Nitrogen isotope enrichment factor as an indicator of denitrification potential in top and subsoil in the Apače Valley, Slovenia
Marina Pintar A D , Spela Velikonja Bolta B and Franc Lobnik CA University of Ljubljana Biotechnical Faculty, Agronomy Department, Centre for Agricultural Land Management and Agrohydrology, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
B Agricultural Institute of Slovenia, Hacquetova 17, 1000 Ljubljana, Slovenia.
C University of Ljubljana Biotechnical Faculty, Agronomy Department, Centre for Soil and Environmental Science, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
D Corresponding author. Email: marina.pintar@bf.uni-lj.si
Australian Journal of Soil Research 46(8) 719-726 https://doi.org/10.1071/SR07123
Submitted: 23 August 2007 Accepted: 11 September 2008 Published: 2 December 2008
Abstract
Denitrification is still a poorly explained process in soil nitrogen cycles. Nitrogen isotope analyses, in combination with conventional soil-science methods (i.e. rate measurements), permit the tracing and quantification of several turn-over and transfer processes in soils. The aim of the presented investigations is to determine the 15N isotope enrichment factor (ε) in a laboratory experiment during denitrification in the topsoil and subsoil layer of a Eutric Fluvisol (FAO classification) from the Apače Valley (NE Slovenia). Intact soil cores taken from depths of 0.10–0.20 m and 0.90–1.00 m were incubated under anaerobic conditions at a temperature of 18°C. A nitrate dose of 116 mg N-NO3/L was added to the topsoil layer and 58 mg N-NO3/L to the subsoil material. Glucose (250 mg) was added to each soil column. After the initial 24 h of incubation, water samples were taken every 8 h. The isotope enrichment factor for denitrification in the upper soil-layer columns was –7.60 ± 1.28‰ and for subsoil columns –34.91 ± 1.77‰ (n = 3). The isotope enrichment factor close to zero demonstrated that microorganisms easily consumed abundant substrate in the topsoil layer. Added nitrate and glucose exceeded the capacity of the microbial population in the subsoil and the process was limited by a low microbial population for which a high ε is characteristic.
Additional keywords: isotopes, soil column experiment.
Acknowledgments
We appreciate the constructive reviews of the draft manuscript provided by the four anonymous reviewers and special thanks for those under code four.
Barkle G,
Clough T, Stenger R
(2007) Denitrification capacity in the Vadose Zone at three sites in the Lake Taupo Catchment, New Zealand. Australian Journal of Soil Research 45, 91–99.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
(Accessed 27 Sept. 2000)
Stevens RJ, Laughlin RJ
(1998) Measurement of nitrous oxide and di-nitrogen emissions from agricultural soils. Nutrient Cycling in Agroecosystems 52, 131–139.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Stoate C,
Boatman ND,
Borralho RJ,
Rio Carvalho C,
de Snoo GR, Eden P
(2001) Ecological impacts of arable intensification in Europe. Journal of Environmental Management 63, 337–365.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
PubMed |
Thayalakumaran T,
Bristow KL,
Charlesworth PB, Fass T
(2008) Geochemical conditions in groundwater systems: Implications for the attenuation of agricultural nitrate. Agricultural Water Management 95, 103–115.
| Crossref | GoogleScholarGoogle Scholar |
van Cleemput O
(1998) Subsoils: chemo- and biological denitrification, N2O and N2 emissions. Nutrient Cycling in Agroecosystems 52, 187–194.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
van der Salm C,
Dolfing J,
Heinen M, Velthof GL
(2007) Estimation of nitrogen loss via denitrification from heavy clay soil under grass. Agriculture, Ecosystems and Environment 119, 311–319.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Well R,
Höper H,
Mehranfar O, Meyer K
(2005) Denitrification in the saturated zone of hydromorphic soils-laboratory measurements, regulating factors and stochastic modeling. Soil Biology & Biochemistry 37, 1822–1836.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
White DC,
Stair JO, Ringelberg DB
(1996) Quantitative comparisons of in situ microbial biodiversity by signature biomarker analysis. Journal of Industrial Microbiology 17, 185–196.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Xue Y,
Kovacic DA,
David MB,
Gentry LE,
Mulvaney RL, Lindau CW
(1999) In situ measurements of denitrification in constructed wetlands. Journal of Environmental Quality 1, 263–269.
Zahn MT, Grimm WD
(1993) Nitrate and chloride loadings as anthropogenic indicators in the groundwater of an Alp foothills region in the Upper Bavaria, FRG. Water and Soil Pollution 68, 469–483.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Zelles L,
Bai QY,
Ma RX,
Rackwitz R,
Winter K, Besse F
(1993) Microbial biomass, metabolic activity and nutritional status determined from fatty acid patterns and poly-hydroxybutyrate in agriculturally-managed soils. Soil Biology & Biochemistry 26, 439–444.
| Crossref | GoogleScholarGoogle Scholar |
