Ouma, Turry; Barthel, Matti; Oluoch, Kevin Churchill; Otinga, Abigael; Njoroge, Ruth; Leitner, Sonja; Oduor, Collins; Agredazywczuk, Phillip; Zhu, Yuhao; Tamburini, Federica; Obozinski, Guillaume; Six, Johan; Harris, Eliza: Nitrous oxide isotopologue signatures measured from static chambers in smallholder maize and potato plots in Uasin Gishu County, Kenya [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995349 (dataset in review), In: Ouma, T et al.: A multi-variable high-resolution dataset of N2O fluxes, isotopologue signatures, greenhouse gas fluxes, soil mineral nitrogen, microclimate, and crop yield from smallholder maize and potato systems [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995337 (dataset in review)
Abstract:
N₂O isotopologue signatures – including bulk δ¹⁵N (‰ vs. air N₂), intramolecular site preference (δ¹⁵N^SP = δ¹⁵Nα − δ¹⁵Nβ, ‰), and δ¹⁸O (‰ vs. VSMOW) – measured from headspace gas samples collected monthly from static chambers in smallholder maize and potato plots in Uasin Gishu County, Kenya. This is the first field-scale N₂O isotopologue dataset from a sub-Saharan African agroecosystem. Gas samples were collected by syringe (180 mL per sample) 36 minutes after chamber closure and stored in pre-evacuated crimp-top vials. Isotopologue composition was determined using an Elementar Trace Gas purge-and-trap system coupled to an Elementar IsoPrime100 isotope ratio mass spectrometer (IRMS); five Faraday cups (m/z 30, 31, 44, 45, 46) measured N₂O isotopologues simultaneously. Data span from March 2024 to March 2025 at the University of Eldoret, Uasin Gishu County, Kenya (0°34′45″N, 35°18′22″E; 2,213 m a.s.l.). Four nitrogen fertilisation rates were applied to maize and potato in a randomised complete block design with three replicates: maize at 50 kg N ha⁻¹ , maize at 100 kg N ha⁻¹, potato at 50 kg N ha⁻¹ , and potato at 100 kg N ha⁻¹. Samples with IRMS peak area below 5 mV·s are flagged as low-signal and excluded from pathway partitioning calculations. Data were collected to attribute N₂O emissions to specific microbial production pathways and to quantify in-soil N₂O reduction to N₂ across contrasting crop and fertilisation treatments. This dataset is part of a multi-variable collection archived at PANGAEA.
Supplement to:
Ouma, Turry; Barthel, Matti; Oluoch, Kevin Churchill; Otinga, Abigael; Njoroge, Ruth; Leitner, Sonja; Oduor, Collins; Agredazywczuk, Phillip; Zhu, Yuhao; Tamburini, Federica; Obozinski, Guillaume; Six, Johan; Harris, Eliza (submitted): A multi-variable dataset of N₂O fluxes, isotopologue signatures, soil mineral nitrogen, greenhouse gas emissions, and microclimate from smallholder maize and potato systems in Uasin Gishu County, Kenya (March 2024–March 2025). Earth System Science Data
Related to:
Oluoch, Kevin Churchill; Njoroge, Ruth; Otinga, Abigael; Mutua, Scholastica; Ouma, Turry; Agredazywczuk, Phillip; Barthel, Matti; Six, Johan; Collins, Oduro; Leitner, Sonja; Tufail, Muhammad; Oyugi, Antony; Harris, Eliza (preprint): Fate of Nitrogen in Rainfed Maize (Zea mays) Systems of the Tropical Highlands of Kenya Under Increasing Nitrogen Fertiliser Application Rates. https://doi.org/10.2139/ssrn.5912075
References:
Butterbach-Bahl, Klaus; Gasche, R; Breuer, Lutz; Papen, H (1997): Fluxes of NO and N2O from temperate forest soils: impact of forest type, N deposition and of liming on the NO and N2O emissions. Nutrient Cycling in Agroecosystems, 48(1-2), 79-90, https://doi.org/10.1023/A:1009785521107
IUSS Working Group WRB (2007): World Reference Base for Soil Resources 2006, first update 2007. World Soil Resources Reports No. 103. FAO, Rome
Zhu, Yuhao; Butterbach-Bahl, Klaus; Merbold, Lutz; Oduor, Collins; Gakige, Jesse Kagai; Mwangi, Paul; Leitner, Sonja (2024): Greenhouse gas emissions from sheep excreta deposited onto tropical pastures in Kenya. Agriculture, Ecosystems & Environment, 359, 108724, https://doi.org/10.1016/j.agee.2023.108724
Funding:
Swiss National Science Foundation (SNF), grant/award no. 207348: N2O-SSA: Combining measurements, modelling and machine learning to improve N2O accounting for sustainable agricultural development in sub-Saharan Africa
Coverage:
Latitude: 0.579720 * Longitude: 35.306110
Date/Time Start: 2024-03-05T03:00:00 * Date/Time End: 2024-11-20T03:00:00
Minimum Elevation: 2213.0 m * Maximum Elevation: 2213.0 m
Event(s):
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Type of study | Study type | Ouma, Turry | |||
| 2 | DATE/TIME | Date/Time | Ouma, Turry | Geocode – UTC | ||
| 3 | Treatment: nitrogen fertilisation | T:N fert | kg/ha | Ouma, Turry | Urea (46% N) applied in 3 split applications | |
| 4 | Treatment: crop type | T:crop | Ouma, Turry | Maize (H 6213) or Potato (Bidii) | ||
| 5 | Species, unique identification | Species UID | Ouma, Turry | Crop type | ||
| 6 | Species, unique identification (Semantic URI) | Species UID (Semantic URI) | Ouma, Turry | Crop type | ||
| 7 | Species, unique identification (URI) | Species UID (URI) | Ouma, Turry | Crop type | ||
| 8 | Nitrous oxide, dry air | N2O air | ppmv | Ouma, Turry | Cavity ring down spectrometer, G2308, Picarro Inc. | Headspace, concurrent measurement. Used for two-point mixing model correction |
| 9 | δ15N, nitrous oxide | δ15N N2O | ‰ air | Ouma, Turry | Isotope ratio mass spectrometer (IRMS), Elementar, IsoPrime100 | bulk; m/z 44, 45, 46; vs air N2; soil-emitted value derived from two-point mixing model |
| 10 | δ15N-alpha, nitrous oxide | δ15Na N2O | ‰ air | Ouma, Turry | Isotope ratio mass spectrometer (IRMS), Elementar, IsoPrime100 | m/z 30, 31 NO fragment; vs air N2; central nitrogen atom |
| 11 | δ15N-beta, nitrous oxide | δ15Nb N2O | ‰ air | Ouma, Turry | Isotope ratio mass spectrometer (IRMS), Elementar, IsoPrime100 | mass balance from bulk and alpha; vs air N2; terminal nitrogen atom |
| 12 | Site preference, N2O | SP N2O | ‰ | Ouma, Turry | Calculated | Calculated as delta15N-alpha minus delta15N-beta. Key pathway indicator: nitrification ~+30 permil; bacterial denitrification ~0 permil |
| 13 | δ18O, nitrous oxide | δ18O N2O | ‰ SMOW | Ouma, Turry | Isotope ratio mass spectrometer (IRMS), Elementar, IsoPrime100 | vs VSMOW; analytical precision 1.25 permil |
| 14 | Signal peak area | Sig peak a | mV s | Ouma, Turry | Gas chromatography - isotope ratio mass spectrometry (GC-IRMS), Thermo Fisher Scientific, DELTA V Plus | Indicator of signal reliability; samples with area < 5 flagged as low-signal |
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0) (License comes into effect after moratorium ends)
Status:
Curation Level: Enhanced curation (CurationLevelC)
Size:
2028 data points
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