The priming effect in compost amelioration of tropical peat soil

Abstract

Utilization of peat land for agriculture in Indonesia is increasing and some efforts in improving the peat soil fertility is being highly concerned. In addition to fertilizers, farmers add some fresher organic matter as the ameliorants, such as compost to support better microbial growth in the soil for increasing the decomposition process. Theoretically the addition of compost onto peat soil would lead to priming effect, hence it would accelerate the decomposition of peat organic matter. This study was to observe the impact of decomposition process due to adding compost to respiratory CO2 of peat soil. Peat soil from Central Kalimantan was used for experiment, incubated with KOH and then the respiratory CO2 was measured with titration method. Two different sizes of peat soil materials obtained from sieving peat soils, i.e. 5 mm and > the 5 mm. Each peat soil materials were mixed with 10%, 25%, and 50% compost to the total 100 grams. Post the compost addition, the samples were incubated for 20 days, and the respiratory CO2 was gauged for 4 times at 5 days interval during the incubation. It was showed that the more compost mixed to the peat soil materials, the more CO2 produced. The highest CO2 was 912.00 mg/g/day from compost incubation and a mixture of 50 gram of compost and coarse peat soil material produced 460.8 mg/g/day.