Denitrification in a subtropical, semi-arid North American savanna: field measurements and intact soil core incubations

Abstract

Information on denitrification (particularly N2) losses from dry ecosystems is limited despite their large area. Here, we present the first direct denitrification measurements for a northern hemisphere savanna, a Prosopis-dominated grassland/grove matrix in south Texas. We used the gas-flow intact soil core method to quantify N2, N2O and CO2 losses and compared these with field measurements of N2O, NOy, NH3 and CO2. Under field-realistic soil moisture and O2 conditions (average 17.5–20 % O2, minimum 15 %) incubated soils produced no measurable N2 flux (detection limit 52.2 µg N m−2 h−1). Only in a subset of grove soils were fluxes of 70–75 µg N m−2 h−1 recorded after 102 h of incubation at 5–10 % O2 following wetting of very dry soils. Making the assumption that potential N2 production falls just below the detection limit (likely an overestimate given the conditions needed to generate measurable fluxes), N2 flux rates would fall on the low end of that recorded for a tropical Australian savanna (45–110 µg N m−2 h−1) under comparable abiotic conditions. Assuming maximum possible production rates, N2 could comprise <32–76 % of total soil N gas flux following soil wetting in summer. Lack of flux response to soil wetting in winter suggests that cold-season N2 fluxes are negligible. N2O fluxes for core incubations were significantly higher than for field chambers; thus it is likely that incubations may overestimate N2O flux by reducing soil column consumption. Overall, results indicate that soil N2 fluxes are less dominant in this savanna than in other ecosystems investigated.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3

References

  1. Archer S, Boutton T, Hibbard K (2001) Trees in grasslands: biogeochemical consequences of woody plant expansion. In: Schulze E-D, Harrison M, Heimann M et al (eds) Global biogeochemical cycles in the climate system. Academic Press, San Diego, pp 115–138

    Google Scholar 

  2. Austin A, Yahdjian L, Stark J et al (2004) Water pulses and biogeochemical cycles in arid and semiarid ecosystems. Oecologia 141:221–235. doi:10.1007/s00442-004-1519-1

    Article  Google Scholar 

  3. Boutton TW, Liao JD (2010) Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape. J Geophys Res 115:G03019. doi:10.1029/2009JG001184

    Google Scholar 

  4. Burgin AJ, Groffman PM (2012) Soil O2 controls denitrification rates and N2O yield in a riparian wetland. J Geophys Res 117:G01010. doi:10.1029/2011JG001799

    Google Scholar 

  5. Burgin AJ, Groffman PM, Lewis DN (2010) Factors regulating denitrification in a riparian wetland. Soil Sci Soc Am J 74:1826–1833. doi:10.2136/sssaj2009.0463

    Article  Google Scholar 

  6. Butterbach-Bahl K, Willibald G, Papen H (2002) Soil core method for direct simultaneous determination of N2 and N2O emissions from forest soils. Plant Soil 240:105–116. doi:10.1023/A:1015870518723

    Article  Google Scholar 

  7. Butterbach-Bahl K, Kock M, Willibald G et al (2004) Temporal variations of fluxes of NO, NO2, N2O, CO2, and CH4 in a tropical rain forest ecosystem. Glob Biogeochem Cycles. doi:10.1029/2004GB002243

    Google Scholar 

  8. Clough TJ, Sherlock RR, Rolston DE (2005) A review of the movement and fate of N2O in the subsoil. Nutr Cycl Agroecosys 72:3–11. doi:10.1007/s10705-004-7349-z

    Article  Google Scholar 

  9. Dannenmann M, Butterbach-Bahl K, Gasche R et al (2008) Dinitrogen emissions and the N2:N2O emission ratio of a Rendzic Leptosol as influenced by pH and forest thinning. Soil Biol Biogeochem 40:2317–2323. doi:10.1016/j.soilbio.2008.05.009

    Article  Google Scholar 

  10. Dannenmann M, Willibald G, Sippel S, Butterbach-Bahl K (2011) Nitrogen dynamics at undisturbed and burned Mediterranean shrublands of Salento Peninsula, Southern Italy. Plant Soil 343:5–15. doi:10.1007/s11104-010-0541-9

    Article  Google Scholar 

  11. Davidson EA, Vitousek PM, Riley R et al (1991) Soil emissions of nitric oxide in a seasonally dry tropical forest of Mexico. J Geophys Res 96:15439. doi:10.1029/91JD01476

    Article  Google Scholar 

  12. Davidson E, Matson P, Vitousek P et al (1993) Processes regulating soil emissions of NO and N2O in a seasonally dry tropical forest. Ecology 74:130–139. doi:10.2307/1939508

    Article  Google Scholar 

  13. Eickenscheidt T, Heinichen J, Augustin J et al (2014) Nitrogen mineralization and gaseous nitrogen losses from waterlogged and drained organic soils in a black alder (Alnus glutinosa (L.) Gaertn.) forest. Biogeosciences 11:2961–2976. doi:10.5194/bg-11-2961-2014

    Article  Google Scholar 

  14. Firestone MK (1982) Biological Denitrification. In: Stevenson FJ (ed) Nitrogen in agricultural soils. Soil Science Society of America, Madison, pp 289–326

    Google Scholar 

  15. Galbally IE, Kirstine WV, Meyer CPM, Wang YP (2008) Soil-atmosphere trace gas exchange in semiarid and arid zones. J Environ Qual 37:599–607. doi:10.2134/jeq2006.0445

    Article  Google Scholar 

  16. Garcia-Pichel F, Belnap J (1996) Microenvironments and microscale productivity of cyanobacterial desert crusts. J Phycol 32:774–782. doi:10.1111/j.0022-3646.1996.00774.x

    Article  Google Scholar 

  17. Groffman P, Brumme R, Butterbach-Bahl K et al (2000) Evaluating annual nitrous oxide fluxes at the ecosystem scale. Glob Biogeochem Cycles 14:1061–1070. doi:10.1029/1999GB001227

    Article  Google Scholar 

  18. Groffman P, Altabet M, Böhlke J et al (2006) Methods for measuring denitrification: diverse approaches to a difficult problem. Ecol App 16:2091–2122. doi:10.1890/1051-0761

    Article  Google Scholar 

  19. Groffman P, Butterbach-Bahl K, Fulweiler R et al (2009) Challenges to incorporating spatially and temporally explicit phenomena (hotspots and hot moments) in denitrification models. Biogeochemistry 93:49–77. doi:10.1007/s10533-008-9277-5

    Article  Google Scholar 

  20. Hartley A, Barger N, Belnap J, Oskin G (2007) Dryland ecosystems. In: Marschner P, Rengel Z (eds) Nutrient cycling in terrestrial ecosystems: soil biology, vol 10. Springer, Berlin, pp 271–307

    Google Scholar 

  21. Hibbard K, Archer S, Schimel D, Valentine D (2001) Biogeochemical changes accompanying woody plant encroachment in a subtropical savanna. Ecology 82:1999–2011

    Article  Google Scholar 

  22. Hutley L, Setterfield S (2008) Savanna. In: Jorgensen SE, Fath BD (eds) Encyclopedia of Ecology. Elsevier, Oxford, pp 3143–3154

    Google Scholar 

  23. Kulkarni MV, Groffman PM, Yavitt JB (2008) Solving the global nitrogen problem: it’s a gas! Front Ecol Environ 6:199–206. doi:10.1890/060163

    Article  Google Scholar 

  24. Kulkarni MV, Burgin AJ, Groffman PM, Yavitt JB (2013) Direct flux and 15N tracer methods for measuring denitrification in forest soils. Biogeochemistry 117:359–373. doi:10.1007/s10533-013-9876-7

    Article  Google Scholar 

  25. Liu F, Wu X, Bai E et al (2010) Spatial scaling of ecosystem C and N in a subtropical savanna landscape. Glob Change Biol 16:2213–2223. doi:10.1111/j.1365-2486.2009.02099.x

    Article  Google Scholar 

  26. McCalley CK, Strahm BD, Sparks KL et al (2011) The effect of long-term exposure to elevated CO2 on nitrogen gas emissions from Mojave Desert soils. J Geophys Res 116:G03022. doi:10.1029/2011JG001667

    Google Scholar 

  27. Morse JL, Duran J, Beall F, Enanga E, Creed IF, Fernandez IJ, Groffman PM (2015a) Soil denitrification fluxes from three northeastern North American across a range of nitrogen deposition. Oecologia 177:17–27. doi:10.1007/s00442-014-3117-1

    Article  Google Scholar 

  28. Morse JL, Duran J, Groffman PM (2015b) Denitrification and greenhouse gas fluxes in a northern hardwood forest: the importance of snowmelt and implications for ecosystem N budgets. Ecosystems 18:520–532. doi:10.1007/s10021-015-9844-2

    Article  Google Scholar 

  29. Moulin AP, Glenn A, Tenuta M et al (2014) Alternative transformations of nitrous oxide soil flux data to normal distributions. Can J Soil Sci 94:105–108. doi:10.4141/cjss2013-008

    Article  Google Scholar 

  30. Peterjohn W, Schlesinger W (1991) Factors controlling denitrification in a Chihuahuan desert ecosystem. Soil Sci Soc Am J 55:1694–1701. doi:10.2136/sssaj1991.03615995005500060032x

    Article  Google Scholar 

  31. Pinder RW, Bettez ND, Bonan GB et al (2012) Impacts of human alteration of the nitrogen cycle in the US on radiative forcing. Biogeochemistry 114:25–40. doi:10.1007/s10533-012-9787-z

    Article  Google Scholar 

  32. R Core Team (2013) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/

  33. Raciti SM, Burgin AJ, Groffman PM et al (2011) Denitrification in Suburban Lawn Soils. J Environ Qual 40:1932–1940. doi:10.2134/jeq2011.0107

    Article  Google Scholar 

  34. Saggar S, Jha N, Deslippe J et al (2013) Denitrification and N2O:N2 production in temperate grasslands: Processes, measurements, modelling and mitigating negative impacts. Sci Total Environ 465:173–195. doi:10.1016/j.scitotenv.2012.11.050

    Article  Google Scholar 

  35. Schimel DS (2010) Drylands in the Earth System. Science 327:418–419. doi:10.1126/science.1184946

    Article  Google Scholar 

  36. Schlesinger WH (2013) An estimate of the global sink for nitrous oxide in soils. Glob Change Biol 19:2929–2931. doi:10.1111/gcb.12239

    Article  Google Scholar 

  37. Scholefield D, Hawkins J, Jackson SM (1997) Development of a helium atmosphere soil incubation technique for direct measurement of nitrous oxide and dinitrogen fluxes during denitrification. Soil Biol Biochem 29:1345–1352. doi:10.1016/S0038-0717(97)00021-7

    Article  Google Scholar 

  38. Schwinning S, Sala O (2004) Hierarchy of responses to resource pulses in arid and semi-arid ecosystems. Oecologia 141:1–10. doi:10.1007/s00442-004-1520-8

    Article  Google Scholar 

  39. Simek M, Jisova L, Hopkins DW (2002) What is the so-called optimum pH for denitrification in soil? Soil Biol Biochem 34:1227–1234. doi:10.1016/S0038-0717(02)00059-7

    Article  Google Scholar 

  40. Soper FM, Boutton TW, Groffman PM, Sparks JP (2016) Nitrogen trace gas fluxes from a semi-arid subtropical savanna under woody legume encroachment. Glob Biogeochem Cycles 30. doi:10.1002/2015GB005298

  41. Wang R, Willibald G, Feng Q et al (2011) Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique. Environ Sci Tech 45:6066–6072. doi:10.1021/es1036578

    Article  Google Scholar 

  42. Weier K, Doran J, Power J, Walters D (1993) Denitrification and the dinitrogen/nitrous oxide ratio as affected by soil water, available carbon, and nitrate. Soil Sci Soc Am J 57:66–72. doi:10.2136/sssaj1993.03615995005700010013x

    Article  Google Scholar 

  43. Werner C, Reiser K, Dannenmann M et al (2014) N2O, NO, N2, and CO2 emissions from tropical savanna and grassland of Northern Australia: an incubation experiment with intact soil cores. Biogeosci 11:6047–6065. doi:10.5194/bg-11-6047-2014

    Article  Google Scholar 

  44. Wrage N, Velthof GL, van Beusichem ML, Oenema O (2001) Role of nitrifier denitrification in the production of nitrous oxide. Soil Biol Biochem 33:1723–1732. doi:10.1016/S0038-0717(01)00096-7

    Article  Google Scholar 

  45. Yang W, McDowell AC, Brooks PD, Silver WL (2014) New high precision approach for measuring 15N–N2 gas fluxes from terrestrial ecosystems. Soil Biol Biochem 69:234–241. doi:10.1016/j.soilbio.2013.11.009

    Article  Google Scholar 

Download references

Acknowledgments

We thank Shauntle Barley for assistance with sample collection, Kimberlee Sparks, John Pollak, Collin Edwards, David Lewis and Lisa Martel for technical support, and David and Stacy McKown for field logistics. This work was supported a National Science Foundation Doctoral Dissertation Improvement Grant to JPS (Award #1309124), Sigma Xi (Cornell chapter), the Cornell University Betty Miller Francis’47 Fund for Field Research, the Andrew W. Mellon Foundation and the Cornell University Program in Cross-Scale Biogeochemistry and Climate (supported by NSF-IGERT and the Atkinson Center for a Sustainable Future).

Author contributions

FMS, JPS, and PMG formulated the original idea and developed methodology, FMS and JPS conducted field sampling, FMS performed sample analysis and statistical analysis and FMS, PMG and JPS interpreted data and wrote the manuscript.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Fiona M. Soper.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (DOCX 57 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Soper, F.M., Groffman, P.M. & Sparks, J.P. Denitrification in a subtropical, semi-arid North American savanna: field measurements and intact soil core incubations. Biogeochemistry 128, 257–266 (2016). https://doi.org/10.1007/s10533-016-0205-9

Download citation

Keywords

  • Grassland
  • N-FARM
  • di-nitrogen
  • Nitrous oxide
  • Nitric oxide
  • Prosopis