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Phosphorus Adsorption and Desorption Potential of Stream Sediments and Field Soils in Agricultural Watersheds
Author(s) -
Agudelo Sandra C.,
Nelson Nathan O.,
Barnes Philip L.,
Keane Timothy D.,
Pierzynski Gary M.
Publication year - 2011
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/jeq2010.0153
Subject(s) - soil water , manure , environmental science , hydrology (agriculture) , water quality , sediment , base flow , surface runoff , phosphorus , environmental chemistry , sorption , chemistry , adsorption , soil science , agronomy , geology , ecology , drainage basin , cartography , organic chemistry , geography , paleontology , geotechnical engineering , biology
Phosphorus release from stream sediments into water could increase P loads leaving agricultural watersheds and contribute to lag‐time between implementation of best management practices and improvement in water quality. Improved understanding of P release from stream sediments can assist in setting water quality goals and designing stream monitoring programs. The objective of this study was to estimate the relative potential of sediments and soils to release P to stream water in two agricultural watersheds. Stream sediments were collected from banks, pools, riffles, and depositional features. Soils were sampled from wheat, row crop, pasture, and manure‐amended fields. Sediments and soils were analyzed for equilibrium P concentration at zero net P sorption (EPC 0 ), maximum P adsorption capacity (P max ), anion exchange extractable P (P lab ), and degree of P saturation. Dissolved reactive P (DRP) of stream water was monitored. Stream sediment EPC 0 was similar to or less than EPC 0 from field soils; however, P lab of stream sediments was three times less than field soils. Sediments were sandy and had low P max due to low oxalate‐extractable Fe and Al, which could be explained by stream geomorphology. Manure‐amended fields had the highest EPC 0 and P lab due to continued inputs of manure‐based P; however, conventionally fertilized fields also represented an important P source due to their vast extent. Stream water DRP was similar to EPC 0 of stream sediments during base flow and similar to EPC 0 of field soils during storm flow. These results indicate that sediments in these streams are a relatively minor P source.