Soil and vegetation-atmosphere exchange of NO, NH3, and N2O from field measurements in a semi arid grazed ecosystem in Senegal

C. Delon; C. Galy-Lacaux; D. Serça; B. Loubet; N. Camara; E. Gardrat; I. Saneh; Rasmus Fensholt; Håkan Torbern Tagesson; V. Le Dantec; B. Sambou; C. Diop; E. Mougin

doi:10.1016/j.atmosenv.2017.02.024

Soil and vegetation-atmosphere exchange of NO, NH₃, and N₂O from field measurements in a semi arid grazed ecosystem in Senegal

C. Delon^*, C. Galy-Lacaux, D. Serça, B. Loubet, N. Camara, E. Gardrat, I. Saneh, Rasmus Fensholt, Håkan Torbern Tagesson, V. Le Dantec, B. Sambou, C. Diop, E. Mougin

^*Corresponding author for this work

Geography

9 Citations (Scopus)

Abstract

The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH₃. The ammonia compensation point in the soil ranged between 7 and 150 ppb, with soil temperatures between 32 and 37 °C. Ammonia exchange fluctuated between emission and deposition (from −0.1–1.3 ng N.m⁻² s⁻¹), depending on meteorology, ambient NH₃ concentration (5–11 ppb) and compensation point mixing ratios. N₂O fluxes are supposed to be lower than NO fluxes in semi arid ecosystems, but in Dahra N₂O fluxes (5.5 ± 1.3 ng N m⁻² s⁻¹ in July 2013, and 3.2 ± 1.7 ng N m⁻² s⁻¹ in November 2013) were similar to NO fluxes (5.7 ± 3.1 ng N m⁻² s⁻¹ in July 2012, 5.1 ± 2.1 ng N m⁻² s⁻¹ in July 2013, and 4.0 ± 2.2 ngN m⁻² s⁻¹ in November 2013). Possible reasons are the influence of soil moisture below the surface (where N₂O is produced) after the beginning of the wet season, the potential aerobic denitrification in microsites, the nitrifier denitrification, and nitrification processes. The presence of litter and standing straw, and their decomposition dominated N compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO₂ respiration fluxes were high in the beginning (107 ± 26 mg m⁻² h⁻¹ in July 2013) and low in the end of the wet season (32 ± 5 mg m⁻² h⁻¹ in November 2013), when autotrophic and heterotrophic activity is reduced due to low soil moisture conditions These results confirm that contrasted ecosystem conditions due to drastic changes in water availability in semi arid regions have important non linear impacts on the biogeochemical nitrogen cycle.

Original language	English
Journal	Atmospheric Environment
Volume	156
Pages (from-to)	36-51
Number of pages	16
ISSN	1352-2310
DOIs	https://doi.org/10.1016/j.atmosenv.2017.02.024
Publication status	Published - 2017

Keywords

Biogenic emissions
Litter emissions
Nitrogen compound exchanges
Semi arid tropical ecosystem
Soil processes of nitrogen release
Soil respiration

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10.1016/j.atmosenv.2017.02.024

Cite this

Delon, C., Galy-Lacaux, C., Serça, D., Loubet, B., Camara, N., Gardrat, E., Saneh, I., Fensholt, R., Tagesson, H. T., Le Dantec, V., Sambou, B., Diop, C., & Mougin, E. (2017). Soil and vegetation-atmosphere exchange of NO, NH₃, and N₂O from field measurements in a semi arid grazed ecosystem in Senegal. Atmospheric Environment, 156, 36-51. https://doi.org/10.1016/j.atmosenv.2017.02.024

Delon, C, Galy-Lacaux, C, Serça, D, Loubet, B, Camara, N, Gardrat, E, Saneh, I, Fensholt, R , Tagesson, HT, Le Dantec, V, Sambou, B, Diop, C & Mougin, E 2017, 'Soil and vegetation-atmosphere exchange of NO, NH₃, and N₂O from field measurements in a semi arid grazed ecosystem in Senegal', Atmospheric Environment, vol. 156, pp. 36-51. https://doi.org/10.1016/j.atmosenv.2017.02.024

@article{8cf32b254ba64d879bf7268dda998e70,

title = "Soil and vegetation-atmosphere exchange of NO, NH3, and N2O from field measurements in a semi arid grazed ecosystem in Senegal",

abstract = "The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH3. The ammonia compensation point in the soil ranged between 7 and 150 ppb, with soil temperatures between 32 and 37 °C. Ammonia exchange fluctuated between emission and deposition (from −0.1–1.3 ng N.m−2 s−1), depending on meteorology, ambient NH3 concentration (5–11 ppb) and compensation point mixing ratios. N2O fluxes are supposed to be lower than NO fluxes in semi arid ecosystems, but in Dahra N2O fluxes (5.5 ± 1.3 ng N m−2 s−1 in July 2013, and 3.2 ± 1.7 ng N m−2 s−1 in November 2013) were similar to NO fluxes (5.7 ± 3.1 ng N m−2 s−1 in July 2012, 5.1 ± 2.1 ng N m−2 s−1 in July 2013, and 4.0 ± 2.2 ngN m−2 s−1 in November 2013). Possible reasons are the influence of soil moisture below the surface (where N2O is produced) after the beginning of the wet season, the potential aerobic denitrification in microsites, the nitrifier denitrification, and nitrification processes. The presence of litter and standing straw, and their decomposition dominated N compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO2 respiration fluxes were high in the beginning (107 ± 26 mg m−2 h−1 in July 2013) and low in the end of the wet season (32 ± 5 mg m−2 h−1 in November 2013), when autotrophic and heterotrophic activity is reduced due to low soil moisture conditions These results confirm that contrasted ecosystem conditions due to drastic changes in water availability in semi arid regions have important non linear impacts on the biogeochemical nitrogen cycle.",

keywords = "Biogenic emissions, Litter emissions, Nitrogen compound exchanges, Semi arid tropical ecosystem, Soil processes of nitrogen release, Soil respiration",

author = "C. Delon and C. Galy-Lacaux and D. Ser{\c c}a and B. Loubet and N. Camara and E. Gardrat and I. Saneh and Rasmus Fensholt and Tagesson, {H{\aa}kan Torbern} and {Le Dantec}, V. and B. Sambou and C. Diop and E. Mougin",

year = "2017",

doi = "10.1016/j.atmosenv.2017.02.024",

language = "English",

volume = "156",

pages = "36--51",

journal = "Atmospheric Environment",

issn = "1352-2310",

publisher = "Pergamon Press",

}

TY - JOUR

T1 - Soil and vegetation-atmosphere exchange of NO, NH3, and N2O from field measurements in a semi arid grazed ecosystem in Senegal

AU - Delon, C.

AU - Galy-Lacaux, C.

AU - Serça, D.

AU - Loubet, B.

AU - Camara, N.

AU - Gardrat, E.

AU - Saneh, I.

AU - Fensholt, Rasmus

AU - Tagesson, Håkan Torbern

AU - Le Dantec, V.

AU - Sambou, B.

AU - Diop, C.

AU - Mougin, E.

PY - 2017

Y1 - 2017

N2 - The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH3. The ammonia compensation point in the soil ranged between 7 and 150 ppb, with soil temperatures between 32 and 37 °C. Ammonia exchange fluctuated between emission and deposition (from −0.1–1.3 ng N.m−2 s−1), depending on meteorology, ambient NH3 concentration (5–11 ppb) and compensation point mixing ratios. N2O fluxes are supposed to be lower than NO fluxes in semi arid ecosystems, but in Dahra N2O fluxes (5.5 ± 1.3 ng N m−2 s−1 in July 2013, and 3.2 ± 1.7 ng N m−2 s−1 in November 2013) were similar to NO fluxes (5.7 ± 3.1 ng N m−2 s−1 in July 2012, 5.1 ± 2.1 ng N m−2 s−1 in July 2013, and 4.0 ± 2.2 ngN m−2 s−1 in November 2013). Possible reasons are the influence of soil moisture below the surface (where N2O is produced) after the beginning of the wet season, the potential aerobic denitrification in microsites, the nitrifier denitrification, and nitrification processes. The presence of litter and standing straw, and their decomposition dominated N compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO2 respiration fluxes were high in the beginning (107 ± 26 mg m−2 h−1 in July 2013) and low in the end of the wet season (32 ± 5 mg m−2 h−1 in November 2013), when autotrophic and heterotrophic activity is reduced due to low soil moisture conditions These results confirm that contrasted ecosystem conditions due to drastic changes in water availability in semi arid regions have important non linear impacts on the biogeochemical nitrogen cycle.

AB - The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH3. The ammonia compensation point in the soil ranged between 7 and 150 ppb, with soil temperatures between 32 and 37 °C. Ammonia exchange fluctuated between emission and deposition (from −0.1–1.3 ng N.m−2 s−1), depending on meteorology, ambient NH3 concentration (5–11 ppb) and compensation point mixing ratios. N2O fluxes are supposed to be lower than NO fluxes in semi arid ecosystems, but in Dahra N2O fluxes (5.5 ± 1.3 ng N m−2 s−1 in July 2013, and 3.2 ± 1.7 ng N m−2 s−1 in November 2013) were similar to NO fluxes (5.7 ± 3.1 ng N m−2 s−1 in July 2012, 5.1 ± 2.1 ng N m−2 s−1 in July 2013, and 4.0 ± 2.2 ngN m−2 s−1 in November 2013). Possible reasons are the influence of soil moisture below the surface (where N2O is produced) after the beginning of the wet season, the potential aerobic denitrification in microsites, the nitrifier denitrification, and nitrification processes. The presence of litter and standing straw, and their decomposition dominated N compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO2 respiration fluxes were high in the beginning (107 ± 26 mg m−2 h−1 in July 2013) and low in the end of the wet season (32 ± 5 mg m−2 h−1 in November 2013), when autotrophic and heterotrophic activity is reduced due to low soil moisture conditions These results confirm that contrasted ecosystem conditions due to drastic changes in water availability in semi arid regions have important non linear impacts on the biogeochemical nitrogen cycle.

KW - Biogenic emissions

KW - Litter emissions

KW - Nitrogen compound exchanges

KW - Semi arid tropical ecosystem

KW - Soil processes of nitrogen release

KW - Soil respiration

U2 - 10.1016/j.atmosenv.2017.02.024

DO - 10.1016/j.atmosenv.2017.02.024

M3 - Journal article

AN - SCOPUS:85013378469

SN - 1352-2310

VL - 156

SP - 36

EP - 51

JO - Atmospheric Environment

JF - Atmospheric Environment