Performance of Bahiagrass Varieties Under Low-N Input Systems.

Bahiagrass (Paspalum notatum Flüggé) is the dominant forage species cultivated in Florida. It covers over 1 million ha in the state and it is well adapted to low input systems. Some grasses are capable of fixing atmospheric-N₂ in association with free-living bacteria. This study aimed to investigate theperformance of bahiagrass varieties under low-N input (no N fertilizer applied). Response variables measured included biological N₂-fixation potential, herbage accumulation, nutritive value, and belowground responses of six entries of bahiagrass. The study was performed in a randomized complete bock design with four replications during 2014, 2015, and 2016. Treatments were six entries of bahiagrass: Argentine, Pensacola, UF Riata, Sand Mountain, Tifton 9, and TifQuik. Five harvests were made each year at 5-cm stubble height to estimate herbage responses. After the last harvest of each year, two 0- to 20-cm depth x 10.8-cm diameter soil cores were taken to estimate belowground responses. Differences in herbage accumulation (HA) occurred and were greater from May through July of the second year. Argentine bahiagrass resulted in lower HA (P<0.05) than Sand Mountain, Tifton 9, and TifQuik, but similar to UF Riata and Pensacola bahiagrass, at the June/July harvest. Herbage accumulation declined 50% from 2014 (715 kg DM ha^-1 harvest^-1) to 2015 (350 kg DM ha^-1 harvest^-1). Herbage crude protein (CP) concentration was similar among bahiagrass entries, ranging from 69 to 75 g kg^-1. Belowground biomass increased from 14000 to 31100 kg DM ha^-1, from 2014 to 2015, respectively. Biological N₂ fixation and % N₂ derived from the atmosphere will still be analyzed.