ASSESSING ECOLOGICAL SUSTAINABILITY OF SLASH-AND-BURN AGRICULTURE THROUGH SOIL FERTILITY INDICATORS

The objective of this study was to assess the near- and long-term impa ct of traditional slash-and-burn agriculture on soil fertility in the village of Kembera, West Kalimantan, Indonesia. Soil fertility is wide ly viewed as one of the key limits to sustainable production in slash- and-burn agroecosystems. A chronosequence of sites ranging from curren tly cultivated swiddens to a 28-yr fallow was surveyed. Organic C, cat ion exchange capacity (CEC), pH, nitrate, extractable basic cations, a vailable and total P, and extractable Al were measured as indicators o f soil fertility Inferred short-term trends point to significantly imp roved soil fertility conditions after burning in currently cropped swi ddens relative to falloffs. During the fallow, soil organic C, CEC, ni trate, total P, and extractable basic cations all manifest positive as sociations with fallow length after 3 to 11 yr of fallow; No declines in soil parameters were detected between plots based on the frequency of past slash-and-burn activity Therefore, there is no evidence that s lash-and-burn agriculture in Kembera has degraded these soil resources . While the results of this study suggest that slash-and-burn agricult ure in Kembera has been ecologically sustainable, recent changes in so cioeconomic factors influencing farmer's land-use decisions cast doubt upon the future sustainability of this agroecosystem.