Water footprint, herbage, and livestock responses for nitrogen-fertilized grass and grass–legume grazing systems

Authors: Jaramillo, David; DUBEUX, JOSE - University Of Florida; SOLLENBERGER, LYNN - University Of Florida; VENDRAMINI, JOAO - University Of Florida; MACKOWIAK, CHERYL - University Of Florida; DILORENZO, NICOLAS - University Of Florida; GARCIA, LIZA - University Of Florida; QUEIROZ, LUANA - University Of Florida; SANTOS, ERICK - University Of Florida; HOMEM, BRUNO - University Of Florida; VAN CLEEF, FLAVIA - University Of Florida; RUIZ-MORENO, MARTIN - University Of Florida

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2021
Publication Date: 6/28/2021
Citation: Jaramillo, D.M., Dubeux, J., Sollenberger, L., Vendramini, J., Mackowiak, C., Dilorenzo, N., Garcia, L., Queiroz, L., Santos, E., Homem, B., Van Cleef, F., Ruiz-Moreno, M. 2021. Water footprint, herbage, and livestock responses for N-fertilized grass and grass-legume grazing systems. Crop Science. https://doi.org/10.1002/csc2.20568.
DOI: https://doi.org/10.1002/csc2.20568

Interpretive Summary: Replacing N fertilizer with forage legumes may increase sustainability of grazing systems. The objectives were to evaluate herbage and animal responses and to quantify the water footprint associated with beef production in N-fertilized grass or grass-legume systems during 4 years under continuous stocking. The three year-round forage systems were: 1) Grass+N which included N-fertilized bahiagrass (Paspalum notatum Flüggé) during summer, and it was overseeded with N-fertilized cereal rye (Secale cereale L.) and oat (Avena sativa L.) during winter; 2) Grass+Clover included bahiagrass without N fertilizer during summer, and it was overseeded with rye, oat, and a mixture of clovers (Trifolium spp.) during winter; and 3) Grass+Clover+RP included rhizoma peanut (Arachis glabrata Benth.)-bahiagrass mixture during summer, and it was overseeded with a similar rye-oat-clover mixture as for Grass+Clover. Clover inclusion improved uniformity of herbage distribution throughout the winter. Including rhizoma peanut increased cattle average daily gain (ADG) by 74% during summer. The ADG in Grass+Clover+RP was 0.61 kg d-1 compared with 0.35 kg d-1 on Grass+N and Grass+Clover. The water footprint during summer was less in Grass+Clover+RP than Grass+Clover (18 and 25 m3 kg-1 bodyweight, respectively). Gain per area (GPA) was similar across all treatments through the year, indicating similar productivity in grass-legume and N-fertilized grass systems. The N-fertilizer inputs were reduced from 224 to 34 kg N ha-1 yr-1 in Grass+Clover+RP, compared to Grass+N. Inclusion of rhizoma peanut and clovers contributes to developing sustainable grazing systems with reduced levels of off-farm inputs.

Technical Abstract: Replacing N fertilizer with forage legumes may increase sustainability of grazing systems. The objectives were to evaluate herbage and animal responses and to quantify the water footprint associated with beef production in N-fertilized grass or grass-legume systems during 4 years under continuous stocking. The three year-round forage systems were: 1) Grass+N which included N-fertilized bahiagrass (Paspalum notatum Flüggé) during summer, and it was overseeded with N-fertilized cereal rye (Secale cereale L.) and oat (Avena sativa L.) during winter; 2) Grass+Clover included bahiagrass without N fertilizer during summer, and it was overseeded with rye, oat, and a mixture of clovers (Trifolium spp.) during winter; and 3) Grass+Clover+RP included rhizoma peanut (Arachis glabrata Benth.)-bahiagrass mixture during summer, and it was overseeded with a similar rye-oat-clover mixture as for Grass+Clover. Clover inclusion improved uniformity of herbage distribution throughout the winter. Including rhizoma peanut increased cattle average daily gain (ADG) by 74% during summer. The ADG in Grass+Clover+RP was 0.61 kg d-1 compared with 0.35 kg d-1 on Grass+N and Grass+Clover. The water footprint during summer was less in Grass+Clover+RP than Grass+Clover (18 and 25 m3 kg-1 bodyweight, respectively). Gain per area (GPA) was similar across all treatments through the year, indicating similar productivity in grass-legume and N-fertilized grass systems. The N-fertilizer inputs were reduced from 224 to 34 kg N ha-1 yr-1 in Grass+Clover+RP, compared to Grass+N. Inclusion of rhizoma peanut and clovers contributes to developing sustainable grazing systems with reduced levels of off-farm inputs.