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Estimating Runoff Phosphorus Losses from Calcareous Soils in the Minnesota River Basin
Author(s) -
Fang F.,
Brezonik P. L.,
Mulla D. J.,
Hatch L. K.
Publication year - 2002
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/jeq2002.1918
Subject(s) - surface runoff , environmental science , calcareous , phosphorus , soil water , hydrology (agriculture) , calcareous soils , drainage basin , geology , soil science , geography , geotechnical engineering , ecology , chemistry , organic chemistry , biology , paleontology , cartography
Bioavailable phosphorus (BAP) in stormwater runoff is a key issue for control of eutrophication in agriculturally impacted watersheds. Laboratory experiments were conducted in soil runoff boxes to determine BAP content in simulated storm runoff in 10 (mostly) calcareous soils from the Minnesota River basin in southern Minnesota. The soluble reactive phosphorus (SRP) portion of the runoff BAP was significantly correlated with soil Mehlich‐III P, Olsen P, and water‐extractable P (all r 2 > 0.90 and p < 0.001). A linear relationship ( r 2 = 0.88, p < 0.001) also was obtained between SRP in runoff and the phosphorus saturation index based on sorptivity (PSI s ) calculated with sorptivity as a measure of the inherent soil P sorption capacity. Runoff levels of BAP estimated with iron oxide–impregnated paper were predicted well by various soil test P methods and the PSI s of the soils, but correlation coefficients between these variables and runoff BAP were generally lower than those for runoff SRP. Using these relationships and critical BAP levels for stream eutrophication, we found corresponding critical levels of soil Mehlich‐III P and Olsen P (which should not be exceeded) to be 65 to 85 and 40 to 55 mg kg −1 , respectively.