Sward Responses of Bahiagrass Cultivars under No Nitrogen Fertilization

ABSTRACT Bahiagrass (Paspalum notatum Flüggé) is the base of cow‐calf operations in Florida. Nitrogen is usually the most limiting mineral in pasture‐based systems. Various bahiagrass cultivars have been released over the years; however, an evaluation of their performance under no N fertilization has not been reported. There is some evidence that bahiagrass can associate with free‐living bacteria and fix atmospheric N2. This study investigated the performance and potential biological N2 fixation (BNF) of six bahiagrass cultivars (‘Argentine’, ‘AU Sand Mountain’, ‘Pensacola’, ‘TifQuik’, ‘Tifton‐9’, and ‘UF‐Riata’) under no N fertilization during the growing seasons of 2014, 2015, and 2016. Results showed no differences among cultivars for total herbage accumulation (2835 kg dry matter ha−1), total N aboveground (28 kg N ha−1 yr−1), and BNF (9 kg N ha−1 yr−1). Pensacola had greater crude protein than Tifton‐9 (84 vs. 78 g kg−1, respectively), whereas AU Sand Mountain had greater in vitro digestible organic matter (494 g kg−1) than other cultivars, except for Argentine. Argentine had greater root‐rhizome mass (24,914 kg organic matter ha−1) than UF‐Riata and TifQuik (15,367 and 14,682 kg organic matter ha−1, respectively). Carbon and N stocks in belowground biomass were greater in Argentine (8575 and 155 kg ha−1, respectively) than UF‐Riata (4514 and 85 kg ha−1, respectively). Root‐rhizome/shoot ratio averaged 37 across cultivars. Managing bahiagrass cultivars under no N fertilization inhibits the cultivar herbage potential; however, cultivar differences in nutritive value and root‐rhizome responses can still be detected.