Silvopasture Switchgrass Fertilized with Poultry Litter: Nutrient Removal, Soil Fertility, and Runoff Water Quality

ABSTRACT

Alternative use of poultry litter (PL) for forest rather than pasture fertilization would improve forest soil fertility and reduce nutrient build-up in pasture. Yield and nutrient uptake of Alamo switchgrass (Panicum virgatum L.) in a loblolly pine (Pinus taeda L.) silvopasture annually fertilized with PL or urea at 80 and 160 kg N ha⁻¹ for four years, and without fertilization were compared. Treatment effects on soil fertility and effect of PL on runoff water quality were also determined. Fertilization with N increased yields 120% to an average of 3.8 Mg ha⁻¹ yr⁻¹. Since nutrient removal was small, P, base cations and pH increased in the ≤30 cm depth soil with PL. Total P in edge-of-plot runoff was increased by 0.31 kg ha⁻¹ y⁻¹ at the higher PL rate. Two applications at this rate per tree rotation might be justified based on increased soil fertility and infrequently increased P load.

KEYWORDS:

• Silvopasture
• switchgrass
• loblolly pine
• poultry litter
• phosphorus
• soil fertility
• water quality

Acknowledgments

Historical aerial photographs were provided by J. Anderson (Cartographic Information Center, Department of Geography and Anthropology, LSU).

Additional information

Funding

This work was supported by the Louisiana Board of Regents under [LEQSF [2012-2015]-RD-A-01], with additional funding from the USDA-NIFA.