Soils in the Bulia micro watershed of Gorontalo province, Indonesia, and their quality assessment

Ten representative pedons from the Bulia micro watershed of Gorontalo Province, Indonesia, were characterized and classified to determine its land quality (LQ) class. Angular blocky, sticky, plastic consistencies and a hard consistency prevailed in the soil structure. In the alluvial plains the soil texture is dominated by the clay fraction, while in the hills and volcanic mountains the sand fraction is dominated. The soils in the Bulia micro watershed also have acid to neutral reaction, with the range of very low to high OC (organic carbon) levels, the reserve of exchangeable bases was dominated by Ca2+ in two series patterns, namely: Ca2+ > Mg+ > Na+ > K+ and Ca2+ > Na+ > Mg+ > K+, cation exchange capacity (CEC) ranged from low to very high, and the base saturation varied from moderate to very high. The alluvial plain is represented by Inceptisol in P1 and Typic Humustepts (P7), also by Oxic Humustepts (P3), then Mollisol on P4 (Typic Argiudolls) and Typic Haplustolls (P6), Alfisol on P5 (Typic Paleustalfs). Entisol on P2 (Typic Ustipsamments) was found in volcanic mountains and P9 (Typic Paleustolls) P8 (Ultic Paleustalfs), P10 (Inceptic Haplustalfs) are typical of volcanic hills. On the alluvial plains the land was categorized as the LQ class II, III and IV, the volcanic mountains were the LQ class IV, while the land on the volcanic hills was categorized as the LQ class VI. River bank erosion on the land river terraces can be held by the manufacture of gabions, talud, cliff reinforcement plants and terraces. The soil temperatures and high clay content can be regulated by mulching and organic materials.