Changes in chemical and physical properties of hemic peat under fire-based shifting cultivation

Abstract

Fire is still the best tool for land preparation for shifting cultivation, because it is quick, cheap and easy. Unfortunately, it is not clear whether or not shifting cultivation is sustainable in terms of quality and duration. To elucidate this, research was conducted on shifting cultivation land in the village of Pelalawan, Pelalawan district, Riau Province, Indonesia. The research was conducted during dry season in the year 2001. The main objective was to determine changes in the soil's chemical and physical properties three and six months after burning. Results of research show that the fuel load in the site varied from 39.5-51.8 ton ha-1 and consisted of litter and branches, the fuel bed depth varied from 71.8 to 108.4 cm and the rate of fire spread varied from 1.1 to 2.5 m minute-1 and resulted in high flame temperatures that varied from 900 to 1100 °C. The high flame temperatures were accompanied by high fire intensities that varied from 2552.3 to 5050.9 kW m-1 caused peat destruction that ranged from 6.0 to 7.2 cm depth. At three months after burning there was only base saturation in hemic 2 increased significantly, while at six months there was only base saturation in both hemic 2 and 3. As for soil physical properties, it was found that only the water holding capacity increased at three and six months after burning.