How Does Heat-Stress Intensity Affect the Stability of Microbial Activity and Diversity of Soil Microbial Communities in Outfields and Homefields’ Cultivation Practices in the Senegalese Groundnut Basin?
Agroecosystems in the Senegalese groundnut basin experience long periods of high temperatures and drought, which disrupt the stability of soil microbial communities. This study evaluated how that stability is affected by homefields and outfields’ agricultural practices and the duration of heat stress. Specifically, we collected soils from organically farmed fields that receive continual high inputs of manure (homefields), and from fields that are rarely manured (outfields). Soil samples were submitted to artificial heat stress at 60°C for 3, 14, and 28 days, followed by 28 days of recovery at 28°C. We examined the functional stability of microbial communities by quantifying C mineralization, and characterized the stability of the communities’ taxonomic compositions via high-throughput DNA sequencing. We found that the microbial communities have a low resistance to heat stress in soils from both types of fields. However, the manuring practice does affect how the functional stability of microbial communities responds to different durations of heat stress. Although functional stability was not recovered fully in either soil, microbial community resilience seemed to be greater in homefield soils. Differences in manuring practices also affected the structural taxonomic stability of microbial communities: relative abundances of Bacilli, Chloroflexia, Actinobacteria and Sordariomycetes increased in the homefield stressed-soils, but decreased significantly in outfield soils. In contrast, relative abundances of α-Proteobacteria, γ-Proteobacteria and Eurotiomycetes increased significantly in outfield stressed-soils, while decreasing significantly in the homefield soils. Relative abundances of Bacilli changed little in outfield soils, indicating that this taxon is resistant to heat stress. In summary, the microbial communities’ capacities to resist heat stress and recover from it depend upon the organic richness of the soil (i.e., manuring practice) and the adaptation of soil microbes to environmental conditions.
References
[1]
Chotte, J.L., Diouf, M.N., Assigbetsé, K., Lesueur, D., Rabary, B. and Sall, S.N. (2013) Unexpected Similar Stability of Soil Microbial CO2 Respiration in 20-Year Manured and in Unmanured Tropical Soils. Environmental Chemistry Letters, 11, 135-142. https://doi.org/10.1007/s10311-012-0388-9
[2]
Quéré, C.L., Raupach, M.R., Canadell, J.G., Marland, G., Bopp, L., Ciais, P., Conway, T.J., Doney, S.C., Feely, R.A., Foster, P., Friedlingstein, P., Gurney, K., Houghton, R.A., House, J.I., Huntingford, C., Levy, P.E., Lomas, M.R., Majkut, J., Metzl, N., Ometto, J.P., Peters, G.P., Prentice, I.C., Randerson, J.T., Running, S.W., Sarmiento, J.L., Schuster, U., Sitch, S., Takahashi, T., Viovy, N., Van Der Werf, G.R. and Woodward, F.I. (2009) Trends in the Sources and Sinks of Carbon Dioxide. Nature Geoscience, 2, 831-836. https://doi.org/10.1038/ngeo689
[3]
Li, J.T., Wang, J.J., Zeng, D.H., Zhao, S.Y., Huang, W.L., Sun, X.K. and Hu, Y.L. (2018) The Influence of Drought Intensity on Soil Respiration during and after Multiple Drying-Rewetting Cycles. Soil Biology and Biochemistry, 127, 82-89.
https://doi.org/10.1016/j.soilbio.2018.09.018
[4]
Griffiths, B.S. and Philippot, L. (2013) Insights into the Resistance and Resilience of the Soil Microbial Community. Federation of European Microbiological Societies, 37, 112-129. https://doi.org/10.1111/j.1574-6976.2012.00343.x
[5]
Orwin, K.H. and Wardle, D.A. (2004) New Indices for Quantifying the Resistance and Resilience of Soil Biota to Exogenous Disturbances. Soil Biology and Biochemistry, 36, 1907-1912. https://doi.org/10.1016/j.soilbio.2004.04.036
[6]
Guillot, E., Hinsinger, P., Dufour, L., Roy, J. and Bertrand, I. (2019) With or without Trees: Resistance and Resilience of Soil Microbial Communities to Drought and Heat Stress in a Mediterranean Agroforestry System. Soil Biology and Biochemistry, 129, 122-135. https://doi.org/10.1016/j.soilbio.2018.11.011
[7]
Vries, F.T.D. and Shade, A. (2013) Controls on Soil Microbial Community Stability under Climate Change. Frontiers in Microbiology, 4, 265.
https://doi.org/10.3389/fmicb.2013.00265
[8]
Ng, E.L., Patti, A.F., Rose, M.T., Schefe, C.R., Smernik, R.J. and Cavagnaro, T.R. (2015) Do Organic Inputs Alter Resistance and Resilience of Soil Microbial Community to Drying? Soil Biology and Biochemistry, 81, 58-66.
https://doi.org/10.1016/j.soilbio.2014.10.028
[9]
Dione, M., Diop, O., Dièye, P.N., Ba, D.N. and Ndao, B. (2008) Caractérisation et typologie des exploitations agricoles familiales du Sénégal. In ISRA/UNIVAL 8, 1-31.
[10]
Sall, M., Samb, A.A., Tall, S.M. and Tandian, A. (2011) Changements climatiques, stratégies d’adaptation et mobilités. Evidence à partir de quatres sites au Sénégal. International Institute for Environment and Development (IIED), London, 49 p.
[11]
Acosta-Martinez, V., Moore-Kucera, J., Cotton, J., Gardner, T. and Wester, D. (2014) Soil Enzyme Activities during the 2011 Texas Record Drought/Heat Wave and Implications to Biogeochemical Cycling and Organic Matter Dynamics. Applied Soil Ecology, 75, 43-51. https://doi.org/10.1016/j.apsoil.2013.10.008
[12]
Acosta-Martínez, V., Cotton, J., Gardner, T., Moore-Kucera, J., Zak, J., Wester, D. and Cox, S. (2014) Predominant Bacterial and Fungal Assemblages in Agricultural Soils during A Record Drought/Heat Wave and Linkages to Enzyme Activities of Biogeochemical Cycling. Applied Soil Ecology, 84, 69-82.
https://doi.org/10.1016/j.apsoil.2014.06.005
[13]
Ben Sassi, M. (2012) Impacts d’apports de composts de déchets urbains sur la résistance et la résilience de la microflore du sol à des évènements de type canicule/sécheresse. In Sciences agricoles. Université d’Avignon, Avignon.
[14]
Bérard, A., Bouchet, T., Sévenier, G., Pablo, A.L. and Gros, R. (2011) Resilience of Soil Microbial Communities Impacted by Severe Drought and High Temperature in the Context of Mediterranean Heat Waves. European Journal of Soil Biology, 47, 333-342. https://doi.org/10.1016/j.ejsobi.2011.08.004
[15]
Bandick, A.K. and Dick, R.P. (1999) Field Management Effects on Soil Enzyme Activities. Soil Biology and Biochemistry, 31, 1471-1479.
https://doi.org/10.1016/S0038-0717(99)00051-6
[16]
Bastida, F., Torres, I. F., Hernández, T. and García, C. (2017) The Impacts of Organic Amendments: Do They Confer Stability against Drought on the Soil Microbial Community? Soil Biology and Biochemistry, 113, 173-183.
https://doi.org/10.1016/j.soilbio.2017.06.012
[17]
Hueso, S., Hernández, T. and García, C. (2011) Resistance and Resilience of the Soil Microbial Biomass to Severe Drought in Semiarid Soils: The Importance of Organic Amendments. Applied Soil Ecology, 50, 27-36.
https://doi.org/10.1016/j.apsoil.2011.07.014
[18]
Laval, K., Akpa-vinceslas, M., Barray, S., Dur, J.C., Gangneux, C., Lebrun, J., Legras, M., Lepelletier, P., Plassart, P., Taibi, S. and Trinsoutrot-Gattin, I. (2009) Nouvelles avancées vers la compréhension des données biologiques. étude et Gestion Des Sols, 16, 275-285.
[19]
Kaisermann, A., Roguet, A., Nunan, N., Maron, P.-A., Ostle, N. and Lata, J.C. (2013) Agricultural Management Affects the Response of Soil Bacterial Community Structure and Respiration to Water-Stress. Soil Biology and Biochemistry, 66, 69-77.
https://doi.org/10.1016/j.soilbio.2013.07.001
[20]
Kuan, H.L., Hallett, P.D., Griffiths, B.S., Gregory, A.S., Watts, C.W. and Whitmore, A.P. (2007) The Biological and Physical Stability and Resilience of a Selection of Scottish Soils to Stresses. European Journal of Soil Science, 58, 811-821.
https://doi.org/10.1111/j.1365-2389.2006.00871.x
[21]
Wada, S. and Toyota, K. (2007) Repeated Applications of Farmyard Manure Enhance Resistance and Resilience of Soil Biological Functions against Soil Disinfection. Biology and Fertility of Soils, 43, 349-356.
https://doi.org/10.1007/s00374-006-0116-3
[22]
Fotio, D., Simon, S., Njomgang, R., Nguefack, J., Nguéguim, M., Feujio, N.J.S., Téguefouet, P. and Mfopou, M.Y.C. (2009) Impacts de la gestion du sol sur la biomasse microbienne et le statut organique du sol de la zone ouest du Cameroun. Cirad-Agritrop, 1-13.
[23]
Tounkara, A., Clermont-dauphin, C., A, F., Ndiaye, S., Masse, D. and Cournac, L. (2020) Agriculture, Ecosystems and Environment Inorganic Fertilizer Use Efficiency of Millet Crop Increased with Organic Fertilizer Application in Rainfed Agriculture on Smallholdings in Central Senegal. Agriculture, Ecosystems and Environment, 294, Article ID: 106878. https://doi.org/10.1016/j.agee.2020.106878
[24]
Malou, O.P., Sebag, D., Moulin, P., Chevallier, T., Badiane-Ndour, N.Y., Thiam, A. and Chapuis-Lardy, L. (2020) The Rock-Eval® Signature of Soil Organic Carbon in Arenosols of the Senegalese Groundnut Basin. How Do Agricultural Practices Matter? Agriculture, Ecosystems and Environment, 301, Article ID: 107030.
https://doi.org/10.1016/j.agee.2020.107030
[25]
Lericollais, A. (1988) La mort des arbres à Sob, en pays Sereer (Sénégal). Editions de l’ORSTOM, Paris, 187-197.
[26]
Salack, S., Muller, B., Gaye, A.T., Hourdin, F. and Cisse, N. (2012) Analyses multi-échelles des pauses pluviométriques au Niger et au Sénégal. Secheresse, 23, 3-13.
[27]
ANSD (2015) Situation Economique et Sociale Regionale 2013. In Service Régional de la Statistique et de la Démographie de Kaolack.
[28]
Yin, R., Eisenhauer, N., Auge, H., Purahong, W., Schmidt, A. and Schadler, M. (2019) Additive Effects of Experimental Climate Change and Land Use on Faunal Contribution to Litter Decomposition. Soil Biology and Biochemistry, 131, 141-148.
https://doi.org/10.1016/j.soilbio.2019.01.009
[29]
Pareek, N. (2017) Climate Change Impact on Soils: Adaptation and Mitigation. MOJ Ecology & Environmental Sciences, 2, 136-139.
https://doi.org/10.15406/mojes.2017.02.00026
[30]
Haddaway, N.R., Hedlund, K., Jackson, L.E., Katterer, T., Lugato, E., Thomsen, I.K., Jorgensen, H.B. and Soderstrom, B. (2015) What Are the Effects of Agricultural Management on Soil Organic Carbon in Boreo-Temperate Systems? Environmental Evidence, 4, Article No. 23. https://doi.org/10.1186/s13750-015-0049-0
[31]
Bérard, A., Sassi, M.B., Renault, P. and Gros, R. (2012) Severe Drought-Induced Community Tolerance to Heat Wave. An Experimental Study on Soil Microbial Processes. Journal of Soils and Sediments, 12, 513-518.
https://doi.org/10.1007/s11368-012-0469-1
Steinweg, J.M., Plante, A.F., Conant, R.T., Paul, E.A. and Tanaka, D.L. (2008) Patterns of Substrate Utilization during Long-Term Incubations at Different Temperatures. Soil Biology and Biochemistry, 40, 2722-2728.
https://doi.org/10.1016/j.soilbio.2008.07.002
[34]
Bárcenas-Moreno, G. and Baath, E. (2009) Bacterial and Fungal Growth in Soil Heated at Different Temperatures to Simulate a Range of Fire Intensities. Soil Biology and Biochemistry, 41, 2517-2526. https://doi.org/10.1016/j.soilbio.2009.09.010
[35]
IUSS Working Group WRB (2015) World Reference Base for Soil Resources 2014, Update 2015. International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. World Soil Resources Reports No. 106, FAO, Rome.
[36]
Walkley, A. and Black, I.A. (1934) An Examination of the Degtjareff Method for Determining Soil Organic Matter, and a Proposed Modification of the Chromic Acid Titration Method. Soil Science, 63, 251-263.
https://doi.org/10.1097/00010694-194704000-00001
[37]
Riah-Anglet, W., Trinsoutrot-Gattin, I., Martin-Laurent, F., Laroche-Ajzenberg, E., Norini, M.P., Latour, X., Laval, K. (2015) Soil Microbial Community Structure and Function Relationships: A Heat Stress Experiment. Applied Soil Ecology, 86, 121-130.
https://doi.org/10.1016/j.apsoil.2014.10.001
[38]
Bécaert, V., Samson, R. and Deschênes, L. (2006) Effect of 2,4-D Contamination on Soil Functional Stability Evaluated Using the Relative Soil Stability Index (RSSI). Chemosphere, 64, 1713-1721. https://doi.org/10.1016/j.chemosphere.2006.01.008
[39]
Dussault, M., Bécaert, V., Francois, M., Sauvé, S. and Deschênes, L. (2008) Effect of Copper On Soil Functional Stability Measured by Relative Soil Stability Index (RSSI) Based on Two Enzyme Activities. Chemosphere, 72, 755-762.
https://doi.org/10.1016/j.chemosphere.2008.03.019
[40]
Fierer, N., Schimel, J.P. and Holden, P.A. (2003) Influence of Drying-Rewetting Frequency on Soil Bacterial Community Structure. Microbial Ecology, 45, 63-71.
https://doi.org/10.1007/s00248-002-1007-2
[41]
Jurburg, S.D., Nunes, I., Brejnrod, A., Jacquiod, S., Priemé, A., Sorensen, S.J., Van Elsas, J.D. and Salles, J.F. (2017) Legacy Effects on the Recovery of Soil Bacterial Communities from Extreme Temperature Perturbation. Frontiers Microbiology, 8, Article No. 13. https://doi.org/10.3389/fmicb.2017.01832
[42]
Kumar, S., Patra, A.K., Singh, D., Purakayastha, T.J., Rosin, K.G. and Kumar, M. (2013) Balanced Fertilization along with Farmyard Manures Enhances Abundance of Microbial Groups and Their Resistance and Resilience against Heat Stress in a Semi-Arid Inceptisol. Communications in Soil Science and Plant Analysis, 44, 2299-2313. https://doi.org/10.1080/00103624.2013.803562
[43]
Nielsen, M.N. and Winding, A. (2002) Microorganisms as Indicators of Soil Health. Technical Report No. 388, National Environmental Research Institute, Roskilde.
[44]
Tournier, E., Amenc, L., Pablo, A.L., Legname, E., Blanchart, E., Plassard, C., Robin, A. and Bernard, L. (2015) Modification of a Commercial DNA Extraction Kit for Safe and Rapid Recovery of DNA and RNA Simultaneously from Soil, without the Use of Harmful Solvents. MethodsX, 2, 182-191.
https://doi.org/10.1016/j.mex.2015.03.007
[45]
Agren, G.I. and Wetterstedt, J.A.M. (2007) What Determines the Temperature Response of Soil Organic Matter Decomposition? Soil Biology and Biochemistry, 39, 1794-1798. https://doi.org/10.1016/j.soilbio.2007.02.007
[46]
Franco-Andreu, L., Gómez, I., Parrado, J., García, C., Hernández, T. and Tejada, M. (2017) Soil Biology Changes as a Consequence of Organic Amendments Subjected to a Severe Drought. Land Degradation and Development, 28, 897-905.
https://doi.org/10.1002/ldr.2663
[47]
Rustad, L.E., Campbell, J.L., Marion, G.M., Norby, R.J., Mitchell, M.J., Hartley, A.E., Cornelissen, J.H.C. and Gurevitch, J. (2001) A Meta-Analysis of the Response of Soil Respiration, Net Nitrogen Mineralization, and Aboveground Plant Growth to Experimental Ecosystem Warming. Oecologia, 126, 543-562.
https://doi.org/10.1007/s004420000544
[48]
Davet, P. (1995) Vie microbienne du sol et production végétale. INRA.
https://doi.org/10.1016/S0294-3506(99)80224-5
[49]
Pailler, A. (2013) Les relations sol/plantes en forêts méditerranéennes: Approche bioclimatique des déterminants de la structuration fonctionnelle des communautés microbiennes des sols et de leurs réponses à un double stress hydrique et thermique en région provencale calca. Université d’Aix Marseille.
[50]
Griffiths, B.S., Bonkowski, M., Roy, J. and Ritz, K. (2001) Functional Stability, Substrate Utilisation and Biological Indicators of Soils Following Environmental Impacts. Applied Soil Ecology, 16, 49-61.
https://doi.org/10.1016/S0929-1393(00)00081-0
[51]
Fierer, N. and Schimel, J.P. (2002) Effects of Drying-Rewetting Frequency on Soil Carbon and Nitrogen Transformations. Soil Biology and Biochemistry, 34, 777-787.
https://doi.org/10.1016/S0038-0717(02)00007-X
[52]
Sun, D., Li, K., Bi, Q., Zhu, J., Zhang, Q., Jin, C., Lu, L. and Lin, X. (2017) Effects of Organic Amendment on Soil Aggregation and Microbial Community Composition during Drying-Rewetting Alternation. Science of the Total Environment, 574, 735-743. https://doi.org/10.1016/j.scitotenv.2016.09.112
[53]
Aislabie, J. and Deslippe, J.R. (2013) Soil Microbes and Their Contribution to Soil Services. In: Dymond, J.R., Ed., Ecosystem Services in New Zealand: Conditions and Trends, Manaaki Whenua Press, Lincoln, 143-161.
https://www.landcareresearch.co.nz/assets/Publications/Ecosystem-services-in-New-Zealand/1_12_Aislabie.pdf
[54]
Fierer, N., Breitbart, M., Nulton, J., Salamon, P., Lozupone, C., Jones, R., Robeson, M., Edwards, R.A., Felts, B., Rayhawk, S., Knight, R., Rohwer, F. and Jackson, R.B. (2007) Metagenomic and Small-Subunit rRNA Analyses Reveal the Genetic Diversity of Bacteria, Archaea, Fungi, and Viruses in Soil. American Society for Microbiology, 73, 7059-7066. https://doi.org/10.1128/AEM.00358-07
[55]
Balajee, S.A., Gribskov, J.L., Hanley, E., Nickle, D. and Marr, K.A. (2005) Aspergillus lentulus sp. nov., a New Sibling Species of A. fumigatus. Eukaryotic Cell, 4, 625-632. https://doi.org/10.1128/EC.4.3.625-632.2005
[56]
Bossler, A.D., Richter, S.S., Chavez, A.J., Vogelgesang, S.A., Sutton, D.A., Grooters, A.M., Rinaldi, M.G., De Hoog, G.S. and Pfaller, M.A. (2003) Exophiala oligosperma Causing Olecranon Bursitis. Journal of Clinical Microbiology, 41, 4779-4782.
https://doi.org/10.1128/JCM.41.10.4779-4782.2003
[57]
Fierer, N. (2017) Embracing the Unknown: Disentangling the Complexities of the Soil Microbiome. Nature Reviews Microbiology, 15, 579-590.
https://doi.org/10.1038/nrmicro.2017.87
[58]
Ali, S., Ganai, B.A., Kamili, A.N., Bhat, A.A., Mir, Z.A., Bhat, J.A., Tyagi, A., Islam, S.T., Mushtaq, M., Yadav, P., Rawat, S. and Grover, A. (2018) Pathogenesis-Related Proteins and Peptides as Promising Tools for Engineering Plants with Multiple Stress Tolerance. Microbiological Research, 212-213, 29-37.
https://doi.org/10.1016/j.micres.2018.04.008
[59]
Razanamalala, K., Razafimbelo, T., Maron, P.A., Ranjard, L., Chemidlin, N., Lelièvre, M., Dequiedt, S., Ramaroson, V.H., Marsden, C., Becquer, T., Trap, J., Blanchart, E. and Bernard, L. (2018) Soil Microbial Diversity Drives the Priming Effect along Climate Gradients: A Case Study in Madagascar. International Society for Microbial Ecology, 12, 451-462. https://doi.org/10.1038/ismej.2017.178
[60]
Goldfarb, K.C., Karaoz, U., Hanson, C.A., Santee, C.A., Bradford, M.A., Treseder, K.K., Wallenstein, M.D. and Brodie, E.L. (2011) Differential Growth Responses of Soil Bacterial Taxa to Carbon Substrates of Varying Chemical Recalcitrance. Frontiers in Microbiology, 2, 94. https://doi.org/10.3389/fmicb.2011.00094
[61]
Demharter, W., Hensel, R., Smida, J. and Stackebrandt, E. (1989) Sphaerobacter thermophilus gen. nov., sp. nov. A Deeply Rooting Member of the Actinomycetes Subdivision Isolated from Thermophilically Treated Sewage Sludge. Systematic and Applied Microbiology, 11, 261-266. https://doi.org/10.1016/S0723-2020(89)80023-2
[62]
Preece, C., Verbruggen, E., Liu, L., Weedon, J.T. and Penuelas, J. (2019) Effects of Past and Current Drought on the Composition and Diversity of Soil Microbial Communities. Soil Biology and Biochemistry, 131, 28-39.
https://doi.org/10.1016/j.soilbio.2018.12.022
[63]
Shin, N., Whon, T.W. and Bae, J. (2015) Proteobacteria: Microbial Signature of Dysbiosis in Gut Microbiota. Trends in Biotechnology, 33, 496-503.
https://doi.org/10.1016/j.tibtech.2015.06.011
[64]
Schimel, J., Balser, T.C. and Wallenstein, M. (2007) Microbial Stress-Response Physiology and Its Implications for Ecosystem Function. Ecological Society of America, 88, 1386-1394. https://doi.org/10.1890/06-0219
[65]
Billi, D. and Potts, M. (2002) Life and Death of Dried Prokaryotes. Research in Microbiology, 153, 7-12. https://doi.org/10.1016/S0923-2508(01)01279-7
[66]
Lebouvier, M., Chapuis, J.L., Gloaguen, J.C. and Frenot, Y. (2002) Résilience des communautés insulaires subantarctiques: Facteurs influencant la vitesse de restauration écologique après éradication de mammifères introduits. Revue d’Ecologie (La Terre et La Vie), 57, 189-198. https://doi.org/10.3406/revec.2002.6219
[67]
Allison, S.D. and Martiny, J.B.H. (2008) Resistance, Resilience, and Redundancy in Microbial Communities. PNAS, 105, 11512-11519.
https://doi.org/10.1073/pnas.0801925105
[68]
Scheldeman, P., Herman, L., Foster, S. and Heyndrickx, M. (2006) Bacillus Sporothermodurans and Other Highly Heat-Resistant Spore Formers in Milk. Journal of Applied Microbiology, 101, 542-555.
https://doi.org/10.1111/j.1365-2672.2006.02964.x
[69]
Kampfer, P., Rosselló-Mora, R., Falsen, E., Busse, H.J. and Tindall, B.J. (2006) Cohnella thermotolerans gen. nov., sp. nov. and Classification of “Paenibacillus hongkongensis” as Cohnella hongkongensis sp. nov. International Journal of Systematic and Evolutionary Microbiology, 56, 781-786. https://doi.org/10.1099/ijs.0.63985-0
[70]
Berthou, S., Rowell, D.P., Kendon, E.J., Rachel, R., Julia, S. and Catherine, C. (2018) Improved Climatological Precipitation Characteristics over West Africa at Convection-Permitting Scale. Climate Dynamics Manuscript No. 1-22.
[71]
Stratton, R.A., Senior, C.A., Vosper, S.B., Folwell, S.S., Boutle, I.A., Earnshaw, P.D., Kendon, E., Lock, A.P., Malcolm, A., Manners, J., Morcrette, C.J., Short, C., Stirling, A.J., Taylor, C.M., Tucker, S., Webster, S. and Wilkinson, J.M. (2018) A Pan-African Convection-Permitting Regional Climate Simulation with the Met Office Unified Model: CP4-Africa. Journal of Climate, 31, 3485-3508.
https://doi.org/10.1175/JCLI-D-17-0503.1
