Effect of persistent subsoil compaction on N2O emissions from arable soils

(1)

EFFECT OF PERSISTENT SUBSOIL

COMPACTION ON N

₂

O EMISSIONS FROM

ARABLE SOILS

Kristiina Regina (Agrifood Research Finland)

Asko Simojoki, Laura Alakukku (University of Helsinki)

(2)

The sites

• Treatments: control and compacted

• Kävlinge: Sandy clay loam,

compacted in 1995, cereal-sugar

beet-rapeseed rotation

• Jokioinen: Clay soil, compacted in

1981, cereal cultivation

• Compaction was done using heavy

machines; effect still seen as higher

penetrometer resistance, lower air

permeability and lower gas

diffusivity in the layer 30-50 cm

• N

₂

O flux and soil air sampling

(3)

Set up

• 8 (SE) or 4 (FI) replicate

chambers and 16 sets of soil

air samplers at 15, 30, 50

and 70 cm depth in each

treatment.

• Soil moisture and

temperature loggers were

installed in some plots.

• Sampling was carried out

at 2-4 wk intervals

• No soil air sampling in

(4)

Soil

Atmosphere

NO

₃-

_N

2

NH

₄+

N

₂

O

N

₂

O

Nitrification

Modified from Davidson 1991

Regulation of N

₂

O fluxes

1) Microbial activity

3) Diffusion rate

2) Ratio of end products

Soil compaction can affect N

₂

O flux by

1) Increasing soil moisture



more denitrification



more N

₂

O

2) Decreasing aeration



less N

₂

O than N

₂

in the end products

3) Reducing diffusion from the soil



less N

₂

O flux

Denitrification

(5)

Soil moisture

Weather Lund

-20

-10

0

10

20

30 Temp (C)

0

10

20

30

40

50 Rain (mm/day

BRA TREATMENT MEAN green: 15 cm blue: 30 cm (thick line: compacted)

Jul-09 Sep Nov Jan Mar May Jul Sep Nov

0 0.1 0.2 0.3 0.4 0.5

0.6 VWC15, VWC30

BRA TREATMENT MEAN green: 15 cm blue: 30 cm (thick line: compacted)

0 0.1 0.2 0.3 0.4 0.5

0.6 VWC15, VWC30

JOK TREATMENT MEAN green: 15 cm blue: 30 cm (thick line: compacted)

0 0.1 0.2 0.3 0.4 0.5

0.6 VWC15

JOK TREATMENT MEAN green: 15 cm blue: 30 cm (thick line: compacted)

0 0.1 0.2 0.3 0.4 0.5

0.6 VWC15

Sweden

Finland

15 cm

30 cm

15 cm

(6)

O

₂

and CO

₂

in soil air - Sweden

Uncompacted = thin line, Compacted = thick line

15 cm

Jul-09Sep Nov Jan Mar May Jul Sep Nov

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

15 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

15 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

15 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

CO

₂

O

₂ 30 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

30 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

30 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

30 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

50 cm

Jul-09Sep Nov Jan Mar May Jul Sep Nov 0

50000 100000 150000

200000 O2 and CO2 (cm3/m3) 50 cm

50000 100000 150000

200000 O2 and CO2 (cm3/m3) 50 cm

50000 100000 150000

200000 O2 and CO2 (cm3/m3) 50 cm

50000 100000 150000

200000 O2 and CO2 (cm3/m3)

70 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

70 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

70 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

70 cm

0 50000 100000 150000

200000 O2 and CO2 (cm3/m3)

CO

₂

CO

₂

CO

₂

O

₂

O

₂

(7)

N

₂

O in soil air - Sweden

Uncompacted = thin line, Compacted = thick line

15 cm

0.1 1 10

100 N2O (cm3/m3)

15 cm

0.1 1 10

100 N2O (cm3/m3)

30 cm

0.1 1 10

100 N2O (cm3/m3)

30 cm

0.1 1 10

100 N2O (cm3/m3)

50 cm

Jul-09Sep Nov Jan Mar May Jul Sep Nov 0.1

1 10

100 N2O (cm3/m3) 50 cm

Jul-09Sep Nov Jan Mar May Jul Sep Nov 0.1

1 10

100 N2O (cm3/m3)

70 cm

0.1 1 10

100 N2O (cm3/m3)

70 cm

0.1 1 10

(8)

Uncompacted

Jul-09Sep Nov

Jan

Mar

May Jul

Sep

Nov

0

25

50

75

100

125

150

175

200

225 250 N2O-N g/ha/day

Compacted

Jul-09Sep Nov

Jan

Mar

May Jul

Sep

Nov

0

25

50

75

100

125

150

175

200

225 250 N2O-N g/ha/day

15 cm

Jul-09Sep Nov Jan

Mar

May Jul

Sep Nov

0.1

1

10

100 N2O (cm3/m3)

15 cm

Jul-09Sep Nov Jan

Mar

May Jul

Sep Nov

0.1

1

10

100 N2O (cm3/m3)

Error bars represent standard error of mean

(9)

N

₂

O flux, precipitation, air temperature

-Sweden

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov

P

rec

ipi

tat

ion

m

0

20

40

60

80

100

N 2

O

-N

g

h

a

-1 day

-1

-100 0 100 200 300 400

A

ir

t

em

per

at

ur

e

o C

-30 -20 -10 0 10 20 30

Precipitation N2O control N2O compacted Air temperature Temperature=0

(10)

O

₂

and CO

₂

in soil air - Finland

Uncompacted = thin line, Compacted = thick line

cm

50000 100000 150000 200000

o2 and co2 cm

50000 100000 150000 200000

o2 and co2 cm

50000 100000 150000 200000

o2 and co2 cm

50000 100000 150000 200000

o2 and co2

CO

₂

O

₂

30 cm

50000 100000 150000 200000

o2 and co2 30 cm

50000 100000 150000 200000

o2 and co2 30 cm

50000 100000 150000 200000

o2 and co2 30 cm

50000 100000 150000 200000

o2 and co2

cm

0 50000 100000 150000 200000

o2 and co2 cm

0 50000 100000 150000 200000

o2 and co2 cm

0 50000 100000 150000 200000

o2 and co2 cm

0 50000 100000 150000 200000

o2 and co2 70 cm

50000 100000 150000 200000

o2 and co2 70 cm

50000 100000 150000 200000

o2 and co2 70 cm

50000 100000 150000 200000

o2 and co2 70 cm

50000 100000 150000 200000

o2 and co2

15 cm

30 cm

50 cm

_{70 cm}

cm3_/m3

cm3_/m3 cm3_/m3

cm3_/m3

CO

₂

CO

₂

CO

₂

O

₂

_O

2

(11)

70 cm

0.3 1 3 10

100 n2o (log(y))

70 cm

0.3 1 3 10

100 n2o (log(y))

N

₂

O in soil air - Finland

Uncompacted = thin line, Compacted = thick line

m

0.3 1 3 10

100 n2o (log(y))

m

0.3 1 3 10

100 n2o (log(y))

30 cm

0.3 1 3 10

100 n2o (log(y))

30 cm

0.3 1 3 10

100 n2o (log(y))

m

0.3 1 3 10

100 n2o (log(y))

m

0.3 1 3 10

100 n2o (log(y))

15 cm

30 cm

(12)

Error bars represent standard error of mean

N

₂

O emissions and concentrations at 15 cm - Finland

Uncompacted

Jul-09Sep Nov

Jan

Mar

May Jul

Sep

Nov

0

25

50

75

100

125

150

175

200

225 250 N2O-N g/ha/day

Compacted

Jul-09Sep Nov

Jan

Mar

May Jul

Sep

Nov

0

25

50

75

100

125

150

175

200

225 250 N2O-N g/ha/day

15 cm

Jul-09Sep Nov Jan

Mar

May Jul

Sep Nov

0.3

1

3

10

100 n2o (log(y))

15 cm

Jul-09Sep Nov Jan

Mar

May Jul

Sep Nov

0.3

1

3

10

(13)

N

₂

O flux, precipitation, air temperature - Finland

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov

P

rec

ipi

tat

ion

m

0

20

40

60

80

100

N 2

O

-N

g

h

a

-1 day

-1

0 100 200 300 400

A

ir

t

em

per

at

ur

e

o C

-30 -20 -10 0 10 20 30

2009 2010

(14)

Correlation of N

₂

O flux with

soil concentrations of N

₂

O or O

₂

Sweden Finland

soilN2O_15 cm 0.51433 0.67173

<.0001 <.0001

soilN2O_30cm 0.37505 0.70759

<.0001 <.0001

soilN2O_50cm 0.52394 0.60144

<.0001 <.0001

soilN2O_70cm 0.42777 0.49448

<.0001 <.0001

soilO2_15 cm 0.05764 -0.18579

0.4117 0.0531

soilO2_30cm 0.13658 -0.19226

0.0532 0.0462

soilO2_50cm 0.06406 -0.41546

0.3638 <.0001

soilO2_70cm 0.07765 -0.52309

(15)

Annual fluxes

N₂O-N ha-1 year-1

0 2 4 6 8 10 12 14 16

Finland compacted Finland control Sweden compacted Sweden control

(16)

Conclusions

• Compaction occasionally increased N

₂

O in soil air.

• No large differences in soil air composition, N

₂

O emissions or

moisture content were found between the treatments.

• The N

₂

O concentrations at 15, 30, 50 and 70 cm depths correlated

positively with the emission of N

₂

O from the soil in both fields

(r = 0.4-0.7

***

_).

• The subsoil O

₂

concentrations correlated negatively with N

₂

O

emission, but only at the Finnish site.

• The results suggest that subsoil compaction does not significantly

(17)