ORIGINAL ARTICLE
Agronomic and environmental impacts of phosphorus fertilization of low input bahiagrass systems in Florida
Augustine K.Obour •Maria L.Silveira •
Joao M.B.Vendramini •Lynn E.Sollenberger •
George A.O’Connor •James W.Jawitz
Received:11May 2010/Accepted:30July 2010/Published online:19August 2010ÓSpringer Science+Business Media B.V.2010
Abstract Phosphorus management in low input bahiagrass (Paspalum notatum Flugge)systems rep-resents a major challenge of agronomic and environ-mental importance.Concerns over agricultural P transport to surface waters have prompted several revisions in the P fertilizer recommendations for bahiagrass in Florida.This study evaluated the effects of revised P fertilizer recommendations on forage dry matter yield (DMY)and nutritive value and the potential impacts on water quality in bahiagrass pastures growing on a Spodosol.Treatments con-sisted of the factorial combination of three N rates (0,56,and 112kg N ha -1)and four P rates (0,5,10,and 20kg P ha -1),replicated three times and applied annually in May of 2007and 2008.Forage was harvested at 28-d intervals and DMY,tissue P and crude protein concentration,and P uptake were measured.To monitor P leaching potential,suction cup lysimeters were installed at 15-,30-,60-,90-,and
150-cm depths.In 2007,bahiagrass DMY was not affected by P;however,in 2008there was a linear increase in DMY from 6.9to 8.2Mg ha -1as P rate increased.In both years,tissue P increased linearly from 2.1to 2.5g kg -1as P rates increased from 0to 20kg P ha -1.Similarly,P uptake increased from 14kg P ha -1for the control to 19kg P ha -1for the treatment receiving 20kg P ha -1.During the 2-year study,P fertilization had no impact on soil Mehlich-1,water-extractable P,and leachate P concentrations.Leachate P concentrations at the 15-and 30-cm depths varied seasonally (from 0.05to 0.85mg P l -1),with greater spikes occurring during periods of high water table conditions.Current P fertilization recommenda-tion can increase bahiagrass DMY with no adverse impacts on water quality.
Keywords Leaching ÁPasture fertilization ÁSpodosol ÁWater quality
Introduction
Bahiagrass is the most widely planted perennial forage grass in Florida,occupying about 2million ha in the state (Muchovej and Mullahey 2000).Bahiagrass pastures are predominantly grown on Spodosols and are well adapted to the sandy soils of Florida.The grass tolerates low soil fertility conditions,low pH,and intermittent wet conditions and produces reasonable
A.K.Obour ÁM.L.Silveira (&)ÁJ.M.
B.Vendramini Range Cattle Research and Education Center,University of Florida,3401Experiment Station,Ona,FL 33865,USA e-mail:mlas@ufl.edu
L.E.Sollenberger
Agronomy Department,University of Florida,2185McCarty,Gainesville,FL 32611,USA
G.A.O’Connor ÁJ.W.Jawitz
Soil and Water Science Department,University
of Florida,106Newell Hall,Gainesville,FL 32611,USA
Nutr Cycl Agroecosyst (2011)89:281–290DOI 10.1007/s10705-010-9393-1
