Comportamento do fogo em diferentes concentrações e tempos pós-aplicação de retardantes em área de eucalipto na transição Cerrado-Amazônia

The objective of this study was to evaluate the efficiency of fire retardants submitted to different concentrations and post-application times, in controlled burning of Eucalyptus urograndis fuel material (clone H13), in the transition of Cerrado-Amazon biomes from Mato Grosso state, Brazil. Two commercial retardants (Phos-Chek WD881® and Hold Fire®) and one alternative (hydrochloridating polymer - Nutrigel®) were evaluated in the syrup volume of 2.0 L m-2 at different concentrations (Phos-chek WD881: 0.1 Hold Fire: 0.7-0.9-1.1-1.3-1.5% Nutrigel: 0.0010-0.0025-0.0050- 0.0075-0.010%) and three post-application times on the combustible material (60, 90 and 120 minutes). The propagation velocity of the fire line, flame length and remaining and consumed combustible material were evaluated. The post-application time of 60 and 90 minutes of the retardants in the fuel does not affect the effectiveness of the products, however, after 120 minutes, there is a reduction in fire efficiency. Regardless of the time after application of the retardants, the optimal concentrations were 1.0; 1.5 and 0.006% for Phos-chek WD881, Hold Fire and Nutrigel for the 2.0 L m-2 spray volume.