Composition and decomposition of rhizoma peanut (Arachis glabrata benth) belowground biomass

Authors: SANTOS, ERICK - University Of Florida; DUBEUX, JOSE - University Of Florida; MACKOWIAK, CHERYL - University Of Florida; SOLLENBERGER, LYNN - University Of Florida; Jaramillo, David; VAN CLEEF, FLAVIA - University Of Florida; LONGHINI, VANESSA - University Of Florida; GROSSI, BRUNO - Embrapa; GARCIA, LIZA - University Of Florida; DANTAS, LUANA - University Of Florida; ZAGATO, LUANA - University Of Florida; SIQUEIRA, MICHELLE - University Of Florida

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2022
Publication Date: 6/15/2022
Citation: Santos, E., Dubeux, J., Mackowiak, C., Sollenberger, L., Jaramillo, D.M., Van Cleef, F., Longhini, V., Grossi, B., Garcia, L., Dantas, L., Zagato, L., Siqueira, M. 2022. Composition and decomposition of rhizoma peanut (Arachis glabrata benth) belowground biomass. Agronomy Journal. Article 9967. https://doi.org/10.1038/s41598-022-14001-7.
DOI: https://doi.org/10.1038/s41598-022-14001-7

Interpretive Summary: Relative to herbage responses, few studies have evaluated root-rhizome dynamics of warm-season perennial forages under different management practices. We evaluated root-rhizome responses and decomposition dynamics of a perennial legume [Rhizoma peanut (Arachis glabrata Benth.)] under grazing (grazed) or at 56-d harvest intervals (not grazed), simulating hay-harvest intervals. In the drier year (2019), root-rhizome mass was greater for non-grazed in two out of three harvest periods. In 2019, both biomass and nitrogen relative decay rates were greater for grazed than non-grazed sites. Considering 30% of RP in the pasture, roots and rhizomes can contribute 12 to 21 kg N/ha per season. Root-rhizome dynamics of RP are affected by defoliation management; however, such responses are more likely to occur during drier years.

Technical Abstract: Relative to herbage responses, there are few studies evaluating root-rhizome dynamics of warm-season perennial forages under different management practices. We evaluated root-rhizome responses and decomposition dynamics of a perennial legume [Rhizoma peanut (RP; Arachis glabrata Benth.)] under grazing (grazed) or at 56-d harvest intervals (not grazed). Exclusion cages were used to prevent grazing and they were paired with a grazed site. Three 56-d growth periods were evaluated in 2018 and 2019. In the drier year (2019), root-rhizome mass was greater for non-grazed in two out of three occasions, reaching its maximum at 14980 kg OM ha-1. Conversely, root-rhizome N concentration was lesser for non-grazed than grazed in 2019 (12 vs 14 g kg-1). Root-rhizome growth rate was greatest in 2018 compared to 2019 (18.0 vs. 10.5 kg OM ha-1 d-1). In 2019, both, biomass (0.0013 vs. 0.0010 g g-1 d-1) and N relative decay rates (0.0016 vs. 0.0011 g g-1 d-1) were greater for grazed than non-grazed. Root-rhizome N for 2018 and 2019 were 159 and 192 kg N ha-1, whereas remaining N was 86% and 93%, respectively. Nitrogen disappearance was estimated to be 22.3 and 13.4 kg N ha-1 in a 56-d period, or 70 and 40 kg N ha-1 during the growing season (168 d). Considering 30% of RP in the pasture, roots and rhizomes contribute from 12 to 21 kg N ha-1 per season. Root-rhizome dynamics of RP are affected by defoliation management; however, such responses are more likely to occur in drier years.