Non-natural firebreaks has been an alternative of wide use in forests, conservation units and at road borders to reduce fire propagation. The main objective of these firebreaks is to manage the fuel material, breaking the continuity of the fuel material. With the emergence of new products and equipment, the traditional firebreaks have being replaced by wet, green or chemical firebreaks. The objective of this work was to test the best dose of a fire retardant in a pasture area formed by Bracharia decumbens grass. Phos-chek retardant, a mixture of amonium phosphate and amonium sulphate, was used in the concentration of 0.134 kg/L. The doses were 300, 600, 900 and 1,200 ml/m². The application was carried out with a backpack pump in plots of 2 x 5 m, with four repetitions, using the complete randomized blocks design. The time spent by the fire to burn the plot without the product, time spent by the fire to burn the plot with the product, distance advanced by the fire within the plot with the product, and the burning intensity were measured. Relative moisture and wind speed were measured at one-hour intervals. The fire line took 25 times more to burn the plot with the product, in the plot with 1,200 ml/m², than the plot without the product. The fire burnt the entire plot with the 300 ml/m² dose, but the burning time in the plot with the product was larger than that one on the plot without the product. Phos-chek changes the combustion reaction, retarding the burning process and the greater the dose the greater the reaction of inhibition. The best dose was that of 1,200 ml/m², but further studies are necessary to final out the effects of doses from 900 to 1,200 ml/m², to improve the cost/benefit rate of product use.
Fire retardant; fire propagation reduction; chemical cut fire cleaning, and forest fire
