Deposition and decomposition of litter in periods of grazing and rest of a tropical pasture under rotational grazing

Israel Oliveira Ramalho, Claudia de Paula Rezende, José Marques Pereira, Robert de Oliveira Macedo, Camila Almeida dos Santos, Rafael Cassador Monteiro, Bruno José Rodrigues Alves, Isabel das Neves Oiticica de Carvalho, Segundo Urquiaga, Robert Michael Boddey
2019 Ciência Rural  
ABSTRACT: The objectives of this study were to determine the rates of plant litter deposition and decomposition in Marandu pastures (Urochloa brizantha cv. Marandu) under a) three forms of nitrogen (N) supply, b) at different stages of rotational grazing and c) to compare the single-exponential decay constant ('k') derived from litterbags with values derived from estimates of deposited and existing litter (DEL technique). The three N supply treatments were: without or with N fertilization (zero
more » ... fertilization (zero or 150 kg N ha-1 yr-1) or with the legume Desmodium ovalifolium. There were no significant differences (p<0.05) between existing litter and rates of litter deposition and decomposition between the three N supply treatments. The litter decomposition rate was estimated using the DEL technique for the 7-day grazing periods and two subsequent 14-day periods in each 35-day grazing cycle. The litter decomposition rate was (P<0.05) higher for the second rest period (days 21 to 35) at 0.089 g g-1 day-1, than for the grazing period (0.038 g g-1 day-1) and for the first rest period (0.040 g g-1 day-1). The mean half-life of the litter was 12 days using the DEL technique while the estimate from the litterbags was 136 days. Results showed that estimates provided by litterbags severely underestimate the decomposition in relation to the DEL technique and predict a long-term accumulation of litter which is not observed.
doi:10.1590/0103-8478cr20190266 fatcat:a33up36sajcl5bbtjfnd2j7pvu