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: Soil mineral nitrogen concentrations and physicochemical properties measured from soil cores in smallholder maize and potato plots in Uasin Gishu County, Kenya [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995352 (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:
Soil mineral nitrogen concentrations (NO₃⁻–N and NH₄⁺–N) and physicochemical properties (pH, soil organic carbon, total nitrogen, C:N ratio, gravimetric soil moisture) measured at multiple depths and 17 sampling time points across the full measurement period in smallholder maize and potato plots in Uasin Gishu County, Kenya. Soil cores were collected from two points along the two inner rows per plot to 60 cm depth in 20 cm increments (0–20, 20–40, 40–60 cm) at 14, 21, 42, 56, 70, 95, 112, 127, 165, 195, 210, 224, 238, 287, 301, 315, and 329 days after planting (DAP). Fresh soil was extracted with 0.5 M K₂SO₄ (10 g soil: 100 mL solution, 1 hour agitation); NO₃⁻–N and NH₄⁺–N concentrations were determined by UV spectrophotometry (BIOBASE BK-D590) at 419 nm and 655 nm, respectively. Gravimetric soil moisture was determined by oven-drying at 105°C for 24 hours. Data span April 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.) on Ferralsol soils. In a randomised complete block design with three replicates, five nitrogen fertilisation rates were applied to maize at 25, 50, 75, 100, 125 kg N ha⁻¹, two rates applied to potato at 50 and 100 kg N ha⁻¹ and unfertilised controls (0 kg N ha-1). 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
Okalebo, J R; Gathua, K W; Woomer, P L (2002): Laboratory Methods of Soil and Plant Analysis: A Working Manual (2nd Edition). Sacred African Publishers, Nairobi, Kenya
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: 2024-04-04T03:00:00 * Date/Time End: 2025-02-27T03:00:00
Minimum DEPTH, soil: 0.1 m * Maximum DEPTH, soil: 0.5 m
Event(s):
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Type of study | Study type | Oluoch, Kevin Churchill | |||
| 2 | DATE/TIME | Date/Time | Oluoch, Kevin Churchill | Geocode – UTC | ||
| 3 | Sample ID | Sample ID | Oluoch, Kevin Churchill | |||
| 4 | Treatment: nitrogen fertilisation | T:N fert | kg/ha | Oluoch, Kevin Churchill | Urea (46% N) applied in 3 split applications | |
| 5 | Treatment: crop type | T:crop | Oluoch, Kevin Churchill | Maize (H 6213) or Potato (Bidii) | ||
| 6 | Species, unique identification | Species UID | Ouma, Turry | Crop type | ||
| 7 | Species, unique identification (Semantic URI) | Species UID (Semantic URI) | Ouma, Turry | Crop type | ||
| 8 | Species, unique identification (URI) | Species UID (URI) | Ouma, Turry | Crop type | ||
| 9 | Block | Block | Ouma, Turry | Randomized complete block design (RCBD) | Replicate | |
| 10 | Depth comment | Depth comm | Oluoch, Kevin Churchill | Soil sampling depth interval | ||
| 11 | DEPTH, soil | Depth soil | m | Oluoch, Kevin Churchill | Geocode – mean | |
| 12 | Depth, soil, minimum | Depth soil min | m | Oluoch, Kevin Churchill | upper | |
| 13 | Depth, soil, maximum | Depth soil max | m | Oluoch, Kevin Churchill | lower | |
| 14 | Time in days | Time d | days | Oluoch, Kevin Churchill | Days after planting | |
| 15 | Growth phase | Growth phase | Oluoch, Kevin Churchill | Crop development stage | ||
| 16 | Nitrogen, as plant-available nitrate | NO3-N plant av | mg/kg | Oluoch, Kevin Churchill | UV/VIS Spectrophotometer, BIOBASE, BK-D590 | Soil nitrate concentration |
| 17 | Nitrogen, as plant-available ammonium | NH4-N plant av | mg/kg | Oluoch, Kevin Churchill | UV/VIS Spectrophotometer, BIOBASE, BK-D590 | Soil ammonium concentration |
| 18 | Nitrate/Ammonium ratio | [NO3]-/[NH4]+ | Oluoch, Kevin Churchill | Calculated | Calculated from measured NO3 and NH4 | |
| 19 | pH, soil | pH soil | Oluoch, Kevin Churchill | pH meter, HANNA Instruments, HI 2211 | measured in soil-water suspension | |
| 20 | Carbon, organic, total | TOC | % | Oluoch, Kevin Churchill | Calculated | soil; Walkley-Black method according to Okalebo et al. (2002) |
| 21 | Nitrogen, total | TN | % | Oluoch, Kevin Churchill | Calculated | soil; Kjeldahl method and colorimetric analysis according to Okalebo et al. (2002) |
| 22 | Carbon, organic, total/Nitrogen, total ratio | TOC/TN | Oluoch, Kevin Churchill | Calculated | Soil carbon-to-nitrogen ratio. Calculated from TOC and TN concentrations | |
| 23 | Soil moisture | Soil moisture | % | Oluoch, Kevin Churchill | see comment | content; soil moisture probe or gravimetric method |
| 24 | Temperature, soil | T soil | °C | Oluoch, Kevin Churchill | Soil moisture and temperature sensor, METER, TEROS 11 | Average soil temperature |
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:
17072 data points
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