Carbon dioxide and Ozone changes and their influence on soybean root production: an experiment conducted in open field conditions. Verónica Rodríguez

OUTLINE Introduction Atmospheric changes Research importance Experimental conditions FACE experiments Root extraction methodology Results Carbon sequestration Conclusions

Open Field Vrs Controlled Environment Experiments

CO 2 liquid Tank Vaporizers N S W E m/s [CO 2 ] Fan House N S CO 2 Fiber optics

CO 2 liquid Tank Vaporizers N S W E m/s [CO 2 ] Fan House N S CO 2 Fiber optics

CO 2 liquid Tank Vaporizers N S W E m/s [CO 2 ] Fan House N S CO 2 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

cm 122 3

Root Extraction

Elevated CO 2 Control Elevated O 3 Fig 5. Soybean root dry weight biomass per m 2 at 25 cm depth from elevated CO 2, control and elevated O 3 treatments. Significance levels * P  0.05, ** P  0.01, **** P  Days After Planting g/m 2 * **** **

Fig 6. (a) Number and (b) weight of nodules per m 2 at 25 cm depth from elevated CO 2 and control treatments. Significance levels * P  0.05, ** P  0.01, *** P  Days After Planting Nodules number / m 2 Nodules weight g/ m 2

Carbon Sequestration by soils Importance: Soil Organic carbon is the largest reservoir of carbon in the terrestrial biosphere Why it is difficult to measure? Importance on CO 2 increased environment: More carbon input into the soil (root and litter deposition) But, Soil microbial activity is also increased, returning more CO 2 to the atmosphere Findings

Soil Organic Carbon Pool on soils Annual Organic carbon addition CO2 additional effects extremely difficult to measure! Elevated CO 2 Ambient Other Environment interaction

Findings CO 2 increase total root biomass Increases CO 2 stability in soils (Cardon ZG, et al. 2001) (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) (Kimball BA, et al. 2002) Decompositions rates on soils are not likely to change (Vuuren V, et al. 2000) (Vuuren V, et al. 2000)

Conclusions Soybean root plants are going to have positive feedbacks from an increase of CO 2 Soybean roots are going to have little or nothing negative effects from an increase of tropospheric O 3 Nodules number and weight are going to increase under elevated CO 2 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?

References Cardon ZG, Hungate BA, Cambardella CA, Chapin III FS, Field CB, Holland EA, Money HA Contrasting effects of elevated CO2 on old and new soil carbon pools. Soil Biology and Biochemestry 33: Kimball BA, Kobayashi K, Bindi M Responses of agricultural crops to free-air CO2 enrichment. Advances in Agronomy 77: Van Vuuren MMI, Robinson D, Scrimgeour CM, Raven JA, Fitter AH Decomposition of 13C-labelled wheat root systems following growth at different CO2 concentrations. Soil biology and Biochemestry 32: Rodriguez VV, Wander M, Matamala R, Long S 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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