Distribution of organic carbon in Ultisol soils with citronella and pine vegetation, at Gayo Highlands, Aceh

Abstract

Soil organic matter is an indicator of soil fertility. The purpose of this study was to analyse various forms of soil organic carbon in citronella plantation, citronella plantation under pine tree, and soil under pine tree. Soil organic carbon in various forms was analysed from soil samples taken from each horizon and soil profile. The soil profiles observed were ultisol profiles planted with citronella, citronella under pine tree, and under pine tree, and slopes; 0-8%, 8-15%, 15 -25%, and 25-40%, in order to obtain 12 soil profiles with a total of 39 soil samples. Ultisols planted with citronella had higher soil organic carbon than ultisols planted with citronella under pine tree and ultisols under pine trees. Based on the slope, the highest soil organic carbon was obtained in the soil with a slope of 0-8%, and decreased with increasing slope. Based on soil depth, the highest soil organic carbon was obtained in the upper horizon, compared to the horizon below. The highest total soil organic carbon was obtained at the soil surface horizon with a slope of 0-8% and citronella was planted. This pattern of total soil organic carbon is similar to that of sesquioxide bound organic carbon, but is not consistent with that of free clay bound organic carbon.