PSXI-29 Dynamics of litter decomposition in signalgrass and forage peanut mixed pastures. (7th December 2018)

• Record Type: Journal Article
• Authors: Menezes, R; Ribeiro, K; Dubeux, J; Anjos, A; Rezende, J; Pereira, O
• Is Part Of: Journal of animal science. Volume 96(2018)Supplement 3
• Page Start: 222
• Page End: 223
• Publication Date: 2018-12-07
• Subjects: nitrogen mineralization -- row spacing -- post-grazing height; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/sky404.484
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Introduction of legumes into tropical grass pastures can potentially produce changes in nutrient recycling. The objective of this study was to evaluate the dynamics of litter decomposition and nitrogen mineralization in signalgrass and forage peanut mixed pastures, using three row spacings (40, 50 and 60-cm) and two post-grazing sward heights (5 and 15-cm) + an additional treatment of signalgrass monoculture, in a 3 x 2 + 1 factorial scheme using a randomized block design with four replicates. The pre-grazing height of 25 cm was used and the canopy was lowered to the post-grazing heights through the "mob-grazing" by crossbred dairy cows. Litter samples (10 g) inside exclusion cages were placed in nylon bags (measuring 15 x 20 cm) and evaluated after 0, 4, 8, 16, 32, 64 and after 128 d of incubation on the soil surface. The data were grouped into grazing cycles and analyzed using the Proc Mixed procedure of SAS. After 32 days of incubation, litter biomass loss for the 40-cm plant row spacing (Y=93.855e -0.0050t ) was faster than others (50-cm=92.324e -0.0040t and 60-cm=92.304e -0.0038t ). The litter from mixed pastures showed higher decomposition rates after 28 days of incubation compared to signalgrass monoculture. This can be attributed to the higher N content and the lower C:N ratio, which resulted in a higher decomposition rate. In spite of the higher N content and lower C:N ratio in the litter from pastures with 5-cm post-grazing sward height, the treatments that allowed higher N mineralization rates and lower values of remaining N corresponded to the pastures with 15-cm post-grazing sward height. Higher litter decomposition rates were found for the 40-cm forage peanut plant row spacing and for the mixed pasture than signalgrass monoculture. Higher N mineralization rates were found for the 15-cm post-grazing sward height.