Herbage and Animal Responses to Management Intensity of Continuously Stocked Bahiagrass Pastures

There are about 1 million ha of bahiagrass (Paspalum notatum Flugge) pasture in Florida. Rapid population growth is reducing grassland area and may force beef cattle (Bos taurus) producers to achieve economic livelihood on less land. One alternative is to increase management intensity of existing pasture. This research evaluated management intensity effects on beef heifer and bahiagrass pasture performance. Management intensities were low (40 kg N ha^-1 yr^-1, 1.4 animal units [AU, one AU = 500 kg live weight] ha^-1 stocking rate [SR]), moderate (120 kg N ha^-1 yr^-1, 2.8 AU ha^-1 SR), and high (360 kg N ha^-1 yr^-1, 4.2 AU ha^-1 SR). Across 4 yr, herbage mass (3.42 vs. 2.95 Mg ha^-1) and allowance (4.8 vs. 1.4 kg forage kg^-1 animal weight) were greater for low than high intensity. Herbage accumulation (41 vs. 17 kg ha^-1 d^-1), crude protein (140 vs. 99 g kg^-1), and in vitro digestible organic matter (505 vs. 459 g kg^-1) were greater for high than low intensity. Heifer average daily gain was greater for low than high intensity (0.34 vs. 0.28 kg), but gain per hectare (GHA) increased from low to high intensity (101 to 252 kg). Nitrogen fertilizer cost per additional kilogram of GHA above low intensity was $0.76 for moderate and $2.01 for high intensity. Increasing management intensity increased bahiagrass herbage accumulation and nutritive value, but GHA did not increase sufficiently to compensate for the additional fertilizer cost, especially for high intensity. Therefore, if land limitations for cattle production become acute, use of more managementresponsive species than bahiagrass probably will be required.