Carbon sequestration in
pasture and forage systems
A. Moulin, P. McCaughey, D. McCartney,
S. Bittman, M. Entz, W.F. Nuttall
Carbon sequestration in
rotations with forages and
pastures
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Background
Objectives
Methods
Carbon sequestration in rotations
with forages
• Carbon sequestration in fertilized and
unfertilized pasture systems
Definitions
• Greenhouse gases: nitrous oxide (N2O),
methane (CH4), carbon dioxide (CO2)
• Carbon Sequestration: Carbon stored in
the soil as soil organic matter
• Carbon Storage: Carbon stored in the soil
as plant debris, roots, and soil organic
matter
• One tonne of carbon removes 3.667
tonnes of CO2
Carbon Sequestration in forages
• Increases of 5.4 and 9.3 Mg ha-1 in
soil organic carbon (SOC) over 27
years for two studies in smooth
bromegrass grassland.
(Malhi et al. 1997, Nyborg et al 1994,
1998)
• 1.2 to 2.0 Mg C ha-1 yr -1 were stored
on soils with poor fertility
• 0.2 Mg C ha-1 yr -1 over 20 years for
intensive management of grassland.
(Agro.Manger Sept 99 p 7-8)
(Bruce et al 1999)
Objective
• To report organic carbon sequestered
in pasture systems and rotations with
forages.
• Discuss issues related to carbon
sequestration in forage systems and
pastures
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Rotation
Forages
Sink
Drain
Soil
Atmosphere
Management
Tillage
Residue
Annual Cropping Systems
• Comparison of zero and conventional
tillage at 200 locations in the Brown,
Dark Brown, and Black soils in
Saskatchewan
• Approximately 150 sites with a field
comparison, 45 replicated studies, 5
detailed studies
Current Estimates of Carbon
Sequestration
• Published literature for zero vs
conventional tillage indicates 0.2 Mg
C ha-1 yr-1 over 15 years for
agricultural soils
• Research shows higher levels
possible for Black soils over 15 years
Annual Crops (15 years)
Texture
No-till vs
Continuous
Conventional
crop from
(Mg C ha -1 yr-1)
CropFallow
-1
(Mg C ha
-1
yr )
Coarse (sand)
0.2
0.5-0.6
Medium
(loam)
0.3
0.5-0.6
Fine (clay)
0.4
0.5-0.6
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Rotation
Forages
Sink
Drain
Soil
Atmosphere
Management
Tillage
Forage Studies
• Forages in Rotation
• Melfort, Saskatchewan
• Glenlea, Manitoba
• Pasture Systems
• Pathlow, Saskatchewan
• Brandon, Manitoba
Melfort Rotations
• Established in 1957 at Melfort,
Saskatchewan
• Silty clay soil, Thick Black soils
• Fertilized and unfertilized FallowWheat-Wheat-Brome Alfalfa HayBrome Alfalfa Hay-Wheat
Soil Organic Carbon (Mg ha-1 )
250
200
150
100
50
0
1970
1978
1982
1986
1994
1970
1978
1982
1986
1994
H6
H6
H6
H6
H6
Hu6
Hu6
Hu6
Hu6
Hu6
Rotation
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Rotation
Forages
Sink
Soil
Drain
Atmosphere
Management
Glenlea Rotations
• Established in 1993 at Glenlea, Manitoba
• Clay soil, Thick Black soils
• Rotations 1) wheat-pea-wheat-flax (W-P-WFl); 2) wheat (under seeded to sweet
clover)-wheat-flax (W.Cl-W-Fl); 3) wheatalfalfa (two years)-flax (W-Al-Al-Fl); and 4)
a restored native tallgrass prairie
• Flax phase was sampled in 1999
Organic Carbon (Mgha-1)
180
160
140
120
100
80
60
40
20
0
Fertilizer
No Fertilizer
WPWF
WScWF
WAAF
Flax Phase of Rotation 1999
Native Grass
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Rotation
Forages
Sink
Soil
Drain
Atmosphere
Management
Pathlow Pasture
• Established in 1978 at Pathlow,
Saskatchewan
• Undifferentiated medium to
moderately fine textured soil, Gray
soils
• Treatments 0, 45, 90, 180 Kg ha -1 N;
0, 20 kg ha-1 P; 0, 23, 45 kg ha-1
elemental S
• Sampled in 1989 and 1999
Soil Organic Carbon (Mg ha-1 )
80
70
60
50
40
30
20
10
0
0-0-0
45-0-0
90-0-0
4-20-0
45-20-0 90-20-0 180-80-0 90-20-23 90-20-45
Fertilizer Rate (N-P-S) 1989
Soil Organic Carbon (Mg ha-1)
16
14
12
10
8
6
4
2
0
0-0-0
45-0-0
90-0-0
4-20-0
45-20-0
90-20-0
Fertilizer N-P-S 1999
180-80-0 90-20-23 90-20-45
Soil Organic Carbon (Mg ha -1)
30
25
20
15
10
5
0
0-0-0
45-0-0
90-0-0
4-20-0
45-20-0
90-20-0 180-80-0 90-20-23 90-20-45
Fertilizer Rate (N-P-S) 1999
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Sink
Soil
Drain
Atmosphere
Management
Brandon Pasture
• Established in 1994 at Brandon, Manitoba
• Fine sandy loam soil, Black soils
• Treatments fertilized and unfertilized
bromegrass, fertilized and unfertilized
alfalfa and bromegrass
• Fertilizer applied at soil test
recommendations
• Sampled in 1999
Soil Organic Carbon (Mg ha-1)
90
80
70
60
50
40
30
20
10
0
Fertilized
Unfertilized
Fertilized
Unfertilized
Alfalfabromegrass
Alfalfabromegrass
Bromegrass
Bromegrass
Rotation 1999
Carbon Sinks
Tap
Atmosphere
Management
Fertilizer
Forages
Sink
Soil
Drain
Atmosphere
Management
Carbon Sequestration in forages
• Potential carbon sequestration ranged
from 5 to 15 Mg C ha-1, over a period
from 15 to 20 years, depending on fertility
management of forages in pasture and
initial levels of soil organic carbon.