Abstract
We investigated the effect of soil heating and rewetting on the characteristics of Ultisols from Pendopo, South Sumatra Province, Indonesia, in a laboratory experiment. Soil samples from the depth of 0-10 cm were subjected to different temperatures (100, 300, and 500°C) for different periods (4, 8, and 12 hr). The heated soils were then either rewetted or un-rewetted with deionized water. Heating significantly changed the color from dark brown to red, and significantly increased sand fraction and decreased clay fraction. The changes in soil fraction were observable during the first four hours of heating. Heating had drastic effect on soil mineralogy, even at lower temperature. Significant changes were also observed in soil chemical characteristics. Total C and N were almost totally eliminated at 500°C regardless of the heating time but increased with watering as compared with those did not receive water treatment. Soil pH also increased with heating up to 300°C in accordance with decreases in exchangeable Al and H of the soil. Watering further increased the pH, which was most likely due to decreases in soluble Al and H. Exchangeable bases and CEC significantly decreased with heating but increased again with watering. P also significantly decreased with increasing temperature. Heating time did not exert significant effect on available P, suggesting that the losses of P occurred mainly within the first 4 hr of heating. The results obtained partly explained immediate fertility degradation of heated soil unless proper management means are employed.
