Dr Sami Ullah PhD, M.I. Soil Sci.

Dr Sami Ullah

School of Geography, Earth and Environmental Sciences
Reader in Biogeochemistry

Contact details

School of Geography, Earth and Environmental Sciences
University of Birmingham
B15 2TT

Dr Sami Ullah’s research is mainly focused on the biogeochemistry of nitrogen and its linkages to carbon and phosphorus cycling under global change in soils under forest, peatland/wetland, grassland, and agricultural crops. The impetus of his research is to advance mechanistic understanding of the response of key microbial functions such as denitrification, nitrogen and carbon mineralization, biological nitrogen fixation, greenhouse gas fluxes and soil enzyme activity to land-use and climate change at catchment scale.


  • PhD in Biogeochemistry, Louisiana State University, USA (2001-05)
  • MSc in Wetland Science and Management, Louisiana State University, USA (1999-2001)


Dr Ullah is involved in teaching at undergraduate and postgraduate level in the broader areas of environmental chemistry, analytical methods and field research, physical geography and environmental management.

Postgraduate supervision

I am always on the look out for good quality national and international postgraduate students. You are encouraged to contact me if interested in working in the broader thematic areas of environmental science, biogeochemistry, restoration ecology and pollution control. Prospective students should also follow the link for available studentships within the Doctoral Training Centers of the school and for general information on applying for postgraduate studies in the School of Geography, Earth and Environmental Sciences at the University of Birmingham.



Humans have significantly altered the global biogeochemical cycles of nitrogen and carbon, mainly though industrialization, land use and climate change. These elements play an incredibly strong role in affecting soil health, food security, greenhouse gas emission and ecosystem resilience. My research tackles these complex challenges by blending large scale novel experimental approaches and manipulations (e.g. elevated CO2, atmospheric nitrogen deposition, agricultural best management practices) to answer fundamental questions about changes in process rates, nitrogen and carbon stocks in soils and greenhouse gas emission into air. The outcomes of my research is fundamental for designing soil, land use and ecosystem management strategies, and predicting the future functioning of soils and ecosystems under global change upon which the survival of human kind depends.

The impetus is to advance mechanistic understanding of the response of key biogeochemical functions in soils (e.g. denitrification, N & C mineralization, biological nitrogen fixation, greenhouse gas fluxes and soil enzyme activity) to land-use and global change at catchment scale.

My research is underpinned by the development and application of novel analytical field techniques including stable isotopes and high-resolution sensor technologies to explore novel relationships between nutrient cycling, plant-microbe interaction and environmental conditions. This knowledge supports the development of new conceptual frameworks and feeds into dynamic ecosystems models for a more realistic assessment of the threshold of biogeochemical functional breakdowns under perturbations; and identification of techniques for sustainable utilization of natural resources, ecosystem restoration, food security and protection of environmental quality. My research cut-across the following themes in biogeochemistry:

  • Greenhouse Gas Fluxes and Global Climate Change: Terrestrial forest and wetland soils in watersheds as well as cultivated soils are significant sinks of atmospheric carbon and play a substantial role in greenhouse gas exchanges with the atmosphere. Local to global scale changes in land use types and management, excessive fertilizer use in agriculture and human-induced changes in the climate have shifted the interactive controls of various biotic and abiotic controls of methane, nitrous oxide and carbon dioxide fluxes with the atmosphere. A detailed understanding of both landscape scale and plot scale controls of C sequestration and greenhouse gas fluxes from soils in sub-tropical, temperate and boreal climates makes part of Dr Ullah’s research for reducing greenhouse gas emissions from natural and semi-natural and agricultural ecosystems. Key biogeochemical processes that responsible for greenhouse gas production and consumption in soils such as denitrification, nitrification, microbial respiration, methanogenesis and methanotrophy are investigated using novel in situ techniques and stable isotopes for fingerprinting the sources and rates of greenhouse gas production. 
  • Land Use, Soil Fertility, Food Security and Water quality: Agricultural intensification, excessive fertilizer use, rising food demands and urbanization are often associated with nutrient/pollutant loss into surface and groundwater. Loss of nutrients such as mineral and dissolved organic N and phosphorus (P) from croplands and urban land uses cascading from soils into surface and groundwater results in the degradation of water quality such as eutrophication and hypoxia. Given the significance of maintaining food productivity for human consumption, Dr Ullah’s research identifies soil and landscape management practices that reduces loss of nutrients from soil into water and improves nutrient use efficiency in crop production systems.
  • Restoration Ecology: A tremendous loss of natural wetlands in watersheds mainly due to cultivation and urbanization has in turn led to a significant loss in wetland ecosystem functions and services. There is particular interest to restore wetlands in watersheds in a way that could render key functions of wetlands and services such as carbon sequestration and attenuation of pollutant run-off from cultivation and urban environments beside provision of habitat to wildlife, flood control and groundwater recharge. Dr Ullah’s research explores and identifies restoration techniques that could help recover multiple functional attributes of wetlands within the context of enhanced environmental quality. 


  1. NERC discovery/standard grants (as a lead PI with a Science Excellence score of 10/10), 2019-2022. FACE Underground: can trees in mature forests gain greater access to soil nutrients under elevated atmospheric CO2? Partners at Exeter and Lancaster Universities. Total value ~ £795,000
  2. UKRI and NSF-USA under the joint “Signals in the Soils” call (as a Birmingham PI), 2020-2022. Large Area Distributed Real Time Soil (DiRTS) Monitoring. Partners at Tufts University, Boston, USA and Keele University, UK. Total value ~£1.5 million
  3. NERC Large Grant (as a CoI), 2019-2024. Quinquennial (half-decadal) carbon and nutrient dynamics in temperate forests: Implications for carbon sequestration in a high carbon dioxide world (QUINTUS). Partners at Exeter and Bangor Universities and NERC-CEH. Total value £3.7 million.
  4. Horizon 2020, Mari Currie Global Fellowship (as a Principal Supervisor). 2019 -2022. MarshFlux: The effect of future global climate and land-use change on greenhouse gas fluxes and microbial processes in salt marshes. A three year fellowship awarded to Dr S. Comer-Warmer in partnership of McGill University, Canada. Total value €276,490  
  5. BBSRC Sustainable Agriculture Research Innovation Club grant (as a UoB PI), 2019-2022.Restoring soil health through re-integration of leys and sheep into arable rotationsPartners at Sheffield, Bangor, and Loughborough Universities and three government agencies (NERC-CEH, Rothamsted Research and National Institute of Agricultural Botany).  Total value £944,587
  6. Newton Institutional Link grant (as a CoI), 2019-2020. Towards smart phone-assisted sensors for monitoring soil nutrients in sustainable farming” in collaboration of the Universidad National de Ingenieria, Peru and Keele University, UK. Total value £100,000.
  7. JABS Foundation UK PhD studentship (as a CoI), 2019-2022. Nutrient and water uptake from fertilizer rich irrigation water by replanted oak forests: efficiencies and loopholes. Total value £80,676.
  8. Leverhulme Trust Doctoral Scholarship (as a contributor), 2018-22. The Forest Edge: a Leverhulme Doctoral Scholarships, led by R. Mackenzie (UoB). Total value £1,050,000.
  9. Institute of Global Innovations-Water Theme, University of Birmingham (as a PI). 2018-2020. Research grant. Tropical forested swamps and mangroves: ecosystem resilience and rural agrarian livelihood under changing climate in Southeast Asia. Total £45,000


  1. Newton Fund Institutional Link grant (as a CoI). 2017-2019. “Towards Precision Agriculture” with partners at Keele University and the Prince of Songkla University, Thailand. Total value £75,000
  2. NERC’S Macronutrient Cycling Program (as a Keele University PI, £398,960), 2012-2015. LTLS: Analysis and simulation of the Long-Term / Large-Scale interactions of C, N and P in UK land, freshwater and atmosphere.  Lead PI at NERC’s CEH and partners at Rothamsted Research, James Hutton Institute, Lancaster, Liverpool, and UCL Universities. Total value, £2.5 million.
  3. Estonian Research Council (as principal supervisor), 2016-2018. Greenhouse gas (N2O and CH4) fluxes from global organic/peat soils under cultivation and natural conditions. International outgoing Fellowship awarded to Dr Jaan Parn. Total value €90,500.
  4. Royal Society, UK Research Grant (as a PI), 2015-2016. Respiratory reduction of nitrous oxide: linkages to biological nitrogen fixation in peatbogs. Total value £6266.
  5. NERC Life Science Mass Spectrometry Facility, British Bryological Society & Keele University (CEH-L086-05-2015) (as principal supervisor), 2015-2019. PhD studentship on biological N fixation in UK and Swedish peatlands. Partners at Swedish University of Agricultural Science, Umea. Total value £71,240
  6. Santandar Research, (as a PI), Grant for networking in the global south, Brazil. Total value £3000.
  7. Nigerian PhD Studentship, (as a co supervisor) 2014-2018. Development of in situ sensing techniques for mineral N in soils and water using ion selective electrodes. Total value £58,000.
  8. Royal Society of Chemistry and Analytical Chemistry Trust Fund (as a PI), 2014-15. Dissimilatory nitrate reduction to ammonium and organic carbon quality in forest, peat and grassland soils. Total value £2960.
  9. EU-European Regional Development Fund Project (as a PI), 2014. Efficient cattle slurry management for nutrient delivery: a consultancy project in support of Acrobat Ltd as an SME. Total value £3500.
  10. Faculty of Natural Science, Keele University competitive analytical infrastructure support (as a lead proposer). 2012-2014. Secured funding for Thermo Flash organic elemental analyser, Lachat Flow Injection Analyser and Agilent custom-made greenhouse gas analyser. Total value £93,000.
  11. British Society of Soil Science. 2014. Portable Soil Science testing kit for summer research experience. Total value £700).
  12. HydroQuebec Inc. Canada (as a PI), 2006-08. Trace gas fluxes and N mineralization in boreal forested wetlands prior to inundation by dams,  at McGill University as PDRA. Total value $13200
  13. Global Environmental and Climate Change Centre, McGill University, Postdoctoral Visiting Research Award.2008. Isotopic application for gross N mineralization rates in soils at the University of Saskatchewan Stable Isotope Research Facility, Canada. Total value $2500.
  14. Rutgers Horticulture Enhancement Grants, Rutgers University, USA (as a PI). Assessment of riparian forests in improving water quality in southern New Jersey, USA. Total value $41000$.


I am always on the look out for good quality national and international postgraduate students. You are encouraged to contact me if interested in working in the broader thematic areas of environmental science, biogeochemistry,  restoration ecology and pollution control. Prospective students should also follow the link for available studentships within the Doctoral Training Centers of the school and for general information on applying for postgraduate studies in the School of Geography, Earth and Environmental Sciences at the University of Birmingham.

Other activities

  • Associate Editor, Soil Use and Management Journal
  • Member, NERCs Peer Review College, RCUK.
  • Chair, Midlands Soil Discussion Group, UK
  • Council Member, British Society of Soil Science
  • Member, Grants Committee, British Society of Soil Science
  • Member, American Geophysical Union
  • Member European Geoscience Union
  • Adjunct Professor, Department of Geography, McGill University (2011-14)
  • Fulbright Scholar, USIS at Louisiana State University, USA (1999-2001)
  • Grant reviewer and panel member for various national and international funding agencies (UK, Austria, EU, and USA).


Recent publications


Saiz, E, Sgouridis, F, Drifjhout, F, Peichl, M, Nilsson, M & Ullah, S 2021, 'Chronic atmospheric reactive nitrogen deposition suppresses biological nitrogen fixation in peatlands', Environmental Science and Technology. https://doi.org/10.1021/acs.est.0c04882

Wang, Y, Zhang, P, Li, M, Guo, Z, Ullah, S, Rui, Y & Lynch, I 2020, 'Alleviation of nitrogen stress in rice (Oryza sativa) by ceria nanoparticles', Environmental Science: Nano, vol. 7, no. 10, pp. 2930-2940. https://doi.org/10.1039/D0EN00757A

Fayose, T, Thomas, E, Radu, T, Dillingham, P, Ullah, S & Radu, A 2020, 'Concurrent measurement of nitrate and ammonium in water and soil samples using ion‐selective electrodes: Tackling sensitivity and precision issues', Analytical Sciences Advances.

Ma, J, Ullah, S, Niu, A, Liao, Z, Qin, Q, Xu, S & Lin, C 2020, 'Heavy metal pollution increases CH4 and decreases CO2 emissions due to soil microbial changes in a mangrove wetland: Microcosm experiment and field examination', Chemosphere. https://doi.org/10.1016/j.chemosphere.2020.128735

Comer-Warner, SA, Gooddy, DC, Ullah, S, Glover, L, Kettridge, N, Wexler, SK, Kaiser, J & Krause, S 2020, 'Seasonal variability of sediment controls of nitrogen cycling in an agricultural stream', Biogeochemistry, vol. 148, no. 1, pp. 31-48. https://doi.org/10.1007/s10533-020-00644-z

Comer-Warner, SA, Romeijn, P, Gooddy, DC, Ullah, S, Kettridge, N, Marchant, B, Hannah, DM & Krause, S 2019, 'Addendum: Thermal sensitivity of CO2 and CH4 emissions varies with streambed sediment properties', Nature Communications, vol. 10, no. 1, 3093 . https://doi.org/10.1038/s41467-019-11185-x

Saiz, E, Sgouridis, F, Drifjhout, F & Ullah, S 2019, 'Biological nitrogen fixation in peatlands: comparison between acetylene reduction assay and 15N2 assimilation methods', Soil Biology and Biochemistry, vol. 131, pp. 157-165. https://doi.org/10.1016/j.soilbio.2019.01.011

Lu, X, Vogt, RD, Han, S, Li, H, Mo, X, Ullah, S, Zhang, Y, Chen, C, Han, X, Li, H & Seip, HM 2019, 'China’s ineffective plastic solution to haze', Science. https://doi.org/10.1126/science.aax5674

Comer-Warner, SA, Romeijn, P, Gooddy, DC, Ullah, S, Kettridge, N, Marchant, B, Hannah, DM & Krause, S 2019, 'Reply to ‘Pseudoreplication and greenhouse-gas emissions from rivers'', Nature Communications. https://doi.org/10.1038/s41467-019-13304-0

Weatherill, J, Krause, S, Ullah, S, Cassidy, N, Levy, A, Drifjhout, F & Rivett, MO 2019, 'Revealing chlorinated ethene transformation hotspots in a nitrate impacted hyporheic zone', Water Research, vol. 161, pp. 222-231. https://doi.org/10.1016/j.watres.2019.05.083

Comer-Warner, SA, Gooddy, DC, Ullah, S, Glover, L, Percival, A, Kettridge, N & Krause, S 2019, 'Seasonal variability of sediment controls of carbon cycling in an agricultural stream', Science of the Total Environment, vol. 688, pp. 732-741. https://doi.org/10.1016/j.scitotenv.2019.06.317

Romeijn, P, Comer-warner, SA, Ullah, S, Hannah, DM & Krause, S 2019, 'Streambed organic matter controls on carbon dioxide and methane emissions from streams', Environmental Science and Technology, vol. 53, no. 5, pp. 2364-2374. https://doi.org/10.1021/acs.est.8b04243


Pärn, J, Verhoeven, JTA, Butterbach-Bahl, K, Dise, NB, Ullah, S, Aasa, A, Egorov, S, Espenberg, M, Järveoja, J, Jauhiainen, J, Kasak, K, Klemedtsson, L, Kull, A, Laggoun-Défarge, F, Lapshina, ED, Lohila, A, Lõhmus, K, Maddison, M, Mitsch, WJ, Müller, C, Niinemets, Ü, Osborne, B, Pae, T, Salm, JO, Sgouridis, F, Sohar, K, Soosaar, K, Storey, K, Teemusk, A, Tenywa, MM, Tournebize, J, Truu, J, Veber, G, Villa, JA, Zaw, SS & Mander, Ü 2018, 'Erratum: author correction: nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots (Nature communications (2018) 9 1 (1135))', Nature Communications, vol. 9, no. 1, 1748 . https://doi.org/10.1038/s41467-018-04197-6

Review article

Comer-Warner, S, Knapp, JLA, Blaen, P, Klaar, M, Shelley, F, Zarnetske, J, Lee-Cullin, J, Folegot, S, Kurz, M, Lewandowski, J, Harvey, J, Ward, A, Mendoza-Lera, C, Ullah, S, Datry, T, Kettridge, N, Gooddy, D, Drummond, J, Martí, E, Milner, A, Hannah, D & Krause, S 2020, 'The method controls the story - Sampling method impacts on the detection of pore-water nitrogen concentrations in streambeds', Science of the Total Environment, vol. 709, 136075. https://doi.org/10.1016/j.scitotenv.2019.136075

Weatherill, JJ, Atashgahi, S, Schneidewind, U, Krause, S, Ullah, S, Cassidy, N & Rivett, MO 2018, 'Natural attenuation of chlorinated ethenes in hyporheic zones: A review of key biogeochemical processes and in-situ transformation potential', Water Research, vol. 128, pp. 362-382. https://doi.org/10.1016/j.watres.2017.10.059

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