EGU2020-18732
https://doi.org/10.5194/egusphere-egu2020-18732
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Flux fields affect the spatial distribution of phosphorus in a tilled loamy soil

Stefan Koch, Henrike Lederer, Petra Kahle, and Bernd Lennartz
Stefan Koch et al.
  • University of Rostock, Faculty for Agricultural and Environmental Sciences, Chair for Soil Physics, Germany (stefan.koch4@uni-rostock.de)

Heterogenous flow pathways through the soil are a major component in the transport of water, dissolved and particle-bound nutrients like phosphorus (P) to water resources, and promote the eutrophication of water bodies. Non-uniform water flow patterns may also influence the spatial variability of the P-content in soils.

This study was designed to understand the spatial distribution of P in agriculturally used soils and the mechanism causing P accumulation and depletion at the centimeter scale. We conducted three replicate dye tracer experiments using Brilliant Blue on a loamy Stagnosol in North-Eastern-Germany. The plant-available phosphorus of stained and unstained areas was analyzed using double lactate extraction and diffusive gradients on thin films (DGT).

The DL-extractable P and the DGT-extractable P were strongly correlated (p<0.001, R²=0.63) confirming that DL-P is a good measure for the mobile phase of soil phosphorus.

The plant available P contents of the topsoil were significantly higher than those of the subsoil in all three replicates. The topsoil’s stained areas showed higher P contents than unstained areas, while the opposite was found for the subsoil. The P contents varied strongly over the soil profiles (0.4 to 11.2 mg P 100 g-1) and different categories of flow patterns (matrix flow, flow fingers, preferential flow and no flow). The P contents of these flow patterns differed significantly from each other and followed the order: Pmatrix flow > Pfinger flow > Pno flow > Ppreferential flow.

We conclude that P tends to accumulate along flow pathways in managed and tilled topsoils, while in subsoils at a general lower P level, P is depleted from the prominent preferential flow domains. It is likely, that P in the shallow groundwater origins from preferred flow zones from the subsoil.

How to cite: Koch, S., Lederer, H., Kahle, P., and Lennartz, B.: Flux fields affect the spatial distribution of phosphorus in a tilled loamy soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18732, https://doi.org/10.5194/egusphere-egu2020-18732, 2020

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