Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.1016/j.agee.2014.10.001
Titel (primär) Ammonia volatilisation is not the dominant factor in determining the soil nitrate isotopic composition of pasture systems
Autor Wells, N.S.; Baisden, W.T.; Clough, T.J.
Quelle Agriculture, Ecosystems & Environment
Erscheinungsjahr 2015
Department CATHYD
Band/Volume 199
Seite von 290
Seite bis 300
Sprache englisch
Keywords Nitrate; Grazed pastures; Ammonia volatilisation; Nitrogen mineralisation; Denitrification; Nitrification
UFZ Querschnittsthemen RU2;
Abstract Nitrate dual isotopes (δ15N—NO3- and δ18O—NO3-) are increasingly used to assess the sources and sinks
of nitrogen (N) pollution in freshwater systems. However, the application of this methodology to pasture
agroecosystems is currently limited by the lack of information on how, or even if, the primary N inputs to
the systems (livestock urine and urea fertiliser) are expressed in the isotopic signature of exported NO3-.
To remedy this gap, direct measurements of fractionation during ammonia volatilisation were linked
with changes in the concentration and isotopic composition of the residual soil inorganic N pool (NO3-,
nitrite, and ammonium) following the addition of differing levels of bovine urine and urea fertiliser.
Ammonia volatilisation, with a δ15N enrichment factor of +35±5‰, removed from 5 to 40% of N inputs
from the different treatments, which should have enriched the residual inorganic N pool to 25‰ and 3‰,
respectively. However, this fractionation did not propagate into the soil NO3- pool due to a combination
of urine-induced mineralisation (up to 120 mg N g soil-1 day-1 in the high urine treatment) and on-going
nitrification. Consequently, NO3- measured within the treatments was not as enriched in 15N as the
values typically ascribed to excreta-N sources. Up-scaling these results, the whole-pasture NO3- isotopic
composition primarily reflected time since fertilisation, regardless of urine inputs. These
necessitate expanding the range of δ15N—NO3- values ascribed to livestock sources to encompass values
as low as 10‰, highlighting the need to account for post-deposition soil N cycling in order to accurately
define NO3- isotopic source ranges.
dauerhafte UFZ-Verlinkung
Wells, N.S., Baisden, W.T., Clough, T.J. (2015):
Ammonia volatilisation is not the dominant factor in determining the soil nitrate isotopic composition of pasture systems
Agric. Ecosyst. Environ. 199 , 290 - 300 10.1016/j.agee.2014.10.001