@inproceedings{fdi:010095081,
  title = {{C}ontribution of inorganic carbon to {CO}2 emissions under a {M}editerranean agroforestry system [r{\'e}sum{\'e}]},
  author = {{C}hevallier, {T}iphaine and {C}ardinael, {R}. and {G}uenet, {B}. and {C}ozzi, {T}. and {G}irardin, {C}. and {C}henu, {C}},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n the last years, soil organic carbon ({SOC}) dynamics have been explored for agronomic and environmental issues in different agro systems. {M}any soils of the world, especially in arid and semi-arid environments, contain large stocks of soil inorganic carbon ({SIC}) as carbonates. {Y}et, the {SOC} dynamics has been poorly investigated in these soils, due to the complexity of measurements and of the processes involved. {I}ndeed, few previous studies have shown links between {SIC} and {SOC} dynamics. {T}heses interactions are initiated by biological activities, i.e. {CO}2 production, are explained through equilibrium equations between soil carbonates and bicarbonates. {H}owever, few data were available on the specific impact of {SIC} on {SOC} mineralization especially at increasing soil depth. {A}lley agroforestry systems increased {SOC} content in the tree rows without any change in the {SIC} content.  {T}he heterogeneity in organic inputs and {SOC} contents induced by alley agroforestry allows the investigation of the interactions between {SIC} and {SOC} on {CO}2 emissions. {T}o assess contributions of {SIC} to {CO}2 emissions with depth, we incubated carbonaceous soil samples coming from an 18-year-old agroforestry system (both tree row and alley) and an adjacent agricultural plot. {S}oil samples were taken at four different depths: 0-10, 10-30, 70-100 and 160-180 cm. {T}otal {CO}2 emissions, the isotopic composition (?13{C}, ?) of the {CO}2 and microbial biomass were measured. {T}he {SIC} concentrations were from 48 to 63 g {C} kg-1 soil and the {SOC} concentrations from 4 to 17 g {C} kg-1 soil. {T}he total amounts of {CO}2 emissions from soil were correlated to {C} contents and decreased with depth (from 183-569 µg{C} g-1 soil in top soil vs 21-25 µg{C} g-1 soil in subsoil). {T}he contribution of {SIC}-derived {CO}2 was not homogenous along the soil profile. {I}t represented about 20% in the topsoil and 60% in the subsoil of the total soil {CO}2 emissions. {A}s the {SOC} content and the microbial biomass, the {SOC}-derived {CO}2 emissions were larger in the topsoil especially in the tree row compared to the alley and the agricultural plot. {T}he {SIC}-derived {CO}2 emissions were also larger in topsoil and in tree rows at 0-10 cm than in alleys or agricultural plots (71 µg {C} g-1 soil vs 45-48 µg {C} g-1 soil) or in the subsoil (13-15 µg {C} g-1 soil), whereas the amount of {SIC} was similar in top and subsoil and in tree rows, alleys or agricultural soils. {T}his indicate that {CO}2 emissions from {SIC} were linked to the {SOC} content and its mineralization.  {I}n addition, our results suggest that the measurement of soil respiration in calcareous soils could be overestimated if the isotopic signature of the {CO}2 is not taken into account. {I}t also advocates more in-depth studies on carbonate dissolution-precipitation processes and their impact on {CO}2 emissions.},
  keywords = {{MEDITERRANEE}},
  numero = {},
  pages = {{EGU}2020--10139 [1 ]},
  booktitle = {},
  year = {2020},
  DOI = {10.5194/egusphere-egu2020-10139},
  URL = {https://www.documentation.ird.fr/hor/fdi:010095081},
}