Research Article
BibTex RIS Cite
Year 2021, Volume: 10 Issue: 1, 51 - 60, 01.01.2021
https://doi.org/10.18393/ejss.809272

Abstract

References

  • AFNOR, 1994. Qualité du sol et détermination du taux d’humidité à 105°C (NF X15-110). [in French].
  • AFNOR, 1998. Qualité du sol et dosage du carbone organique par oxydation sulfochromique ou au bicarbonate de potassium (NF ISO 14235). [in French].
  • AFNOR, 2002. Qualité des sols, détermination des cations : Ca++, Mg++, K+, Na+ extractibles par l’acétate d’ammonium et méthode par agitation (NF X31-108). [in French].
  • AFNOR, 2003. Qualité du sol, détermination de la distribution granulométrique des particules du sol et méthode à la pipette (NF X31-107).
  • AFNOR, 2005. Qualité du sol et détermination du pH (NF ISO 10390). [in French].
  • AFNOR, 2006. Qualité du sol et prétraitement des échantillons pour analyses physico-chimiques (NF ISO 11464). [in French].
  • AFNOR, 2011. Qualité du sol et détermination de la capacité d’échange cationique (CEC) effective et des cations échangeables à l’aide d’une solution de trichlorure de cobaltihexammine (NF EN ISO 23470). [in French].
  • Agboadoh, D.M.Y., 2011. Soil organic carbon stocks in croplands of the Bechem Forest District, Ghana (Unpublished master’s thesis). Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
  • Alex, D., Rollin, A., 2017. Gestion de la MO et des flux de carbone en grandes cultures et prairies. 28p. [in French]. Available at [Access date: 01.05.2020]: https://agriculture-de-conservation.com/sites/agriculture-de-conservation.com/IMG/pdf/travail-phytotechnie-1m-dumoulin-rollin.pdf
  • Awé, D.V., Noiha, N.V., Zapfack, L., 2020. Carbon Storage and emission factor of Savanna ecosystems in Sudano-Sahelian zone of Cameroon. Journal of Botany Research 2(1): 60-67.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Ali, A.D., Madou, C., 2019b. Carbon stocks in dead wood biomass of Savannah ecosystems in Northern Region Cameroon. Journal of Botany Research 2(1): 60-70.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Vroh, B.T.A., Nyeck, B., 2019c. Vegetation structure, root biomass distribution and soil carbon stock of Savannah agrosystems in Sudano-Sahelian Zone of Cameroon. Journal of Botany Research 2(1): 71-80.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Vroh, B.T.A., Saïdou, A., 2019a. Carbon sequestration potential and economic value in agroforestry parkland to Tectona grandis L. f. (Verbenaceae) in Central Africa: A case study to Department of Poli (Northern Region in Cameroon). Advances in Research 18(5): 1-16.
  • Bessah, E., Bala, A., Agodzo, S.K., Okhimamhe, A.A., 2016. Dynamics of soil organic carbon stocks in the Guinea savanna and transition agro-ecology under different land-use systems in Ghana. Cogent Geoscience 2(1) : 1140319.
  • Carrier, A., 2003. Que Se Passe-t-Il Dans Le Sol?. Serriculture Maraichère Biologique. 9p. [in French]. Available at [Access date: 01.05.2020]: https://www.agrireseau.net/legumesdeserre/Documents/QUE%20SE%20PASSE-T-IL%20DANS%20SOL%20(AC)%20-%2003-03-31.PDF
  • Coudurier, C., Bourgogne, A., 2012. Guide Pédologique: Les Sols. 34p. [in French]. Available at [Access date: 01.05.2020]: https://www.alterrebourgognefranchecomte.org/_depot_alterrebourgogne/_depot_arko/basesdoc/4/14145/guide-pedago-les-sols.pdf
  • Dabin, B., 1985. Les sols tropicaux acides : Cah. ORSTOM, Série de Pédologie 21(1):7–19. [in French].
  • Dawkins, H.C., 1959. The volume increment of natural tropical high forest and limitations on its improvement. Empire Forest Review 38(2): 175-180.
  • Decoopman, B., Hanocq, D., Heddadj, D., Dibet, A., 2013. Tout Ce Que Vous Avez Toujours Voulu Savoir Sur Le Sol. TERRA. 33p. [in French]. Available at [Access date: 01.05.2020]: https://agriculture-de-conservation.com/sites/agriculture-de-conservation.com/IMG/pdf/sol-bretagne.pdf
  • Dengiz, O., Saygın, F., İmamoğlu, A., 2019. Spatial variability of soil organic carbon density under different land cover and soil types in a sub-humid terrestrial ecosystem. Eurasian Journal of Soil Science 8(1): 35 – 43.
  • FAO, 2015. Learning tool on nationally appropriate mitigation actions (NAMAs) in the agriculture, forestry and other land use (AFOLU) sector. Food and Agriculture Organization of the United Nations, Rome, Italy. 90p. Available at [Access date: 01.05.2020]: http://www.fao.org/3/a-i4642e.pdf
  • FAO, 2017a. Soil Organic Carbon: the hidden potential. Food and Agriculture Organization of the United Nations, Rome, Italy. 90p. Available at [Access date: 01.05.2020]: http://www.fao.org/3/a-i6937e.pdf
  • Gorham, C., Lavery, P., Kelleway, J.J., Salinas, C., Serrano, O., 2020. Soil Carbon Stocks Vary Across Geomorphic Settings in Australian Temperate Tidal Marsh Ecosystems. Ecosystems [in Press]
  • Hoffmann, U., Yair, A., Hikel, H., Kuhn, N.J., 2012. Soil organic carbon in the rocky desert of northern Negev (Israel). Journal of Soils and Sediments 12: 811-825.
  • İmamoğlu, A., Dengiz, O., 2016. Determination of soil erosion risk using RUSLE model and soil organic carbon loss in Alaca catchment (Central Black Sea Region, Turkey). Rendiconti Lincei 28(1): 11-23.
  • Jiao, Y., Xu, Z., Zhao, J., Yang, W., 2012. Changes in soil carbon stocks and related soil properties along a 50-year grassland-to-cropland conversion chronosequence in an agro-pastoral ecotone of Inner Mongolia, China. Journal of Arid Land 4(4): 420–430.
  • Kjeldahl, J., 1883. Neue Methode zur Bestimmung des Stickstoffs in organischen Körpern. Zeitschrift für analytische Chemie 22(1): 366-382.
  • Liu, J., Bowman, K.W., Schimel, D.S., Parazoo, N.C., Jiang, Z., Lee, M., Bloom, A.A., Wunch, D., Frankenberg, C., Sun, Y., O’Dell, C.W., Gurney, K.R., Menemenlis, D., Gierach,M., Crisp, D., Eldering, A., 2017. Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño. Science 358(5690): aam5690.
  • Mazarrasa, I., Samper-Villarreal, J., Serrano, O., Lavery, P.S., Lovelock, C.E., Marbà, N., Duarte, C.M., Cortés, J., 2018. Habitat characteristics provide insights of carbon storage in seagrass meadows. Marine Pollution Bulletin 134: 106–117.
  • Moore, B., Kaur, G., Motavalli, P., Zurweller, B., Svoma, B., 2018. Soil greenhouse gas emissions from agroforestry and other land uses under different moisture regimes in lower Missouri River Floodplain soils: a laboratory approach. Agroforestry Systems 92: 335-348.
  • Munguakonkwa, C.M., 2018. Etude de la variation de stocks de carbone dans le sol forestier suivant le type d'utilisation de terre à Tshivanga au PNKB. Mémoire d’ingénieur Agronome Option : Eaux et forêts, Université catholique de Bukavu. pp.63.
  • Nibéron, C., 2016. La Séquestration Du Carbone Dans Les Sols. France-Sciences. 4p. [in French].
  • Ontl, T.A., Schulte, L.A., 2012. Soil Carbon Storage. Nature Education Knowledge 3(10):35.
  • Ranger, J., 2018. La fertilité des sols forestiers : quels sont ses déterminants ? 4p La Forêt et le Bois en France en 100 Questions. [in French]. Available at [Access date: 01.05.2020]: https://www.academie-foret-bois.fr/app/download/15649034624/2.03.+fertilite%CC%81.pdf?t=1579071403
  • Roger, E., Rabarison, H., 2000. Contexte biologique de la conservation des forêts à Madagascar. Etude sur la politique de conservation des ressources forestières à Madagascar, 53p. [in French].
  • Rovai, A.S., Twilley, R.R., Castañeda-Moya, E., Riul, P., Cifuentes-Jara, M., Manrow-Villalobos, M., Horta, P.A., Simonassi, J.C., Fonseca, A.L., Pagliosa, P.R., 2018. Global controls on carbon storage in mangrove soils. Nature Climate Change 8: 534-538.
  • Schmidt, M.W.I., Torn, M.S., Abive, S., Dittimar, T., Guggenberger, G., Janssens, IA., Kleber, M., Kogel-Knabner, I., Lehmann, J., Manning, D.A.C., Nannipieri, P., Rasse, D.P., Weiner, S., Trumbore, S.E., 2011. Persistence of soil organic matter as an ecosystem property. Nature 478: 49-56.
  • Spohn, M., 2020. Phosphorus and carbon in soil particle size fractions: A synthesis. Biogeochemistry 147: 225–242.
  • Stahr, S., Graf-Rosenfellner, M., Klysubun, W., Mikutta, R., Prietzel, J., Lang, F., 2018. Phosphorus speciation and C:N:P stoichiometry of functional organic matter fractions in temperate forest soils. Plant and Soil 427(1–2):53–69.
  • Stockmann, U., Adams, M.A., Crawford, J.W., Field, D.J., Henakaarchchi, N., Jenkins, M., Minasny, B., McBratney, A.B., Courcelles, V.R., Singh, K., Wheeler, I., Abbott, L., Angers, D.A., Baldock, J., Bird, M., Brookes, P.C., Chenu, C., Jastrow, J.D., Lal, R., Lehmann, J.O., Donnell, A.G., Parton, W. J., Whitehead, D., Zimmermann, M., 2013. The knowns, known unknowns and unknowns of sequestration of soil organic carbon. Agriculture, Ecosystems and Environment 164: 80-99.
  • Swiderski, C., Saby, N.P.A., Party, J.P., Sauter, J., Köller, R., Vandijk, P., Lemercier, B., Arrouays, D., 2012. Evolution des teneurs en carbone organique dans l'horizon de surface des sols cultivés en Alsace : Analyse à partir de la Base de Données de Analyses de Terre. Etude et Gestion des Sols 19(3) :179-192. [in French].
  • Walkley, A., Black, C.A., 1934. An examination of Digestion method for determining soil organic matter and proposed modification of the chromic acid titration method. Soil Science 37(1): 29-38.
  • Youl, S., 2005. Dynamique et modélisation de la dynamique du carbone dans un agrosystème de savane de l'Ouest du Burkina Faso. Thèse de doctorat unique, Université Polytechnique de Bobo Dioulasso (UPS) du Burkina Faso. 144p. [in French].

Dynamics of soil organic carbon stock under different types of savannah agrosystems in the Sudano-Sahelian zone of Cameroon

Year 2021, Volume: 10 Issue: 1, 51 - 60, 01.01.2021
https://doi.org/10.18393/ejss.809272

Abstract

The aim of this study was to quantify the current soil organic carbon stock under different types of savannah agrosystems in the Sudano-Sahelian zone of Cameroon in the context of greenhouse gas emissions and land degradation. It is so crucial for combating climate change and improving ecological restoration. Random field sampling was carried out on 0-10, 10-20 and 20-30 cm depth, then were collected in four types of savannah agrosystems. Soil bulk density, pH, moisture content, CEC, exchangeable bases, particle size distribution and soil organic carbon were determined using standard laboratory procedures and calculations. The results of the study did not reveal a significant difference in soil organic carbon stock between different types of savannah agrosystems (P>0.05). Soils of Tamarindus indica savannah agrosystems in recorded higher values SCOS (36.03 ± 3.31 tC/ha), Prosopis africana (33.40 ± 3.27 tC/ha), Haematostaphis barterii (31.83 ± 3.21 tC/ha) and Detarium microcarpum (31.19 ± 3.19 tC/ha) savannah agrosystems. Similarly, SCOS decreased with soil depth in all types of savannah agrosystems. Results showed a positive and significant (P<0.05) correlation between soil organic carbon stock with basal area, biovolume, bulk density, moisture content, C/N ratio, Ca2+, Mg2+, OM; negative and significant (P<0.05) with Soil pH, Total Nitrogen, Na+ but negative and non-significant (P>0.05) with Density, K+, CEC, Sand %, Silt %, Clay %, Silt + Clay %. The results show the potential contribution of savannah agrosystems to improve soil organic carbon sequestration and environmental protection.

References

  • AFNOR, 1994. Qualité du sol et détermination du taux d’humidité à 105°C (NF X15-110). [in French].
  • AFNOR, 1998. Qualité du sol et dosage du carbone organique par oxydation sulfochromique ou au bicarbonate de potassium (NF ISO 14235). [in French].
  • AFNOR, 2002. Qualité des sols, détermination des cations : Ca++, Mg++, K+, Na+ extractibles par l’acétate d’ammonium et méthode par agitation (NF X31-108). [in French].
  • AFNOR, 2003. Qualité du sol, détermination de la distribution granulométrique des particules du sol et méthode à la pipette (NF X31-107).
  • AFNOR, 2005. Qualité du sol et détermination du pH (NF ISO 10390). [in French].
  • AFNOR, 2006. Qualité du sol et prétraitement des échantillons pour analyses physico-chimiques (NF ISO 11464). [in French].
  • AFNOR, 2011. Qualité du sol et détermination de la capacité d’échange cationique (CEC) effective et des cations échangeables à l’aide d’une solution de trichlorure de cobaltihexammine (NF EN ISO 23470). [in French].
  • Agboadoh, D.M.Y., 2011. Soil organic carbon stocks in croplands of the Bechem Forest District, Ghana (Unpublished master’s thesis). Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
  • Alex, D., Rollin, A., 2017. Gestion de la MO et des flux de carbone en grandes cultures et prairies. 28p. [in French]. Available at [Access date: 01.05.2020]: https://agriculture-de-conservation.com/sites/agriculture-de-conservation.com/IMG/pdf/travail-phytotechnie-1m-dumoulin-rollin.pdf
  • Awé, D.V., Noiha, N.V., Zapfack, L., 2020. Carbon Storage and emission factor of Savanna ecosystems in Sudano-Sahelian zone of Cameroon. Journal of Botany Research 2(1): 60-67.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Ali, A.D., Madou, C., 2019b. Carbon stocks in dead wood biomass of Savannah ecosystems in Northern Region Cameroon. Journal of Botany Research 2(1): 60-70.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Vroh, B.T.A., Nyeck, B., 2019c. Vegetation structure, root biomass distribution and soil carbon stock of Savannah agrosystems in Sudano-Sahelian Zone of Cameroon. Journal of Botany Research 2(1): 71-80.
  • Awé, D.V., Noiha, N.V., Zapfack, L., Vroh, B.T.A., Saïdou, A., 2019a. Carbon sequestration potential and economic value in agroforestry parkland to Tectona grandis L. f. (Verbenaceae) in Central Africa: A case study to Department of Poli (Northern Region in Cameroon). Advances in Research 18(5): 1-16.
  • Bessah, E., Bala, A., Agodzo, S.K., Okhimamhe, A.A., 2016. Dynamics of soil organic carbon stocks in the Guinea savanna and transition agro-ecology under different land-use systems in Ghana. Cogent Geoscience 2(1) : 1140319.
  • Carrier, A., 2003. Que Se Passe-t-Il Dans Le Sol?. Serriculture Maraichère Biologique. 9p. [in French]. Available at [Access date: 01.05.2020]: https://www.agrireseau.net/legumesdeserre/Documents/QUE%20SE%20PASSE-T-IL%20DANS%20SOL%20(AC)%20-%2003-03-31.PDF
  • Coudurier, C., Bourgogne, A., 2012. Guide Pédologique: Les Sols. 34p. [in French]. Available at [Access date: 01.05.2020]: https://www.alterrebourgognefranchecomte.org/_depot_alterrebourgogne/_depot_arko/basesdoc/4/14145/guide-pedago-les-sols.pdf
  • Dabin, B., 1985. Les sols tropicaux acides : Cah. ORSTOM, Série de Pédologie 21(1):7–19. [in French].
  • Dawkins, H.C., 1959. The volume increment of natural tropical high forest and limitations on its improvement. Empire Forest Review 38(2): 175-180.
  • Decoopman, B., Hanocq, D., Heddadj, D., Dibet, A., 2013. Tout Ce Que Vous Avez Toujours Voulu Savoir Sur Le Sol. TERRA. 33p. [in French]. Available at [Access date: 01.05.2020]: https://agriculture-de-conservation.com/sites/agriculture-de-conservation.com/IMG/pdf/sol-bretagne.pdf
  • Dengiz, O., Saygın, F., İmamoğlu, A., 2019. Spatial variability of soil organic carbon density under different land cover and soil types in a sub-humid terrestrial ecosystem. Eurasian Journal of Soil Science 8(1): 35 – 43.
  • FAO, 2015. Learning tool on nationally appropriate mitigation actions (NAMAs) in the agriculture, forestry and other land use (AFOLU) sector. Food and Agriculture Organization of the United Nations, Rome, Italy. 90p. Available at [Access date: 01.05.2020]: http://www.fao.org/3/a-i4642e.pdf
  • FAO, 2017a. Soil Organic Carbon: the hidden potential. Food and Agriculture Organization of the United Nations, Rome, Italy. 90p. Available at [Access date: 01.05.2020]: http://www.fao.org/3/a-i6937e.pdf
  • Gorham, C., Lavery, P., Kelleway, J.J., Salinas, C., Serrano, O., 2020. Soil Carbon Stocks Vary Across Geomorphic Settings in Australian Temperate Tidal Marsh Ecosystems. Ecosystems [in Press]
  • Hoffmann, U., Yair, A., Hikel, H., Kuhn, N.J., 2012. Soil organic carbon in the rocky desert of northern Negev (Israel). Journal of Soils and Sediments 12: 811-825.
  • İmamoğlu, A., Dengiz, O., 2016. Determination of soil erosion risk using RUSLE model and soil organic carbon loss in Alaca catchment (Central Black Sea Region, Turkey). Rendiconti Lincei 28(1): 11-23.
  • Jiao, Y., Xu, Z., Zhao, J., Yang, W., 2012. Changes in soil carbon stocks and related soil properties along a 50-year grassland-to-cropland conversion chronosequence in an agro-pastoral ecotone of Inner Mongolia, China. Journal of Arid Land 4(4): 420–430.
  • Kjeldahl, J., 1883. Neue Methode zur Bestimmung des Stickstoffs in organischen Körpern. Zeitschrift für analytische Chemie 22(1): 366-382.
  • Liu, J., Bowman, K.W., Schimel, D.S., Parazoo, N.C., Jiang, Z., Lee, M., Bloom, A.A., Wunch, D., Frankenberg, C., Sun, Y., O’Dell, C.W., Gurney, K.R., Menemenlis, D., Gierach,M., Crisp, D., Eldering, A., 2017. Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño. Science 358(5690): aam5690.
  • Mazarrasa, I., Samper-Villarreal, J., Serrano, O., Lavery, P.S., Lovelock, C.E., Marbà, N., Duarte, C.M., Cortés, J., 2018. Habitat characteristics provide insights of carbon storage in seagrass meadows. Marine Pollution Bulletin 134: 106–117.
  • Moore, B., Kaur, G., Motavalli, P., Zurweller, B., Svoma, B., 2018. Soil greenhouse gas emissions from agroforestry and other land uses under different moisture regimes in lower Missouri River Floodplain soils: a laboratory approach. Agroforestry Systems 92: 335-348.
  • Munguakonkwa, C.M., 2018. Etude de la variation de stocks de carbone dans le sol forestier suivant le type d'utilisation de terre à Tshivanga au PNKB. Mémoire d’ingénieur Agronome Option : Eaux et forêts, Université catholique de Bukavu. pp.63.
  • Nibéron, C., 2016. La Séquestration Du Carbone Dans Les Sols. France-Sciences. 4p. [in French].
  • Ontl, T.A., Schulte, L.A., 2012. Soil Carbon Storage. Nature Education Knowledge 3(10):35.
  • Ranger, J., 2018. La fertilité des sols forestiers : quels sont ses déterminants ? 4p La Forêt et le Bois en France en 100 Questions. [in French]. Available at [Access date: 01.05.2020]: https://www.academie-foret-bois.fr/app/download/15649034624/2.03.+fertilite%CC%81.pdf?t=1579071403
  • Roger, E., Rabarison, H., 2000. Contexte biologique de la conservation des forêts à Madagascar. Etude sur la politique de conservation des ressources forestières à Madagascar, 53p. [in French].
  • Rovai, A.S., Twilley, R.R., Castañeda-Moya, E., Riul, P., Cifuentes-Jara, M., Manrow-Villalobos, M., Horta, P.A., Simonassi, J.C., Fonseca, A.L., Pagliosa, P.R., 2018. Global controls on carbon storage in mangrove soils. Nature Climate Change 8: 534-538.
  • Schmidt, M.W.I., Torn, M.S., Abive, S., Dittimar, T., Guggenberger, G., Janssens, IA., Kleber, M., Kogel-Knabner, I., Lehmann, J., Manning, D.A.C., Nannipieri, P., Rasse, D.P., Weiner, S., Trumbore, S.E., 2011. Persistence of soil organic matter as an ecosystem property. Nature 478: 49-56.
  • Spohn, M., 2020. Phosphorus and carbon in soil particle size fractions: A synthesis. Biogeochemistry 147: 225–242.
  • Stahr, S., Graf-Rosenfellner, M., Klysubun, W., Mikutta, R., Prietzel, J., Lang, F., 2018. Phosphorus speciation and C:N:P stoichiometry of functional organic matter fractions in temperate forest soils. Plant and Soil 427(1–2):53–69.
  • Stockmann, U., Adams, M.A., Crawford, J.W., Field, D.J., Henakaarchchi, N., Jenkins, M., Minasny, B., McBratney, A.B., Courcelles, V.R., Singh, K., Wheeler, I., Abbott, L., Angers, D.A., Baldock, J., Bird, M., Brookes, P.C., Chenu, C., Jastrow, J.D., Lal, R., Lehmann, J.O., Donnell, A.G., Parton, W. J., Whitehead, D., Zimmermann, M., 2013. The knowns, known unknowns and unknowns of sequestration of soil organic carbon. Agriculture, Ecosystems and Environment 164: 80-99.
  • Swiderski, C., Saby, N.P.A., Party, J.P., Sauter, J., Köller, R., Vandijk, P., Lemercier, B., Arrouays, D., 2012. Evolution des teneurs en carbone organique dans l'horizon de surface des sols cultivés en Alsace : Analyse à partir de la Base de Données de Analyses de Terre. Etude et Gestion des Sols 19(3) :179-192. [in French].
  • Walkley, A., Black, C.A., 1934. An examination of Digestion method for determining soil organic matter and proposed modification of the chromic acid titration method. Soil Science 37(1): 29-38.
  • Youl, S., 2005. Dynamique et modélisation de la dynamique du carbone dans un agrosystème de savane de l'Ouest du Burkina Faso. Thèse de doctorat unique, Université Polytechnique de Bobo Dioulasso (UPS) du Burkina Faso. 144p. [in French].
There are 43 citations in total.

Details

Primary Language English
Journal Section Articles
Authors

Awé Djongmo Victor This is me 0000-0002-8493-6695

Noiha Noumi Valery This is me 0000-0003-1036-883X

Alaam Iyawa Francois This is me 0000-0002-3687-4557

Tengomo Donhakia Christiane Vanissa This is me 0000-0001-9634-0357

Mbang Paulidore This is me 0000-0003-0642-769X

Zapfack Louis This is me 0000-0002-0958-0916

Publication Date January 1, 2021
Published in Issue Year 2021 Volume: 10 Issue: 1

Cite

APA Victor, A. D., Valery, N. N., Francois, A. I., Vanissa, T. D. C., et al. (2021). Dynamics of soil organic carbon stock under different types of savannah agrosystems in the Sudano-Sahelian zone of Cameroon. Eurasian Journal of Soil Science, 10(1), 51-60. https://doi.org/10.18393/ejss.809272