Soil amelioration using steel slag in drained peatland under oil palm plantation increases CO2 emission

Increasing the productivity of tropical peatland can be achieved by soil ameliorations using steel slag and lateritic soil. However, the effect of such ameliorants on the peat decomposition is not well understood. This study was aimed to evaluate the influence of soil ameliorants of steel slag and lateritic soil to peat decomposition as reflected by CO2 emission. A year study was conducted in smallholder oil palm plantation in Jambi Province, Indonesia to monitor CO2 emission from treatments plots of control (T1), steel slag 600 kg ha−1 (T2), lateritic soil 600 kg ha−1 (T3) and a combination of T2 and T3 (T4), which each treatment had 5 replications. CO2 emission was measured every three months by a closed chamber method. Results showed that CO2 emission were followed the order of T4>T2>T1≥T3. CO2 emission from T4 (49 ± 20 t ha−1 year−1) was 20% higher than T1 (40 ± 23 t ha−1 year−1), while T2 (44 ± 17 t ha−1 year−1) was 9% higher than T1. CO2 emission from T3 (40 ± 14 t ha−1 year−1) was similar to T1. This study showed that steel slag accelerates peat organic matter decomposition which is indicated by higher CO2 emission of steel slag treatments compare to other treatments.