Effects of peat fires on soil chemical and physical properties: a case study in South Sumatra

Peat fires have been an annual environmental crisis in Indonesia. In 2015, large parts of the country's peat were burned, impacting the health, education, and livelihoods of millions of Indonesians. Communities living on peat have practiced the burning of peatlands for a long time as they are convinced that this process will improve soil fertility. However, this assumption is not justified. This study examined the effect of a peat fire in 2019 in South Sumatra by comparing samples taken on an affected and unaffected smallholder oil palm plantation. These samples were analyzed to see the impact of fires on the peat soil. Results show that the ash content increased drastically by 57%. The fires improved the soil pH by 6%. However, the severe peat fires also caused negative impacts on soil fertility by reducing total nitrogen (6%), cation exchange capacity (8%) and soil organic carbon (2%). Furthermore, this study showed that peat fires decrease water retention capacity by 1 to 12 %. Contrary to popular belief among local farmers, this study shows the negative consequences of slash and burn activities on peat chemical and physical properties.