba
b
a aab
No ManureManure
No Nitrogen 150 kg N ha-1
Yield and MERN bars that contain the same letter are not different at the 5% level of probability.
Manure application, Oat cover crop and nitrogen effect on corn yield and MERN
6
7
8
9
10
11
12
Yie
ld (k
g ha
-1 @
15.5
%)
Oilseed radish Oats Weeds/Vol.
`
0
20
40
60
80
100
ME
RN
(kg
N h
a-1)
No ManureManure
c
a
cb
b
a
No Manure Manure
a
a
b
aa
a
No ManureManure
No Nitrogen 150 kg N ha-1
b
a
a aa
a
Yield and MERN bars that contain the same letter are not different at the 5% level of probability.
Manure application, Oilseed Radish cover crop and nitrogen effect on corn yield and MERN
6
7
8
9
10
11
12
Yie
ld (k
g ha
-1 @
15.5
%)
Peas Oats Weeds/Vol.
`
0
20
40
60
80
100
120
ME
RN
(kg
N h
a-1)
No ManureManure
c
a
bc
c
a
No Manure Manure
a
a
c
aaa
No ManureManure
No Nitrogen 150 kg N ha-1
b
a
a aa
b
Yield and MERN bars that contain the same letter are not different at the 5% level of probability.
Manure application, Field Pea cover crop and nitrogen effect on corn yield and MERN
Oilseed radish Oats Weeds/Vol.Pea Oats Weeds/Vol.
40
60
80
100
120
140
PS
NT
(kg
N h
a-1)
Oats Weeds/Vol.
No Manure Manure
bb
aba
c
No Manure Manure
c
a ababaa
No Manure Manure
a
bc
ab
cc
PSNT bars that contain the same letter are not different at the 5% level of probability.
Manure application, and cover crop effect on pre-sidedress soil nitrate
Cover Crop/Manure Trial: Conclusions
• Oat pea and oilseed radish cover crops planted following fall manure application had increased biomass, sequestered nitrogen and reduced soil nitrogen
• Oat and oilseed radish did not reduce corn nitrogen fertilizer requirements
• Field pea reduced corn nitrogen fertilizer requirements by approximately 20 kg N ha-1 when no manure was applied
What About Red Clover?
Red Clover/Manure N
-40-20
020406080
100
Red Clover-Fall Control
-40-20
020406080
100Red Clover-Spring Control
1
2
-40-20
020406080
100No Cover
LSD=27.99LSD=28.99
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
-40-20
020406080
100
-40-20
020406080
100
Red Clover-Fall Control
-40-20
020406080
100
-40-20
020406080
100Red Clover-Spring Control
1
2
-40-20
020406080
100
-40-20
020406080
100No Cover
LSD=27.99LSD=28.99
LSD=27.99LSD=28.99
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
ActualNitrate
ActualAmmonium
RelativeNitrate
RelativeAmmonium
-40-20
020406080
100Perennial Ryegrass
-40-20
020406080
100
Oilseed Radish
-40-20
020406080
100
16/9/03 6/10/03 23/10/0314/11/03 12/4/04 26/4/04 10/5/04 26/5/04 9/6/04 21/6/04 19/7/04 1/9/04 29/11/040 20
0
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100
Oats
-40-20
020406080
100
-40-20
020406080
100Perennial Ryegrass
-40-20
020406080
100
-40-20
020406080
100
Oilseed Radish
-40-20
020406080
100
-40-20
020406080
100
16/9/03 6/10/03 23/10/0314/11/03 12/4/04 26/4/04 10/5/04 26/5/04 9/6/04 21/6/04 19/7/04 1/9/04 29/11/0416/9/0316/9/03 6/10/036/10/03 23/10/0323/10/0314/11/0314/11/03 12/4/0412/4/04 26/4/0426/4/04 10/5/0410/5/04 26/5/0426/5/04 9/6/049/6/04 21/6/0421/6/04 19/7/0419/7/04 1/9/041/9/04 29/11/0429/11/040 20
0
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
100 0 200
1000 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100 0 200
1000 200
100
Oats
Impact of cover crops on PSNT soil nitrates.
Serran, 2006
Red clover effects on N credit, yield and profit of conventional-till corn1
Corn Price2 N Cost MERN 3 MEY 4 Profit 5
$ Mg-1 $ kg-1 kg N ha-1 kg ha-1 $ ha-1
No-Red clover 143 9454 1293Red clover 79 9886 1382Difference ** ** **No-Red clover 129 9338 823Red clover 74 9841 889Difference ** ** **No-Red clover 129 9338 1234Red clover 74 9841 1353Difference ** ** **No-Red clover 107 9068 773Red clover 63 9713 863Difference ** ** **
2 Corn price after drying, handling and marketing3 Maximum economic rate of nitrogen calculated using a quadratic function4 Maximum economic yield at MERN5 Profit based on nitrogen rate and corn yield at MERN and clover establishment cost of $40 ha-1
1 Analysis conducted using 19 paired comparison of red clover-no-red clover
150 1.5
100 1.5
Cover crop
150 1
100 1
Poor red clover stands
y = -0.0108x + 115.48R2 = 0.1649
0
50
100
150
200
250
0 2000 4000 6000 8000 10000
Wheat grain dry weight (kg ha-1 @ 14.5%)
Red
clo
ver d
ensi
ty (#
m-2
)
y = -0.4242x + 4830.5R2 = 0.241
0
2000
4000
6000
8000
0 2000 4000 6000 8000 10000
Wheat grain dry weight (kg ha-1 @ 14.5%)
Red
clo
ver d
ry w
eigh
t (k
g ha
-2)
Effect of wheat yield on red clover stand and returns for winter wheat, 12 Ontario locations, 2006, 2007.
– Red clover application timing/frost tolerance– Drilling versus broadcasting – Wheat row configuration – Wheat cultivar– Wheat N rate – Wheat tillage system– Light versus drought competition
Nitrogen Effect on Red Clover
040
80120
2007
20060
10
20
30
40
50
60
70
8020072006
N Rate kg N ha-1
Effect of nitrogen rate red clover density, average of 12 Ontario locations, 2006, 2007.
Red
clo
ver d
ensi
ty #
m-2
0 kg N ha-1
0
50
100
150
200
250
300
0 20 40 60 80 100 120 140 160 180 200 220
Nitrogen rate (kg N ha-1)
Ret
urn
to N
itrog
en ($
ha-1
)$0 to -$25 ha-1
o f MERN
MERN = 102 kg ha-1
Effect of nitrogen rate on returns for winter wheat, average of 12 Ontario locations, 2006, 2007. (N @ 1.00 $Cdn kg-1, wheat @ 114 $Cdn t-1)
Tillage Effect on Red Clover
Poor red clover stands – Variable N Application?Key questions: • What is the relationship between NDVI and N credit?• What is the correlation between RC biomass and nitrogen credit?
0
50
100
150
200
250
300
0 20 40 60 80 100 120 140 160 180 200 220
Nitrogen Rate (kg-N ha-1)
Ret
urn
to N
itrog
en ($
ha-1
) Corn following red clover (MERN = 99 kg N/ha) Corn (MERN = 150 kg N/ha)
$0 to -$25 ha-1 of MERN
$0 to -$25 ha-1 of MERN
Need for N credit accuracy?
Effect of nitrogen rate on returns for corn, average of 19 pair-wise comparisons between 1990-99. (N @ 1.00 $Cdn kg-1, corn @ 100 $Cdn t-1)
