Soil Phosphorus Translocation via Preferential Flow Pathways: A Comparison of Two Sites With Different Phosphorus Stocks

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Contributors

Abstract

Weather events where a dry period is followed by a heavy rainfall event appear to affect phosphorus (P) exports through preferential flow pathways from forest soils. Export rates also depend on the P stocks. To explore this, we installed zero-tension lysimeters in three trenches at two sites with contrasting soil P stocks. Lysimeters were installed in three different depths (topsoil, subsoil and deep subsoil) to explore P depth transport. We covered the forest floor above the lysimeters with tarpaulins to simulate a dry period and afterward artificially irrigated the area. This experiment was repeated three times at each site. Lysimeter samples were analyzed for concentrations of total P, organic and inorganic dissolved P and particle bound P (>0.45 μm). Loads of P and flow rates were calculated. Results reveal clear differences between sites, individual events and soil depths. At both sites, concentrations and loads of P in the topsoil lysimeters were higher than those in the subsoil. This difference was most evident at the low P site and underlines its efficiency of recycling nutrients. Dissolved inorganic P showed marked peaks in the topsoil lysimeters, whereby in the subsoil, particle-bound P peaks were partly noticeable at both sites. Depth transport of P into the subsoil depended on initial soil moisture, texture and the spatial distribution of flow pathways. Further, we observed large heterogeneity within a single site, dependent on profile-specific characteristics of the distribution of P, flow pathways and microbial biomass. We conclude that under certain conditions, there is a depth transport of P into the subsoil and therefore a potential of P exports, especially for particle-bound P. Small-scale heterogeneity hampers the clear identification of influences and illustrates the need for further research regarding soil heterogeneity.

Details

Original languageEnglish
Article number48
JournalFrontiers in Forests and Global Change
Volume3
Publication statusPublished - 5 May 2020
Peer-reviewedYes

External IDs

ORCID /0000-0001-8948-1901/work/168717645

Keywords

Keywords

  • dry period, forest soil, heavy rainfall event, P loads, zero-tension lysimeter