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The effect of soil phosphorus on particulate phosphorus in land runoff
Author(s) -
Withers P. J. A.,
Hartikainen H.,
Barberis E.,
Flynn N. J.,
Warren G. P.
Publication year - 2009
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2009.01161.x
Subject(s) - surface runoff , soil water , phosphorus , eutrophication , zoology , environmental chemistry , chemistry , sorption , saturation (graph theory) , arable land , silt , hydrology (agriculture) , environmental science , nutrient , soil science , ecology , biology , geology , paleontology , mathematics , geotechnical engineering , organic chemistry , adsorption , combinatorics , agriculture
Summary Accumulation of surplus phosphorus (P) in the soil and the resulting increased transport of P in land runoff contribute to freshwater eutrophication. The effects of increasing soil P (19–194 mg Olsen‐P (OP) kg −1 ) on the concentrations of particulate P (PP), and sorption properties ( Q max , k and EPCo) of suspended solids (SS) in overland flow from 15 unreplicated field plots established on a dispersive arable soil were measured over three monitoring periods under natural rainfall. Concentrations of PP in plot runoff increased linearly at a rate of 2.6 μg litre −1 per mg OP kg −1 of soil, but this rate was approximately 50% of the rate of increase in dissolved P (< 0.45 μm). Concentrations of SS in runoff were similar across all plots and contained a greater P sorption capacity (mean + 57%) than the soil because of enrichment with fine silt and clay (0.45–20 μm). As soil P increased, the P enrichment ratio of the SS declined exponentially, and the values of P saturation ( P sat ; 15–42%) and equilibrium P concentration (EPCo; 0.7–5.5 mg litre −1 ) in the SS fell within narrower ranges compared with the soils (6–74% and 0.1–10 mg litre −1 , respectively). When OP was < 100 mg kg −1 , P sat and EPCo values in the SS were smaller than those in the soil and vice‐versa, suggesting that eroding particles from soils with both average and high P fertility would release P on entering the local (Rosemaund) stream. Increasing soil OP from average to high P fertility increased the P content of the SS by approximately 10%, but had no significant ( P > 0.05) effect on the P sat , or EPCo, of the SS. Management options to reduce soil P status as a means of reducing P losses in land runoff and minimizing eutrophication risk may therefore have more limited effect than is currently assumed in catchment management.