Poultry Litter Phosphorus in a Louisiana Pasture: Enrichment, Losses, Remediation and Attenuation.

Build-up of soil phosphorus (P) over six years of poultry litter (PL) application at rates of 0, 5, 10 and 20 Mg/ha and its decline over the next 12 years was monitored at a pasture site in northern Louisiana, 1996 through 2013. Peak surface soil concentrations were about 1000 mg/kg, with evidence of leaching and high runoff losses. No more PL was applied after 2001, and active remediation by bermuda- and ryegrass harvest was begun 2002 and continued through 2005. Runoff loss by 2006 was substantially reduced. Surface concentration of P continued to decrease over next seven years and cores from 2013 showed further leaching.