Phosphorus Speciation in Long-Term Drained and Rewetted Peatlands of Northern Germany

Wakene Negassa,Dirk Michalik,Wantana Klysubun,Peter Leinweber

doi:10.3390/soilsystems4010011

Abstract

Previous studies, conducted at the inception of rewetting degraded peatlands, reported that rewetting increased phosphorus (P) mobilization but long-term effects of rewetting on the soil P status are unknown. The objectives of this study were to (i) characterize P in the surface and subsurface horizons of long-term drained and rewetted percolation mires, forest, and coastal peatlands and (ii) examine the influence of drainage and rewetting on P speciation and distributions using wet-chemical and advanced spectroscopic analyses. The total P was significantly (p < 0.05) different at the surface horizons. The total concentration of P ranged from 1022 to 2320 mg kg−1 in the surface horizons and decreased by a factor of two to five to the deepest horizons. Results of the chemical, solution 31P nuclear magnetic resonance (NMR), and P K-edge X-ray absorption near-edge structure (XANES) indicated that the major proportions of total P were organic P (Po). In the same peatland types, the relative proportions of Po and stable P fractions were lower in the drained than in the rewetted peatland. The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types.

Highlights

Peatlands can be a sink, source, and transformer of P, other essential plant nutrients, and pollutants that originate from agricultural soils, industrial, and urban waste [1]
The soil samples were collected from 0 to 80 cm soil depth and the sampling depths depending on the thickness of the accumulated peats, which ranged from 0.3 m to
The concentrations of total P and K were significantly higher in the surface than the subsurface horizons and decreased with depths (Table S1)

Summary

Introduction

Peatlands can be a sink, source, and transformer of P, other essential plant nutrients, and pollutants that originate from agricultural soils, industrial, and urban waste [1]. Drainage has contributed to peatland degradation in Europe and worldwide [2,3]. Such degraded peatlands can be a source of P that contributes to freshwater eutrophication by enhancing the growth of algae and other aquatic plants [4]. Rewetting agriculturally influenced peatlands increased the concentrations of soluble P as shown in a study across Europe [4]. High P mobilization at the inception of rewetting agriculturally influenced peatland perhaps can be transient since soluble P is

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Conclusion