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Phosphorus Pool Composition in Soils and Sediments of Transitional Ecotones under the Influence of Agriculture
Author(s) -
Neidhardt Harald,
Achten Florian,
Kern Simon,
Schwientek Marc,
Oelmann Yvonne
Publication year - 2019
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2019.01.0012
Subject(s) - ecotone , sediment , soil water , fractionation , phosphorus , buffer strip , environmental chemistry , ecological succession , chemistry , hydrology (agriculture) , ecology , nutrient , environmental science , soil science , geology , agriculture , geomorphology , biology , geotechnical engineering , organic chemistry , shrub
Transitional ecotones such as vegetated buffer strips, stream banks, and streambeds retain phosphorus (P) in the immediate surroundings of farmland. Yet the fate of P in these ecotones remains unclear. Our objectives were to (i) test the difference in the P pool composition of soil and sediment between sites surrounded by agriculture and forestry and (ii) test whether specific P pools differ among transitional ecotones. Phosphorus pools (by a modified Hedley fractionation scheme) and the degree of P saturation (DPS) were determined in 33 soil and sediment samples from eight farmland and three forest sites. At farmland sites, total P in soil and sediment was more than twofold higher as compared to forestry sites. The proportion of labile inorganic P (Pi) and the DPS were significantly larger in transitional ecotones close to farmland. We further used normalized values for comparing the respective ecotones at the sites. The deviation of each transitional ecotone relative to the respective site average revealed that the normalized total P concentration and proportions of labile and moderately labile Pi were significantly smaller in bed sediment adjacent to farmland as compared to respective stream bank and buffer strip soil, whereas the stable Ca‐Pi proportion was larger. The results reflected a decreased Pi sorption capacity in combination with Pi desorption and transfer of Pi into secondary Ca‐Pi minerals in bed sediment. In summary, the influence of agriculture increases labile P pools in soil and sediment, which are then subject to a succession of dynamic processes resulting in a partial loss of Pi to the aqueous phase as well as fixation of Pi in the Ca‐Pi pool. Core Ideas Agriculture has a pronounced impact on P status and pools in transitional ecotones. Labile Pi and degree of P saturation significantly increased in buffer strips, stream banks, and beds. We found more Ca‐Pi but less labile P in streambeds than in stream banks and buffer strips. There is presumable transfer of labile P into the Ca‐Pi pool but also in the dissolved phase. Further knowledge of P pool changes is needed to manage legacy P in catchments.