The Effect of N Fertiliser forms on N2O emissions from UK arable and grassland. Experimental site in Devon, 2004

N - Datasets

Misselbrook, T. H. and Yamulki, S. 2017. The Effect of N Fertiliser forms on N2O emissions from UK arable and grassland. Experimental site in Devon, 2004. Freshwater Biological Assoc. https://doi.org/10.17865/ghgno706

AuthorsMisselbrook, T. H. and Yamulki, S.
Abstract

Nitrous oxide emissions (2 closed static chambers/plot) were monitored for about 12 months, following the spring application, by hand, of various nitrogen fertilisers (ammonium nitrate, urea, urea+urease inhibitor nBTPT [trade name Agrotain®] and urea ammonium sulphate) and from an untreated control. Four fertiliser applications were made in order to achieve the target, commercial rate of 300 kg N ha-1. There were 3 replicate plots (2 x 6 m) of each treatment arranged in a randomised block design. The plots were established on grassland, on a sandy silt loam soil (over clay) at North Wyke in south west England, UK. The Devon, 2004 experiment contains data sets of; annual nitrous oxide emissions, annual nitrous oxide emission factors, soil moisture, top soil mineral nitrogen, temperature, rainfall and associated crop & soil measurements.

Year of Publication2017
PublisherFreshwater Biological Assoc
Digital Object Identifier (DOI)https://doi.org/10.17865/ghgno706
Keywordsnitrous oxide
ammonium nitrate
urea
urease inhibitors
grassland soils
Publication dates
Online07 Apr 2017
FunderDepartment of Environment, Food and Rural Affairs
Data files
File Access Level
Open
Data collection period02 Mar 2004 to end of 09 Feb 2005
Geographic location
Devon, South West England, UK
Geographic region bounding box
(50.68, -4.04) to (50.85, -3.75)
Geographic coverageDevon, South West England, UK
Data collection method

Direct N2O emissions were measured with two static flux chambers (40 cm wide x 40 cm long x 25 cm high) per plot, covering a total surface area of 0.32 m2. The chambers were of white (i.e. reflective) PVC and un-vented with a water-filled channel running around the upper rim of the chamber allowing an air-tight seal to form following chamber enclosure with a lid (Smith et al., 2012). 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, eight samples of ambient air were taken to represent time zero (T0) N2O samples. From each chamber, after a 40-minute enclosure period (T40) one headspace sample was taken using a 50-ml syringe and 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 two chambers located on the highest N rate plots. A minimum of five samples were taken from each chamber at 15 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 where possible at the same time of day. 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, two 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. An exchange of samples of chamber air and standard gas mixtures between labs from the different research organisations involved in the NT26 programme who operated the GCs were carried out, to avoid the possibility of any bias in the results towards high or low values. Following fertiliser application, N2O flux measurements were carried out daily for the first 3 days, changing successively to 2-day intervals, then twice per week, and then weekly after the return of fluxes to the control level, continuing 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.70 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.

Data preparation and processing activities

Nitrous oxide fluxes from the two replicate chambers per plot were averaged. Cumulative fluxes were calculated using the trapezoidal rule to interpolate fluxes between sampling points.

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