ABSTRACT
Indonesia has 14.93 million hectares of peat land, with the largest part of it, around 6.44 million hectares are in Sumatra. Of the 6.44, about 3.85 million hectares are in Riau, particularly ombrogenous peat and topogenous which are influenced by salty and fresh water. In the management of the land, it is important to know the nature and characteristics of each peat soil. The purpose of this study was to determine the nature and characteristics of freshwater peat soils in parts of Riau Province. A total of 31 representative profiles derived from freshwater topogenous peat in Siak, Kampar, Rokan Hilir, Rokan Hulu and Dumai Regencies were examined. In addition, 73 soil samples were analyzed to determine their physical, chemical and fertility properties. From the analysis, freshwater topogenous peatland has a hemic maturity indicated by an average fiber content of about 71%, and a thickness varying from shallow (50-<100 cm) to very deep (> 500 cm) with fine-textured mineral (silty clay) soil substrates. Soil classified as Hemic Organoso has a low BD (0.05 to 0.33 g cm-3). However, peats in Kampar Regency have a relatively higher BD and ash content than other regions. The pH values range from 3.3 to 4.8. From the C/N ratio (15 to 69), indicating a requirement for nitrogenous fertilizer. Exchangeable cations (Ca, Mg, K, and Na) vary due to basic saturation (BS), though ranging from relatively low to very low. In addition, P2O5 levels (extracted 25% HCl) varied from very low to high (2 to 45 mg 100 g-1).
