Mobility of poultry litter phosphorus in a coastal plain forest soil

Document Type

Article

Publication Date

1-1-2015

Abstract

Loss of phosphorus (P) to surface waters from forest soils fertilized with P-rich poultry litter (PL) is likely less than P loss from pasture because forest soils are typically lower in P. This study examined Pmobility where PL was applied to forest soil in amounts constituting disposal. Triplicate plots (13.4 × 3.1 m) of 4-year-old loblolly pine (Pinus taeda) were amended once per year at 0, 5, 10, and 20 Mg PL/ha in 1996 and 1997-2001. Surface soil (0-15 cm) P was monitored annually during the application period and at varying frequencies until 2013. Cores to 1 m were taken in 2002 and 2013. Phosphate sorption in surface and subsoil was measured, and transport in surface soil was investigated. Sorption after 24 h followed the Langmuir model, which described retention during transport better than a linear model but not as well as a two-site kinetic Langmuir model with sorption capacity based on oxalate-extractable aluminum (Al) + iron (Fe). Phosphate sorption was least in 15-to 30-cm depth soil; sorption increased deeper into the Bt horizon. Neither the increase nor the decrease in surface soil P showed a clear effect of sorption nonlinearity. Treatment effects were significant to a depth of 45 cm in 2002 except for organic P (surface only). The profile distribution of P was generally consistent with sorption, with some evidence of preferential flow. Leaching from 2002 to 2013 was slow, moving P in 20-Mg ha-1 plots to 60 cm. However, leaching was likely increased by initial concentrations and fast relative to tree uptake.

Publication Source (Journal or Book title)

Soil Science

First Page

124

Last Page

133

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