Wednesday, November 15, 2006

Developing a Phosphorus Calibration Curve for Bahiagrass Pasture Fertilization.

Martin Adjei, University of Florida, 3401 Experiment Station, Ona, FL 33865-9706, United States of America, Johannes Scholberg, 304 Newell Hall, "PO Box 110500, Univ. of FL.", Gainesville, FL 32611-0500, United States of America, and John Rechcigl, Univ. of FL-Gulf Coast Res., 14625 County Rd. 672, 14625 County Rd. 672, Wimauma, FL 33598-6101, United States of America.

Very little information is available regarding the response of bahiagrass (Paspalum notatum) production to changes in soil P status.  An experiment was conducted  on Pomona fine sand (sandy, silicious, hyperthermic, Ultic Alaquod) in 2004 and  2005 to determine the effect of P fertilizer application (0, 5, 15 and 20  kg P ha-1 harvest-1) at N application rates of  67, 90 and 134 kg ha-1 harvest-1 on forage dry matter yield (DMY), nutritive value, tissue P and soil P status. The initial soil P was <10 mg kg-1. In 2004, DMY averaging 12.1 Mg ha-1 was independent of applied N or P but tissue P concentration varied from 1.7 to 2.3 g kg-1 with increasing P application.  In 2005, DMY increased linearly from 15.0 to 19 Mg ha-1 and tissue P curvilinearly from 1.5 to 3.0 in response to applied P.  Forage crude protein concentration (130 to 146 g kg-1) responded positively to both applied N and P in 2 yr but their effect on IVOMD was significant only in 2004 (446 to 465 g kg-1).  Current results seem to validate the 67 kg N ha-1 IFAS fertilizer recommendation and previous reports that bahiagrass requires minimum P input for optimum forage production. Tissue P could provide a useful model for monitoring bahiagrass growth performance in hay production.