Litter Mass and Chemical Composition On Elephant Grass (Pennisetum purpureum Schum.) Pastures Under Different Stocking Rates and N Fertilization.

Litter dynamics play an important role on nutrient return in grazed pastures. Characterization of litter amount and its chemical composition is essential to determine nutrient flow through this pathway. Among other management practices, stocking rate and N fertilization exert influence on litter dynamics. The objective of this study was to evaluate the effect of three stocking rates (2.0, 3.9, and 5.8 AU / ha; 1 AU = 450 kg animal live weight) and three N levels (0, 150, and 300 kg N / ha / year) on litter mass and litter chemical composition, in Pennisetum purpureum Schum. cv. IRI-381 pastures, in 2009 and 2010. It was used a split-plot arrangement in a randomized block design, with the main plot formed by the stocking rate and the split-plot by the level of N fertilization. Interaction occurred (P < 0.05) between evaluation year and stocking rate for litter mass. In 2010, the highest stocking rates (3.9 and 5.8 AU / ha) resulted in lower litter mass (2461 and 2357 kg OM / ha) compared to 2009. Litter mass did not present a pattern along evaluation periods. Litter C:N ratio observed were above 30, suggesting N immobilization by microbial biomass. Litter N concentration did not differ among treatments, with average of 15.0 and 13.0 g N/kg for 2009 and 2010, respectively. Pasture management and rainfall affect litter mass on the ground and its C:N ratio. This has implications on litter decomposition and nutrient dynamics on pastures.