yield-scaled n2o emissions in pastures:effect of earthworms and fertilizer additon
TRANSCRIPT
Yield-scaled N2O emissions in pastures: effect of earthworm (EW) activity and
fertilizer (F) addition Sebastian Yanore MSc. Thesis, end colloquium 29-03-2016
Supervisors: Ingrid Lubbers, Jan Willem van Groenigen
N2O emissions
Potent greenhouse gas Ozone depleting substance 70% emitted from agricultural activities (UNEP,
2013) 21% of agricultural lands in Europe is used for
grassland production 18% of N2O emissions in Europe comes from
pasture lands
NO3- N2NO2
- NO
NH3 NH4+ NH2OH NO2
- NO3-Nitrification
Denitrification
(Nitrifier Denitrification)
N2O
N2O
(Wrage et al.,2004)
How is N2O formed in soil?
Oxygen
Soil structure
N2OSubstrateAvailabilit
y(N,C)
Soil mesofaun
aeg EW
Moisture content
(Porre et al., 2015)
Factors controlling N2O formation in soil?
• It describes the N2O efficiency of a cropping system
Yield-scaled N2O emissions
(Van Groenigen et al., 2010)
What is known?
What is known?
What is known?
What is known?
What is known?
How EW increase N2O emissions
How EW increase crop production
What is known?
How EW activity affects the amount of N2O emitted per unit dry matter of a pasture system
How EW density affects yield-scaled N2O emissions of different pasture systems
How fertilizer addition changes the effect of EW on the amount of N2O emissions per unit dry matter of a pasture system
What is not known?
H1: EW presence increases yield-scaled N2O emission of clover, has no effect on yield-scaled N2O emission of grass, and increases slightly the yield-scaled N2O of the mixed pasture
Hypotheses
Yield
Yield
N2O
Grass, YSE =
Mixture, YSE=
Clover, YSE=
YSE =
H2: Higher EW density increases crop yield, but does not affect N2O emissions, and thus lower yield-scaled N2O emissions for the three different pastures in an order grass-mixture-clover
Hypotheses
H3: Addition of fertilizer increases the effects of EW on yield-scaled N2O emissions of all three pastures
Hypotheses
Experiment
60 days greenhouse experiment Intact soil columns Steam sterilized once at 700C for 3.5
hrs Normal EW density: 175 individuals
m-2
High EW density: 350 individuals m-2
(Didden,2010)
Experiment Fertilization: Mixture of farm yard
manure and composted fodder at ~25 kg N kg ha-1 yr-1
Trifolium repens (clover) at 6 kg ha-1
Lolium perenne (grass) at 45 kg ha-1
Clover-grass mixture at 3 and 23 kg ha-1 Starter gift: cow manure grains at 45 kg
N kg ha-1 yr-1
TreatmentsTreatment code
EW additions
Fertilization
Replicates
Control No No 5EN Normal No 5EH High No 5F No Yes 5FEN Normal Yes 5
In total: 5 treatments × 3 plant community × 5 reps = 75 columns Completely randomised into 5 blocks
N2O fluxes 25 times in 60 days Biomass harvest
Three cuts Moisture content with TDR Soil sampling with auger Destructive sampling: EW, soil
samples
Measurements
Clover Grass Mixture0
5
10
15
20
25
Cum
ulat
ive
N2O
-N e
mis
sion
(m
g N
2O-N
m
-2)
a
b
a
Results: cumulative N2O emission of pasture systems
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Clover Grass Mixture
0
5
10
15
20
25
30
35
40
Cum
ulat
ive
N2O
-N e
mis
sion
(m
g N
2O-
N m
-2)
Treatments effect on cumulative N2O emission
Results
Clover Grass Mixture0
2
4
6
8
10
12
14
16
Yiel
d (g
m-2
) a
b b
Yield(DM) of pasture systems
Results
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Clover Grass Mixture
0
2
4
6
8
10
12
14
16
18
Yiel
d (g
m-2
)Treatments effect on yield(DM)
Results
Clover Grass Mixture0
0.5
1
1.5
2
2.5
3
3.5
Yiel
d-sc
aled
N2O
-N e
mis
sion
s (m
g N
2O-N
g-
1)
a a
b
Yield-scaled N2O emission
Results
Treatments effect on yield-scaled N2O emission
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Cont
rol
EH EN
F
FEN
Clover Grass Mixture
0
1
2
3
4
5
6
Yiel
d-sc
aled
N2O
-N e
mis
sion
s (
mg
N2O
-N g
-1)
Results
R = +0.64, P < 0.001
Results
Water filled pore space (%WFPS)
R = -0.79P < 0.001
Results
Water filled pore space (%WFPS)
R = + 0.67 P < 0.001
Results
Water filled pore space (%WFPS)
H1: EW presence increases yield–scaled N2O emission of clover, has no effect on yield–scaled N2O emission of grass, and increases slightly the yield-scaled N2O emission of the mixed pasture
Borten et.al., 2000, Rizhiya et.al., 2007
✓✗✗
Cont
rol
EH ENF
FEN
Cont
rol
EH ENF
FEN
Cont
rol
EH ENF
FEN
Clover Grass Mixture
0
1
2
3
4
5
6
Yiel
d-sc
aled
N2O
-N e
mis
sion
s (m
g N
2O-N
g-1
)
Results and discussion
Cont
rol
EH ENF
FEN
Cont
rol
EH ENF
FEN
Cont
rol
EH ENF
FEN
Clover Grass Mixture
0
1
2
3
4
5
6
Yiel
d-sc
aled
N2O
-N e
mis
sion
s (m
g N
2O-N
g-1
)✗ H2: Higher EW density
increases crop yield, but does not affect N2O emissions, and thus lower yield-scaled N2O emissions for the three different pastures in an order grass-mixture-clover
Results and discussion
H3: Addition of fertilizer increases the effects of EW on yield-scaled N2O emissions of all three pastures
~25 kg N kg ha-1 yr-1
✗Co
ntro
lEH EN
FFE
NCo
ntro
lEH EN
FFE
NCo
ntro
lEH EN
FFE
N
Clover Grass Mixture
0
1
2
3
4
5
6
Yiel
d-sc
aled
N2O
-N e
mis
sion
s (m
g N
2O-N
g-1
)
Results and discussion
As simulated rainfall was constant for all treatments and clover establishment was slow due to sterilization-induced growth inhibition, %WFPS was significantly higher in the clover monocultures
We conclude that neither earthworm activity nor composted manure addition nor their interaction were determinants of yield-scaled N2O emission
Instead, in our experiment increased %WFPS was the driving factor for yield-scaled N2O emissions
Conclusions
A long(er) duration in the field At least one month after sterilization before
seeding Establishment of clover before grass in the a
mixed pasture system
Research recommendations
My supervisors: Ingrid Lubbers and Jan Willem van Groenigen
Gerlinde De Deyn CBLB André Maassen and John van
der Lippe
Acknowledgements
Thank You!