Signal Grass Litter Decomposition Rate Increases with Inclusion of Calopo Academic Article uri icon


  • Low N availability is a major limitation in tropical and subtropical pasture systems and one of the main causes for system degradation. Including legumes in forage mixes may enhance soil-N presence and cycling, therefore mitigating the problem. To test this theory, signal grass [Brachiaria decumbens (Stapf) R. D. Webster] litter chemical composition and decomposition after inclusion of calopo (Calopogonium mucunoides Desv.) at 0, 50, or 100% of litter mass was evaluated. Litter samples were collected from both species and incubated by litter bag technique for 0, 4, 8, 16, 32, 64, 128, or 256 d in 2007 and 2008. Biomass decomposition was described by a simple exponential organic matter (OM) decay model (p < 0.0001; Y predicted [the remaining biomass at a given time of decomposition, predicted by the single exponential model] = 91.11 -0.00451t and 94.16 -0.00217t for year 1 and 2, respectively). Remaining biomass was lower (p < 0.05) in 2007 (28%) than 2008 (54%) following 256 d incubation at least in part because of greater lignin concentrations in 2008 litter. Pure signal grass litter C:N values were 74 to 76% greater (p < 0.05) than pure legume while the inclusion of 50% calopo reduced (p < 0.05) grass ratios by 62 to 64%. Net annual N mineralization increased (p < 0.05) from 27% without legume to 38% with legume inclusion at 50% of the grass litter, a nutrient cycling acceleration of 16% (p < 0.05). This research indicated that the inclusion of calopo will ameliorate N deficiency in soils of a signal grass pasture. Crop Science Society of America.

published proceedings


author list (cited authors)

  • Siqueira da Silva, H. M., Batista, D., Ferreira dos Santos, M. V., Lira, M., Lira, M., & Muir, J. P.

citation count

  • 21

complete list of authors

  • Siqueira da Silva, Hiran Marcelo||Batista Dubeux, José Carlos||Ferreira dos Santos, Mércia Virginia||de Andrade Lira, Mário||de Andrade Lira, Mário||Muir, James P

publication date

  • May 2012