Tech. Tech. Bull. ISSN 0388-$394 Trop. Agr. Res. Center, Center, Japan No. 24 Technical Technical .. Bulletin of of the Tn:>picah Agriculture . Research Center .. No .. 24 1988 CHARACTERISTlCS ANlY GlNESIS OF V(JLCANICASI-I SOILS INTI-IE INTI-IE PHI llPPINES HIRQO OTSUKA, 1¥URELIO A .. BRIONES, NONILONA P. DAQUIADO, and FERNANDO A .. EVANGEUO TROPICAL・. TROPICAL・. AGRfCULTUR 正史 ESEARCH CENTER MlNlSTRY OF ACiRtCUtTUR えFORESτRY AND FISHERIES, JAPAN Tropical Agriculture Research Center Director General: Toshihiro KAJIW ARA Members of the Editorial Board Masanori MIYAKE, Chairman Masashi KOBAYASHI Tatsuzi TAKAHASHI Michio ARARAGI Iwao NISHIYAMA Kiyoto HASEGAWA Michio NOZAKI Editorial Secretary Takaaki ASAI Tropical Agriculture Research Center Ministry of Agriculture, Forestry and Fisheries Ohwashi, Tsukuba, Ibaraki 305, Japan Technical Bulletin of the Tropical Agriculture Research Center No. 24 CHARACTERISTICS AND GENESIS OF VOLCANIC ASH SOILS IN THE PHILIPPINES Hirao OTSUKA*, Aurelio A. BRIONESS**, Nonilona P. DAQUIADO**, and Fernando A. EVANGELIO** 1988 * Tropical Agriculture Research Center (TARC), Ministry of Agriculture, Forestry and Fisheries, Japan (Present address: National Institute of Agro­ Environmental Sciences, NIAES, 3-1-1 Kan-nondai, Tsukuba) ** Department of Soil Science, College of Agriculture, University of the Phili­ ppines, Los Banos, Laguna Tropical Agriculture Research Center Ministry of Agriculture, Forestry and Fisheries Ohwashi, Tsukuba, Ibaraki 305, Japan Printed by Foundation Norin Kosaikai CONTENTS Abstract . 1 Preface . 3 I. Introduction. 5 II. Distribution and morphological characteristics . 10 III. Some physical and chemical properties . 31 IV. Phosphate contents and distribution in Pedons . 62 V. Accumulation and properties of organic matter . 78 VI. Clay mineralogy, dissolution analysis, elementary composition of sand fraction, and soil classification . 93 References ................................................................ 119 l ABSTRACT OTSUKA, H., BRIONES, A.A., DAQUIADo, N. P., and EvANGELio, F.A. 1988 Characteristics and genesis of volcanic ash soils in the Philippines Tech. Bull., Trop. Agr. Res. Center, Japan, No.24 The Philippine islands are part of a circum-Pacific volcanic belt. There are many volcanoes and volcanic ash soils including 'Kuroboku-do', 'Andosols', 'Andepts' and 'Andisols', are widely distributed in this country. The objective of this study is to investigate the distribution of volcanic ash soils including their morphological characteristics, physico-chemical properties and charac­ teristics of organic matter in relation to clay mineralogy for the purpose of comparing these parameters with those of corresponding soils in Japan. Tagaytay soils are found on the northwestern slope of Taal volcano. Organic matter content decreases with decreasing elevation. They also show a high base saturation. The young volcanic ash and pumice have high total phosphorus contents. The buried humic layers and the A horizon were developed 1170 ± 70 yrs.B.P. and 710 ± 100 yrs.B.P., respectively. · Caliraya soil derived from Mt. Banahaw ejecta has a very low pH, high exchangeable aluminum content, low base saturation, low phosphate absorption and high peak of halloysite in the X-ray diffraction pattern. The soil may represent a transition from Andisols to Ultisols. Isarog soil showed the highest soil organic matter contents, high pH (NaF), high phosphate absorption and water contents but low exchangeable cation contents and bulk density. A similar behavior was observed for the Kuroboku soils with amorphous X-ray patterns in Japan. The age of the humic layers ranged from 580 ± 90 yrs.B.P. to 610 ± 90 yrs.B.P. Iriga soil in the Bicol area has a high pH, high exchangeable cation contents and base saturation. There were two types of soils from Mayon volcanic ash: one consisting of relatively old ash with a fine texture, high phosphate absorption and water content while the other consisted of young ash with a coarse texture and low phosphate absorption. Both of them display high exchangeable cation contents. Bulusan soil in Sorsogon has a low pH, high exchangeable aluminum content and low base saturation. Zambales soils derived from Mt. Pinutubo, Zambales province have a high pH, phos­ phate absorption, and coarse texture but low C.E.C. and water contents. Negros soils found at high elevations of Mt. Canlaon, Negros Occidental, have a high pH, high organic matter content and phosphate absorption but low exchangeable cation content with indications of the presence of amorphous clay minerals. 2 From the relationships established between the phosphate absorption coefficients and base saturation of the samples, volcanic ash soils in the Philippines and thosefromJapan may be classified into two groups according to varying combinations in the range of these two properties. Eighteen profiles were classified as Udoll, 2 profiles; Ochrept, 5 profiles, Andept, 9 profiles and Udult, one profile based on the Soil Taxonomy. Using ICOMAND, lOof them were classified as Udand and Ustand. It was considered that the volcanic ash soils in the Philippines have undergone a transition through two types: (1) Vitric Hapluudand + Pachic Hapluudand + Eutrochrept + Distrochrept + Haplu­ dult, and (2) Udivitrand, Vitric Hapludand, or Vitric Hapluustand + Pachic Hapludand + Hydric Melanudand. Index words: volcanic ash soil, age of humic layers, transition of andisal genesis, classifi­ cation characteristics, phosphate, humus, clay mineralogy. 3 PREFACE Total land area of the Philippines is about 30.00 million hectares. Agricultural land is subclassified into land area fully utilized (11.6 million hectares or 38.7% against the total area) and land area idle or under-utilized with a potential for agricultural development (3.13 million hectares or 10.4% against total area). The entire population of the country in 1985, was 56 million including a total labor force of 21.6 million. The aggregate agricultural labor force which is estimated at 10 million or 46.3% is composed of share tenants, agricultural lease holders, and regular and seasonal farm workers. Gross national product (GNP) contributed by the agricultural sector of the Philippines accounts for 1/4 of the total GNP and the agricultural exports account for about 40% of the total amount. However, there are many problems such as low agricultural productivity, depleted forests and low income, etc. in the agricultural sector. As described above, the agricultural sector is very important for the development of the social and economic conditions in the Philippines. Thus the new government of the Philippines is focusing its attention on the development of agriculture though long- and medium-term economic development programs with a comprehensive agrarian reform. To implement the programs, the soil resources for agricultural development must be surveyed and evaluated. It is also important to understand the characteristics, genesis, and classification of the Philippine soils in order to obtain basic information for soil utilization, soil management, and soil evaluation. The current studies dealt with volcanic ash soils, which are important for agriculture in the tropical area due to their fertility, during the senior author's stay at the Department of Soil Science, College of Agriculture, University of the Philippines, Los Banos (UPLB) for a period of 4 years. This report is the result of the cooperative research program between the Tropical Agriculture Research Center (TARC) and UPLB. 4 ACKNOWLEDGEMENT The authors would like to express their sincere thanks to Dr. Raul P. de Guzman, Chancellor, UPLB, Dr. Ruben L. Villareal, Dean, College of Agriculture, UPLB, Dr. Diosdard A. Carandang, Coordinator for Extension, Dr. Edilberto D. Reyes, Chairman, Department of Soil Science, Dr. Emil Q.Javier, former Chancellor, Dr. CledualdoB. Perez Jr., former Dean, and Dr. Santiago N. Tilo, former chairman for their assistance during these studies. The authors are most grateful for the advice and encouragement extended to them by Dr. Angelina M. Briones, Associate Professor, Dr. Edward Paningbatan, Assistant Pro­ fessor and other colleagues of the Department of Soil Science, and Dr. Tsuguo Adachi, Professor, Takai University. The authors would like to express their sincere gratitude to Drs. Sho-ichiro Nakagawa and Ken-ichi Hayashi, Former-Directors of the Tropical Agriculture Research Center, respectively, and Drs. Satoru Motomura, Shoshin Konno, Tatsuji Takahashi, Furnia Iwata, Masanori Miyake and Shohei Matsumoto, Deputy Directors of the Center, for their support and encouragement. Special thanks are also due to Dr. Toshihiro Kajiwara, Director General of the Tropical Agriculture Research Center, Dr. Yoshisuke Fujinuma, Director General of Chugoku Experiment Station, Dr. Akira Suzuki, Director of Soil Science and Fertilizer Depart­ ment, National Agriculture Research Center, and Dr. Koji Iimura, Director of Depart­ ment of Agriculture Chemistry of Hokkaido National Agricultural Experiment Station, for their suggestions. It is difficult to name all the persons who have collaborated with the authors in the implementation of those studies. However they would like to express their sincere appreciation to those people and herewith note that the studies might not have been implemented successfully without their cooperation. 5 I. INTRODUCTION I. 1. Agricultural Conditions Gross value added in agriculture (GNV), total production value, yield and harvest area in 1986 are shown in Table 1 according