Morphological characteristics and Classification of soils on slope position (toposequence) in the forest reserve of mining area, East Kutai Regency, East Kalimantan province, Indonesia

Agriculture Faculty, Mulawarman University, Samarinda, Indonesia

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Abstract

This study is aimed to obtain information about impact of different morphological characteristics of slope position (topo sequence) at Kutai Timur Regency. Three land system were choosen as study areas of Kutai Timur Regency of the three different fisography i.e undulating area, hilly area and steep area of the forest reserve. The descriptive research method used to identify the morphological characteristics of upper slope, middle and lower slope at three different fisiographic (topo sequence). The results show that the insitu weathering indicated by soil leaching cause of rain water infiltration and sedimentation lead to development of A horizon of silt loam and clay loam texture and a silt loam to clay loam in B horizon of the undulating terrain. The soil has A, B, C horizons and classified as Ultisols in upper, middle and lower but classified as Inceptisols of the valley area. The soil solum has variated depth I.e. between 83 - 186 cm (upper slope), 101 - 178 cm (middle slope) and 95 - 136 cm (lower slope). Soil on hilly terrain dominantly by Ultisols by length of slope between140 - 240 m and the elevation about 36 - 49 m asl. Soil solum about 96 - 168 cm (upper slope), 76 -173 cm (middle slope) and 73 - 181 cm on the lower by sandy clay loam to clay dominant texture on B horizon but with some coarse fragment especially in the middle slope. Steep terrain has 45 - 60% slopes by length slope about 500 m and the elevation around 59 - 133 m asl. The soil solum between 43 - 209 cm in the upper, 38 - 218 cm in the middle and 44 - 150 cm in the lower, and the most of soil has A - Bt -C horizon and classified as Ultisols.