Composition and decomposition of rhizoma peanut (arachis glabrata benth) belowground biomass
2022
Santos, Erick R. S. | Dubeux, Jose C. B. Jr | Sollenberger, Lynn | Siqueira, Michelle C. B. | Cleef, Flavia O. S. | Jaramillo, David M. | Zagato, Luana Q. S. D. | Ruiz-Moreno, Martin | Garcia, Carlos
Roots and rhizomes play an important role in nutrient cycling, however, few studies investigate how their decomposition pattern is affected by defoliation and time of the year. This 2-yr. study evaluated belowground litter composition and decomposition of a warm-season rhizomatous perennial legume, rhizoma peanut (RP; Arachis glabrata Benth.), managed either under continuous stocking or in 56-d harvest intervals A trial with 168 d of incubation was performed to estimate remaining biomass, remaining N, C:N ratio, acid detergent fiber (ADF), and acid detergent insoluble N (ADIN). Additionally, three 56-d incubations were performed to evaluate the disappearance coefficient (B0) and relative decay rate (k) along each year. There was no significant difference among treatments for the 168-d incubation period (P > 0.05). After 168 d, there was 21 and 60% left of the initial biomass and initial N, respectively. Relative decay rate for OM and N were 0.0088 and 0.0035 g g-1 d-1, respectively. Carbon-to-N ratio decreased from 29 at day 0 to 17 at day 168. Concentration of ADIN increased from 6.9 to 19.3 g kg-1, plateauing at day 79. The B0 and k for remaining OM and N were greater during the late season harvest interval than the early season harvest and could be explained by greater N concentration and lower C:N ratio. The rapid decomposition, difference in C:N ratio from day 0 to day 168, and the increase in ADIN indicate great amounts of root-rhizome soluble C at initial incubation. This data will be useful to estimate RP root-rhizome turnover and its contribution to grassland ecosystems.
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