Abstract
Abstract. At a cropland and a grassland site field scale ammonia (NH3) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. A consistency test with concentrations measured by impingers showed very low systematic deviations for the EC/HT-CIMS results (<8%) but larger deviations for the bLS/FTIR results. For both slurry application events, the period during fertilisation and the subsequent two hours contributed by more than 80% to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3% loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3% over the grassland field.
Highlights
The growing demand for food and energy products has lead to highly intensified agriculture with increasing emissions of nitrogen-containing compounds that pose environmental risks
Field scale NH3 emissions from slurry application were determined over a cropland and a grassland field by two different analytical approaches
The cumulated eddy covariance (EC)/high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and backward Lagrangian Stochastic (bLS)/Fourier Transform Infrared (FTIR) emissions agreed within 20 %, a difference typical for NH3 flux quantification
Summary
The growing demand for food and energy products has lead to highly intensified agriculture with increasing emissions of nitrogen-containing compounds that pose environmental risks. One of the important trace gas species in emissions associated with agriculture is ammonia (NH3) (Aneja et al, 2008). This anthropogenic NH3 release contributes to a large extent to the harmful effects of high reactive nitrogen loads (Galloway et al, 2003; Erisman et al, 2007). A detailed quantification of NH3 emissions with high accuracy is essential for a better knowledge about the factors controlling NH3 volatilisation after application of organic fertiliser (Erisman et al, 2008; Zhang et al, 2008). Such measurements are vital for the characterisation of the agricultural nitrogen budget (Ammann et al, 2009) as well as to link emissions and monitoring, and to assess abatement strategies (Bleeker et al, 2009; Erisman et al, 2009)
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