Tuesday, November 14, 2006

Effects of Pine Straw Raking and Fertilization on Runoff Water Quality.

William Felicien, Lewis Gaston, Darren Cooper, Steven Hotard, and Michael Blazier. LSU AgCenter, Dept of Agronomy and Environmental Management, 104 Sturgis Hall, Baton Rouge, LA 70803

Annual pine straw harvest offers additional income for small landowners. However, this practice disrupts nutrient cycling and fertilizer amendment is needed to offset depletion in surface soil fertility. A plot study comparing straw harvest without fertilization, with inorganic fertilization and organic (poultry litter) fertilization to control was established in 2002 on a Ruston (fine-loamy, siliceous, thermic Typic Paleudult) soil. Baseline and subsequently annual surface (0 15 cm) soil samples were collected prior to fertilizer application. Runoff plots (1 m x 1 m) were installed in replicate plots and runoff from simulated rainfall collected prior to fertilizer application. Soil samples indicate that chemical fertility has been adequately maintained by replenishment with inorganic and poultry litter fertilizer, however, with increase in soil P, particularly where poultry litter was used. Losses of P in runoff were variable within treatments but generally paralleled increased soil P concentrations. Approximately 80 % of the P in runoff was molybdate- reactive. Use of simple Langmuir isotherms for P desorption into runoff adequately described P losses in most cases.