Journal article

Authors list: Tenspolde, Arne; Kleineidam, Kristina; Müller, Christoph; Wrage-Mönnig, Nicole

Publication year: 2025

Pages: 421-435

Journal: Biology and Fertility of Soils

Volume number: 61

ISSN: 0178-2762

eISSN: 1432-0789

Open access status: Hybrid

DOI Link: https://doi.org/10.1007/s00374-023-01730-8

Publisher: Springer

Abstract: 
Isotopic tracer methods using N-15 or other isotopes provide insights into the sources and underlying N transformations leading to N2O emissions from agricultural soils. However, homogeneous labelling of naturally structured soil in the field is challenging since macropore flow must be avoided while the application must be performed in a limited timeframe. Therefore, we tested the infiltration pattern of several application methods and consequently developed drip application (DA) for larger scales using individual dropper bottles. We performed a proof of concept test, followed by an evaluation experiment in-situ with a manual sprinkler as control at an undisturbed grassland site using (NH4NO3)-N-15-N-15 (80 kg N ha(-1), 10 at.%, 15 mm precipitation equiv.). N-15-NH4+ and N-15-NO3- recovery rates and corresponding correlation coefficients were calculated to examine horizontal and vertical homogeneity. The proof of concept test showed the negative effect of very dry topsoil on homogeneous infiltration. DA achieved significantly larger N-15 recovery rates than sprinkler application and led to a more homogeneous horizontal label distribution. For DA, coefficients of variation of N-15 recovery rates were smaller than with sprinklers for most depths, yet for both methods N-15 recovery rates especially of N-15-NH4+ decreased vertically. Besides optimised label distribution, the DA method offers high flexibility in application patterns while offering reproducibility, feasibility and a reasonable application speed also at undisturbed sites at the plot scale. Moreover, DA causes no change in soil structure or soil diffusivity. Thus, the drip application method was found suitable for tracer application to field sites.

Harvard Citation style: Tenspolde, A., Kleineidam, K., Müller, C. and Wrage-Mönnig, N. (2025) Application of isotopic labels optimised for large scale plot experiments, Biology and Fertility of Soils, 61, pp. 421-435. https://doi.org/10.1007/s00374-023-01730-8

APA Citation style: Tenspolde, A., Kleineidam, K., Müller, C., & Wrage-Mönnig, N. (2025). Application of isotopic labels optimised for large scale plot experiments. Biology and Fertility of Soils. 61, 421-435. https://doi.org/10.1007/s00374-023-01730-8