Soil Colour as an Indicator of Slash-And-Burn Fire Severity and Soil Fertility in Sumatra, Indonesia.

TitleSoil Colour as an Indicator of Slash-And-Burn Fire Severity and Soil Fertility in Sumatra, Indonesia.
Publication TypeJournal Article
Year of Publication2000
AuthorsKetterings Q, Bigham J
JournalSoil Science Society of America Journal
Start Page1826
Keywordsagriculutre, burning, Fire, forest, land use, shifting cultivation, Soil fertility, Sumatra
AbstractFire is widely used to convert forest to agricultural land in many developing countries, and correlations are thought to exist between fire severity, burned soil color, and soil fertility. To test this hypothesis, field experiments were conducted in Sepunggur, Jambi Province, Sumatra, Indonesia. Field burning a slashed 12- to 15-yr.-old secondary forest caused Munsell values and chromas to decrease and hues to become yellower with increasing heat severity, especially in the top 5 cm of the soil. However, at peak surface temperatures >600 °C, soil C was mostly depleted and the soil matrix was reddened. Laboratory studies showed similar results with static heating. Moreover, colour changes were highly dependent on the duration of exposure at a given temperature. Fire induced the formation of aggregates with exteriors that had lower values and chromas and slightly redder hues than the interiors. Laboratory removal of organic matter from burned samples by chemical oxidation did not alter the color. Soil exchangeable Ca, Mg, and K increased with fire severity, while exchangeable acidity and Al decreased 2 weeks after the burn. Soil C and N were reduced at high burn severity only. Phosphorus showed an increase in availability at low to medium fire severity and a decrease in availability at the most intense burn levels. Colours of burned areas in the field did not change significantly during the 12 weeks following the burn. However, within 12 weeks following the field burn exchangeable Ca had decreased to pre-burn levels and Al saturation had increased markedly. Using postburn colour measurements to predict the spatial patterns in soil fertility was limited by the fact that fertility changed rapidly following the burn, whereas color parameters did not.