Estimating dissolved reactive phosphorus concentration in surface runoff water from major Ontario soils

Wang, Y.T., Zhang, T.Q., Hu, Q.C., Tan, C.S., O'Halloran, I.P., Drury, C.F., Reid, D.K., Ma, B.L., Ball-Coelho, B., Lauzon, J.D., Reynolds, W.D., Welacky, T. (2010). Estimating dissolved reactive phosphorus concentration in surface runoff water from major Ontario soils, 39(5), 1771-1781. http://dx.doi.org/10.2134/jeq2009.0504

Abstract

Phosphorus (P) loss from agricultural land in surface runoff can contribute to eutrophication of surface water. This study was conducted to evaluate a range of environmental and agronomic soil P tests as indicators of potential soil surface runoff dissolved reactive P (DRP) losses from Ontario soils. The soil samples (0-to 20-cm depth) were collected from six soil series in Ontario, with 10 sites each to provide a wide range of soil test P (STP) values. Rainfall simulation studies were conducted following the USEPA National P Research Project protocol. The average DRP concentration (DRP30) in runoff water collected over 30 min after the start of runoff increased (p < 0.001) in either a linear or curvilinear manner with increases in levels of various STPs and estimates of degree of soil P saturation (DPS). Among the 16 measurements of STPs and DPSs assessed, DPSM3-2 (Mehlich-3 P/[Mehlich-3 Al + Fe]) (r2 = 0.90), DPSM3-3 (Mehlich-3 P/Mehlich-3 Al) (r2 = 0.89), and water-extractable P (WEP) (r 2 = 0.89) had the strongest overall relationship with runoff DRP 30 across all six soil series. The DPSM3-2 and DPS M3-3 were equally accurate in predicting runoff DRP30 loss. However, DPSM3-3 was preferred as its prediction of DRP 30 was soil pH insensitive and simpler in analytical procedure, if a DPS approach is adopted. Copyright © 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.