BIOMASS PRODUCTION OF BRACHIARIA (Brachiaria brizantha) CV. MARANDÚ IN TWO SILVOPASTORAL SYSTEMS OF PINUS (Pinus elliottii) IN CORRIENTES, ARGENTINA

Abstract

Silvopastoral systems are important in northeastern Argentina (NEA), particularly in forests planted in the late 1990s and at the beginning of 2000. The aim of this study was to evaluate the effect produced by two thinning methods for Pinus elliottii Engelm. on the productivity of Brachiaria brizantha Stapf. cv. Marandú. The treatments under study were: T1: Selective thinning (392 trees ha-1) and T2: Systematic thinning (lines paired with alleys of 12 m, 348 trees ha-1). The aboveground biomass accumulation of the pasture was evaluated in both treatments. A stratified sampling was performed and three sectors were defined. Five cages of 1 m2 were installed in each sector, adding a total of 15 cages per treatment. The harvested material was weighed and placed in an oven, and then the dry matter content (kg MS ha-1) was determined. Photosynthetically active radiation (PAR), expressed in ?mol m-2 s-1, was determined in order to characterize the management systems based on the light that crosses the tree canopy. A repeated measures analysis was performed using mixed models through PROC MIXED of SAS. The comparison of means was performed with LSMEANS of SAS, using the Tukey-Kramer test at a confidence level of 95%. The average accumulation of biomass was higher in T2 compared to T1, reaching values of 898.3 kg MS ha-1 year-1 and 750 kg MS ha-1 year-1, respectively. Significant differences were found between the treatments (p < 0.0001).