Setiawati, Astriana Rahmi
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Journal : Journal of Tropical Soils

Texture and Chemical Properties of Two Depth Soils in a Toposequence of Anak Krakatau Before December 2018 Eruption Setiawati, Astriana Rahmi; Lumbanraja, Jamalam; Nurul Aini, Septi; Dermiyati, Dermiyati; Buchari, Henrie; Naspendra, Zuldadan
JOURNAL OF TROPICAL SOILS Vol. 25 No. 2: May 2020
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2020.v25i2.71-81

Abstract

Anak Krakatau volcano is one of the famous volcanic mountains located in the sea to the south part of the Province of Lampung, Indonesia. The volcano was derived from the active Krakatau caldera that first appeared on the surface in 1930 or 47 years after the eruption of Krakatau in 1883. The materials produced by the Anak Krakatau eruption were very interesting related to soil forming materials, especially their physical and chemical properties. The objectives of this study were to present information about the texture and chemical properties of soil from Anak Krakatau Mountain taken at the southeast slope before the December 2018 eruption at two different depths. This study was conducted in March to September 2019 which consisted of two parts: (1) soil survey in the field and (2) soil analysis in the laboratory. Soil samples were taken from a toposequence at seven points with an interval about 15m above sea level (asl) on the southeast slope (approaching northeast) of the Anak Krakatau in July 2018 at the depth of 0-20 cm and 20-40 cm. The soil texture of Anak Krakatau mountain before eruption in December 2018 was sandy with the percentage of sand 98.82 - 99.59%; silt 0 - 0.59%; and clay 0.41 - 0.74%. The soil chemical properties of Anak Krakatau mountain were soil pH (H2O) 4.95 – 6.27; soil pH (KCl) 4.75 – 5.89; Cation Exchange Capacity 0.41 – 2.02 cmol(+) kg-1; Base Saturation 117.24 – 514.63%; CaO 2.63 – 6.34%; MgO 3.06 – 6.13%; K2O 0.019 – 0.034%; Na2O 0.035 – 0.080%; P-retention 82.10 – 84.74%; and organic carbon 0.06 – 0.72%. The SEM-EDX analysis showed that the amounts of Mg and Na were more than 1% and there were several trace elements present in Anak Krakatau soil, namely Sb (Stibium), Nb (Niobium), Y (Yttrium), F (Flour), Co (Cobalt), and Ba (Barium).
Changes of Soil Chemistry Characteristics of Tephra Mount Anak Krakatau-Indonesia, Through Leaching Experiment Setiawati, Astriana Rahmi; Lumbanraja, Jamalam; Kurnia, Ananda Ika; Hidayat, Manarul; Aini, Septi Nurul; Prasetyo, Dedy
JOURNAL OF TROPICAL SOILS Vol. 28 No. 2: May 2023
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2023.v28i2.57-70

Abstract

Studying the weathering process in pristine volcanic materials is crucial as this process will determine further soil characteristics. Mount Anak Krakatau is reported as one of the fastest-growing volcanoes. This volcano erupted powerfully in December 2018, ejecting tons of volcanic materials. These materials are considered pristine and unweathered tephra. Hence, a leaching experiment can be one of the crucial methods to predict further soil characteristics formed as climatic factors. Tephra sampling was conducted on 13 Augustus 2019 or eight months after the massive eruption of Mount Anak Krakatau in December 2018. Tephra samples were leached by deionized water (H2O), oxalic acid (H2C2O4) 0.02 M, and citric acid (C6H8O7) 0.02 M (solvents) for 90 days. pH of tephra increased approximately from  (3.95– 4.99 ) to (5.12–8.11). Organic-C rose about 0.2 to 1 point higher than organic-C of tephra before the leaching experiment. The increasing value of organic-C was predicted to increase CEC (Cation Exchange Capacity) (2.13–5.36 cmolc kg-1). After the leaching experiment, the tephra’s surface was weathered clearly as an impact of solvents and the growing of algae.