Carbon dioxide and Ozone changes and their influence on

soybean root production: an experiment conducted in open

field conditions.

Verónica Rodríguez

OUTLINEIntroduction

Atmospheric changes

Research importance

Experimental conditions

FACE experiments

Root extraction methodology

Results

Carbon sequestration

Conclusions

Open Field Vrs Controlled Environment Experiments

Open Field Vrs Controlled Environment Experiments

CO2 liquid

Tank

Vaporizers

N

S

W E

m/s5

0

10

[CO2]

Fan House

N

S

CO2

Fiber optics

CO2 liquid

Tank

Vaporizers

N

S

W E

m/s5

0

10

[CO2]

Fan House

N

S

CO2

Fiber optics

CO2 liquid

Tank

Vaporizers

N

S

W E

m/s5

0

10

[CO2]

Fan House

N

S

CO2

Fiber optics

UI FACE Experiment

FACE Research• aspen (Populus

tremuloides) • birch (Betula papyrifera) • bog • castor bean (Ricinus

communis) • chaparral • clover (Trifolium repens) • cotton (Gossypium

hirsutum) • desert • grape (Vitis vinifera) • grassland • maple (Acer saccharum) • millet (Setaria italica) • mungbean (Vigna)

• pine (Pinus taeda) • poplar (Populus) • potato (Solanum

tuberosum) • rapeseed mustard

(Brassica) • rice (Oryza) • ryegrass (Lolium perenne) • sorghum (Sorghum) • soybean (Glycine max) • sweetgum (Liquidambar

styraciflua) • temperate forest • treeline ecotone • tropical rain forest • wheat (Triticum aestivum)

Root Processing Protocol

Soil Excavation

Root Extraction

Root Sampling

ARGON

Dry procedure And Storage

Results

37.5 cm

Plant rows

Soil Excavation

37.5

50

4

5

0

12.5

2525

12.5

37.5

cm

12 2

3

Root Extraction

25 38 51 80 1080

50

100

150

200

51 80 108

50

100

150

200

a

aa

ba

b

aab

b

Elevated CO2

ControlElevated O3

Fig 5. Soybean root dry weight biomass per m2 at 25 cm depth from elevated CO2, control and elevated O3 treatments. Significance levels * P0.05, ** P0.01, **** P0.0001

Days After Planting

g/m2

*

****

**

25 38 51 80 108

0

10000

20000

30000

40000

***

***

25 38 51 80 108

0

10

20

30

40

*

Fig 6. (a) Number and (b) weight of nodules per m2 at 25 cm depth from elevated CO2 and control treatments. Significance levels * P0.05, ** P0.01, *** P0.001.

Days After Planting

Nodules number / m2 Nodules weight g/ m2

Root Soybean Distribution in the soil profile

% of Root Biomass

0 20 40 60 80

37.5 - 50

25 - 37.5

12.5 - 25

0 - 12.5 68%

13%

10%

9%

Depth

Carbon Sequestration by soilsImportance: Soil Organic carbon is the largest reservoir of carbon in the terrestrial biosphere

Why it is difficult to measure?

Importance on CO2 increased environment:

More carbon input into the soil (root and litter deposition)

But, Soil microbial activity is also increased, returning more CO2 to the atmosphere

Findings

Soil Organic Carbon Pool on soils

Soil Organic Carbon Pool on soils

Annual Organic carbon additionAnnual Organic carbon addition

CO2 additional effects extremely

difficult to measure! Elevated CO2Ambient

Other Environment interaction

FindingsCO2 increase total root biomass

Increases CO2 stability in soils (Cardon ZG, et al. 2001)

When nitrogen was non-limiting, significant increases in soil organic carbon have occurred under FACE conditions (Kimball BA, et al. 2002)

Decompositions rates on soils are not likely to change (Vuuren V, et al. 2000)

ConclusionsSoybean root plants are going to have positive feedbacks from an increase of CO2

Soybean roots are going to have little or nothing negative effects from an increase of tropospheric O3

Nodules number and weight are going to increase under elevated CO2 conditions (increases nitrogen fixation by legumes?)

Carbon soil storage is likely to increase under elevated CO2 conditions but…

It is need more experiments considering other environmental factors (temperature, water availability…)

Thank you!!

Questions?

ReferencesCardon ZG, Hungate BA, Cambardella CA, Chapin III FS, Field CB, Holland EA, Money HA. 2001. Contrasting effects of elevated CO2 on old and new soil carbon pools. Soil Biology and Biochemestry 33:365-373.

Kimball BA, Kobayashi K, Bindi M. 2002. Responses of agricultural crops to free-air CO2 enrichment. Advances in Agronomy 77: 293-368.

Van Vuuren MMI, Robinson D, Scrimgeour CM, Raven JA, Fitter AH. 2000. Decomposition of 13C-labelled wheat root systems following growth at different CO2 concentrations. Soil biology and Biochemestry 32:403-413.

Rodriguez VV, Wander M, Matamala R, Long S. 2003. Carbon dioxide and Ozone changes and their influence on soybean root production: an experiment conducted in open field conditions. Non published yet>>>

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