Bahiagrass-Perennial Peanut Mixtures As an Alternative to Attenuate Nitrogen Fertilization in Hay Fields.

Legumes are capable of naturally fixing atmospheric N through association with rhizobia bacteria. Therefore, mixing legumes and grasses in a production system may decrease the need for N fertilization. The current study evaluated the performance of bahiagrass (Paspalum notatum Flüggé)-rhizoma peanut (Arachis glabrata Benth.) mixtures compared with monocultures. Eight treatments were allocated in a randomized block design with three replicates. Treatments consisted of two bahiagrass entries (‘Argentine’ and and an experimental dwarf; DF9); which received 90 kg N ha^-1 after each harvest, two rhizoma peanut entries (Ecoturf and an experimental entry; Q6B), and the mixture of each bahiagrass with each rhizoma peanut. The plots were harvested every 6 wk to a stubble of 7.5 cm. Response variables included herbage mass, botanical composition, in vitro digestibility (IVOMD), and crude protein (CP). Treatment (P < 0.001), harvest (P < 0.001) and treatment × harvest (P < 0.001) differences were significant for herbage mass, with mixtures being more productive than monocultures. The percentage of rhizoma peanut in harvested biomass was greatest in the Q6B/DF9 mixture (51%) and least in the Ecoturf/Argentine mixture (29%) throughout the season. There was no difference in IVOMD between the fertilized Argentine that mixed with Ecoturf (P = 0.1456) or Q6B (P = 0.1487). The IVOMD (410 g kg^-1) was unchanged when DF9 was fertilized (monoculture) or mixed with rhizoma peanut. For both bahiagrass entries, CP was greater when N fertilizer was added, compared to the grass portion of the mixtures. Rhizoma peanut IVOMD was similar (P > 0.05) comparing pure stands and mixtures; however, the rhizoma peanut CP declined (P < 0.05) when planted in mixtures. Growing rhizoma peanut together with bahiagrass improved total forage yield while reducing the need for commercial N fertilizer inputs, but there was limited effect on herbage nutritive value.