Soil formation of new lahar materials derived from Mt. Pinatubo I. Physical and chemical properties of new lahar materials and soils formed by old lahar materials

• Published in: Soil science and plant nutrition (Tokyo) Vol. 49; no. 4; pp. 575 - 582
• Main Authors: Sasaki, Reina, Yoshida, Masao, Ohtsu, Yutaka, Miyahira, Miki, Ohta, Hiroyuki, Watanabe, Makiko, Suzuki, Sohzoh
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis Group 01.08.2003; Japanese Society of Soil Science and Plant Nutrition
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; lahar; Mt. Pinatubo; soil formation; soil weathering; soil formation; Soil science; soil weathering; lahar; Mt. Pinatubo
• ISSN: 0038-0768; 1747-0765
• DOI: 10.1080/00380768.2003.10410047

The early stage of weathering / soil formation processes from new volcanic mudflow (new lahar materials) brought from Mt. Pinatubo was examined. For this purpose, comparative studies on the physical / chemical characteristics of the new lahar materials and soils formed by the deposition of old lahar materials were conducted. Original soils contained less coarse sand, more silt, and clay than the new lahar materials. Increase in the clay content of the original soils reflected the progression of weathering. The occurrence of a higher leaching process of Fe, Ca, and Mg and of a moderate accumulation of organic matter in the original soils was suggested, based on the differences in the soil elemental composition and chemical properties. Values of base saturation and phosphate absorption coefficient (PAC) of the new lahar materials were 388% and 44, while those of all the original soils ranged 15-160% and 55-894, respectively. With the progression of weathering, the PAC value tended to increase gradually while the base saturation value decreased abruptly under the environmental conditions prevailing in the Philippines.