Evaluation of Plant Growth-Promoting Rhizobacteria on Stockpiled Bermudagrass

Abstract

A two-year, small-plot study was conducted to evaluate plant growth-promoting rhizobacteria (PGPR) as an alternative form of N fertilization for fall-stockpiled bermudagrass. Eighteen 1-m2 Coastal bermudagrass plots were mowed to a 2.5-cm stubble height prior to stockpiling. Experimental treatments included a negative control, synthetic fertilizer, DH44, DH44 + fertilizer, Blend 20, and Blend 20 + fertilizer (n = 3). Two applications of PGPR were applied at the beginning of each stockpiling season in August and again 30 d later. Ammonium sulfate was applied at a rate of 56 kg N ha-1 concurrent with the first PGPR application. One-third of each plot was clipped to a height of 2.5 cm in mid-November, December, and January of each year to determine forage dry matter (DM) yield and nutritive value. Forage DM yield was greatest for Blend 20 + fertilizer, but it was not different (P = 0.2552) from that of the synthetic fertilizer treatment. Concentration of CP was least (P  0.0437) for DH44 and Blend 20 treatments. Concentrations of NDF and ADF were similar among all treatments, except for the negative control. In vitro true digestibility was not different (P < 0.05) among treatments. Yield and nutritive value parameters were greater in Year 2 than Year 1. These results indicate that PGPR are a viable option for biofertilization; however, further investigation into the effect of PGPR inoculants on a larger scale is needed.