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Nitrification inhibitors and fertiliser nitrogen application timing strategies to reduce N2O. Site in Devon, 2011

Related Party - Organisation (Author): Rothamsted Research - North Wyke
Related Party - Organisation (Funder): Defra
At a grassland site near Rothamsted Research, North Wyke in south-west England (sandy clay loam topsoil texture), direct nitrous oxide (N2O) and ammonia (NH3) emissions were measured from replicated (x3) plots (12 x 13 m) following spring applications of manufactured nitrogen (N) fertilisers to grassland. A control treatment was included where no N fertiliser was applied. Ammonium nitrate (AN) fertiliser (34.5% N), urea fertiliser (46% N) or an ammonium sulphate nitrate (ASN) fertiliser (26% N) were applied at a rate of 120 kg N ha-1 in two equal split applications (mid- and late April). In separate treatments, two commercially available nitrification inhibitors were tested; dicyandiamide (DCD) was sprayed onto the AN and urea plots immediately after N fertiliser application, and a 3,4-dimethylpyrazole phosphate (DMPP) containing fertiliser (26% N) was also applied at a rate of 120 kg N ha-1, in two split applications. The DCD was applied in a solution (15 kg DCD ha-1) and sprayed onto the plots immediately after N fertiliser application. The N supplied by the DCD was accounted for in the 120 kg N ha-1. As separate treatments, AN and urea fertiliser were also applied in four equal splits 1 week apart from mid-April to early May i.e. 'little and often'. Following N fertiliser application, measurements of direct N2O-N were made over c.12 months, using 5 static chambers (0.8 m2 total surface area) per plot and analysed by gas chromatography. Ammonia-N emissions were measured for 3 weeks after each split N fertiliser application, using a wind tunnel technique (one per plot). Indirect N2O-N emissions were estimated from the measured NH3 losses and from using the Intergovernmental Panel on Climate Change (IPCC) default emission factor; namely 1% of volatilised N is lost as N2O-N. Soil moisture (0-10 cm) and soil mineral nitrogen contents (0-10 cm, 2-split AN and control treatments only) were measured at every N2O sampling event, along with continuous measurements of rainfall, air and soil temperatures (5 cm). Grass yields and N offtakes were also measured following the first and second grass cuts in early June and late July 2011. The Devon, 2011 experiment contains data sets of; annual nitrous oxide emission, annual nitrous oxide emission factor, total ammonia loss, soil moisture, top soil mineral nitrogen (selected treatments), temperature, rainfall and associated crop (grass yield and nitrogen offtakes) and soil measurements.

Subject Keywords: Nitrous oxideAmmoniaManufactured nitrogen fertilizersAmmonium nitrateUrea fertilizersAmmonium sulphate nitrateApplication timingNitrification inhibitorsDCDDMPPGrassland soils
Geographic Keywords: DevonSouth West EnglandEnglandUnited Kingdom
Phenomenon Time -  Start Date/Time: 2011-04-14 00:00:00 End Date/Time:  2012-04-12 00:00:00

Geographic Extent -
    Longitude (West): -4.03
    Longitude (East): -3.76
    Latitude (South): 50.72
    Latitude (North): 50.89

Data Quality Statement:
Rothamsted Research is committed to complying with the standards of the RCUK Policy and Guidelines on Governance of Good Research Conduct, Joint Code of Practice for Research (JCoPR), BBSRC Statement on Safeguarding Good Science Practice, BBSRC data sharing policy and the environmental standard, ISO 14001. Rothamsted Research provides a quality-oriented environment: - Senior management approval of science projects before submission to sponsors. - Scrutiny to ratify the statistical design, management and output for all field, glasshouse and CE experiments. - Institute wide information tools, such as databases of standard operating procedures, risk assessments, COSHH forms, scientific samples, chemical stocks, staff CVs, training and laboratory notebooks. - Laboratory notebook procedures to ensure all operations are recorded, signed and dated, primary data are linked to secondary data, sample location is easily identified and in-house training is recorded. - Electronic data are maintained and backed up on networked servers. Every week a full copy is cycled to a separate physical location. - Environmental targets and objectives are set and environmental performance is monitored in accordance with ISO 14001. - A well-defined training programme for postgraduate students. - Experienced, professional staff provide scientists with support services including experimentation under field, glass and controlled environmental conditions. - High quality academic support services (Computing, Library, Statistics, BioImaging, Analytical Labs, Contracts, Finance and Quality Assurance) - Regular calibration and maintenance of equipment. - Senior management approval of all publications prior to submission and a policy that emphasises submission to peer-reviewed journals. - Facilities are available for Rothamsted to conduct work to support pesticide and semiochemical product approval or authorisation under its ORETO licence number 338, expiry 26 March 2018. Work is conducted to the requirements of this licence if specifically requested by sponsors. Note, Rothamsted Research does not follow GLP and is not accredited as a test facility under the Good Laboratory Practice Regulations, 1999. Project Leaders are responsible for science project work, including that of sub-contractors. Project planning involves risk management of the project. Staff and students on appointment are selected on the basis of how their skills meet the requirements of the project. Training is provided at induction and thereafter identified through annual staff appraisal. Responsibilities of staff involved in the project are formally set out in their written job description and forward job plan. Monitoring and improvement of scientific and environmental standards is achieved through the operation of internal and external procedures: - Monitoring of science output by senior management. - Reviewing progress of projects. - Evaluating reports from internal audits of science projects against the JCoPR, from all Rothamsted activities against the requirements of ISO 14001 and from all external audits. Detailed nitrous oxide emission measurement methodology: Direct N2O emissions were measured with five static flux chambers (40 cm wide x 40 cm long x 25 cm high) per plot, covering a total surface area of 0.8 m2. The chambers were of white (i.e. reflective) PVC and un-vented with a weighted lid and neoprene seal allowing an air-tight seal to form following chamber enclosure. Chambers were pushed into the soil up to a depth of 5 cm and remained in place throughout the experiment, except during fertiliser application and grass cutting when chambers were removed, locations were marked, and chambers were re-instated to the same position as prior to removal. Chambers remained open except for a short time on each sampling day. On that day, ten samples of ambient air were taken to represent time zero (T0) N2O samples. From each chamber, after a 40-minute enclosure period (T40) a headspace sample was taken using a 50-ml syringe. Using a double needle system the sample was flushed though a pre-evacuated 20-22 ml glass vial fitted with a chloro-butyl rubber septum and held at atmospheric pressure. The N2O flux was calculated using an assumed linear increase in N2O concentration from the ambient N2O concentration (T0) to the N2O concentration inside the chamber after 40-minutes enclosure (T40) (Chadwick et al., 2014). Throughout each experiment, the linearity of emissions through time was checked routinely from three chambers located on the highest N rate plots. A minimum of four samples were taken from each chamber at 20 min intervals commencing at closure i.e. T0 and spanning the T40 sampling time. In order to minimise the effect of diurnal variation, gas sampling was carried out between 10:00 am and 14:00 pm and where possible between 10:00 am and 12:00 pm as suggested by IAEA (1992) and referred to in the IPCC good practice guidance (IPCC, 2000). Gas samples were analysed as soon as possible after collection (to minimise potential leakage) using gas chromatographs fitted with an electron-capture detector and an automated sample injection system. Following receipt in the laboratory, three replicates of one standard N2O gas were kept with the samples and were used to verify sample integrity during storage. The gas chromatographs were calibrated on a daily basis using certified N2O standard gas mixtures. Following each fertiliser application, N2O flux measurements were carried out in line with the following sampling schedule until the next fertiliser application or for the final application until the end of the monitoring period; measurements were taken for 5 days immediately following fertiliser application, daily for a further 5 days during the next week, twice weekly for the next two weeks, every other week over the next c. four months, decreasing in frequency to monthly until the end of the 12 month sampling period. Prior to the first fertiliser application N2O measurements were taken to provide baseline information. This sampling schedule resulted in an annual total of c.40 sampling days starting from the day of the first fertiliser application. Measurements were taken over 12 months to follow IPCC good practice guidance and so that the results were directly comparable to the IPCC 2006 methodology default emission factor. Nitrous oxide fluxes from the five replicate chambers per plot were averaged. Cumulative fluxes were calculated using the trapezoidal rule to interpolate fluxes between sampling points. References: Chadwick, D.R., Cardenas, L., Misselbrook, T.H., Smith, K.A., Rees, R.M., Watson, C.J., Mcgeough, K.L., Williams, J.R., Cloy, J.M., Thorman, R.E. and Dhanoa, M.S. (2014). Optimizing chamber methods for measuring nitrous oxide emissions from plot-based agricultural experiments. European Journal of Soil Science 65, 295-307. IAEA (1992). Manual on Measurement of Methane and Nitrous Oxide Emissions from Agriculture. International Atomic Energy Agency (IAEA), Vienna, IAEA-TECDOC-674, ISSN 10111-4289. IPCC (2000). Good Practice Guidance And Uncertainty Management in National Greenhouse Gas Inventories. Penman, J., Kruger, D., Galbally, I., Hiraishi, T., Nyenzi, B., Emmanul, S., Buendia, L., Hoppaus, R., Martinsen, T., Meijer, J., Miwa, K. znd Tanabe, K. (Eds). IGES, Japan.
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Rights Statement

This data is published under the licence Open Government Licence (Version 3)

Attribution: T.H. Misselbrook, L.M. Cardenas, V. Camp and N. Donovan

Citation of this data should be as follows:
T.H. Misselbrook, L.M. Cardenas, V. Camp and N. Donovan (2017): Nitrification inhibitors and fertiliser nitrogen application timing strategies to reduce N2O. Site in Devon, 2011. Version:1. [dataset] Freshwater Biological Association [publisher]. doi:10.17865/ghgno349

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