Ulrich Schuler Towards Regionalisation of Soils in Northern Thailand and Consequences for Mapping Approaches and Upscaling Procedures Zur Regionalisierung der Böden von Nordthailand und ihre Auswirkung auf mögliche Kartieransätze und Upscaling Verfahren This thesis was accepted as a doctoral dissertation in fulfillment of the requirements for the degree “Doktor der Naturwissenschaften (Dr. rer. nat.)” by the Faculty of Natural Sciences at the University of Hohenheim on 15.09.2008. Date of examination: 15.09.2008 Examination Committee: Dean and Head of Committee: Prof. Dr. Heinz Breer Supervisor and Review: Prof. Dr. Karl Stahr Co Reviewer: Prof. Dr. Manfred Küppers Additional Examiner: Prof. Dr. Ulrich Haas Diese Arbeit wurde von der Deutschen Forschuungsgemeinschaft in Rahmen des Sonderforschungsbereiches 564 The Uplands Program: Nachhaltige Landwirtschaft und Landentwicklung in Bergregionen Südostasiens, Teilprojekt B1 gefördert. Contents I Contents 1 INTRODUCTION 1 1.1 PROBLEM STATEMENT 1 2 GENERAL DESCRIPTION OF THE REGION 3 2.1 PHYSIOGRAPHY 3 2.2 CLIMATE 4 2.3 GEOLOGY, PETROGRAPHY AND LANDSCAPE HISTORY 5 2.4 VEGETATION 7 2.5 ETHNIC GROUPS AND LAND USE SYSTEMS 8 2.6 SOILS 9 3 METHODS AND MATERIALS 13 3.1 THE MAPPED AREAS 13 3.1.1 Mae Sa Mai granite and gneiss area 13 3.1.2 Huay Bong sandstone area 16 3.1.3 Bor Krai limestone area 17 3.2 MAPPING 19 3.2.1 Reference soil map 21 3.2.2 Maximum Likelihood mapping 22 3.2.3 Grid based randomised mapping 25 3.2.4 Soil property mapping 26 3.2.5 Indigenous soil knowledge 26 3.2.6 Petrographic and geological mapping 27 3.2.7 Database 27 3.2.8 Data evaluation and processing 28 3.3 SOIL ANALYSIS 28 3.3.1 Soil physics 28 3.3.2 Soil and water chemistry 29 3.3.3 Mineralogy 31 4 RESULTS 33 4.1 PETROGRAPHY 33 4.1.1 Mae Sa Mai 33 4.1.2 Huay Bong 35 4.1.3 Bor Krai 36 4.2 SOILS AND SOIL PROPERTIES 40 4.2.1 Mae Sa Mai 48 4.2.2 Huay Bong 64 4.2.3 Bor Krai 76 4.3 LOCAL SOIL CLASSIFICATION 96 II Contents 4.3.1 Mae Sa Mai 96 4.3.2 Huay Bong 98 4.3.3 Bor Krai 100 4.4 RANDOMISED GRID CELL APPROACH 103 4.5 MAXIMUM LIKELIHOOD APPROACH 105 5 DISCUSSION 115 5.1 PETROGRAPHY 115 5.2 SOIL VARIABILITY 117 5.2.1 Variability of pH values 117 5.2.2 Variability of soil colour 118 5.2.3 Variability of A-horizon thickness 118 5.2.4 Variability of soil types 118 5.2.5 Variability of soil forming processes 120 5.2.6 The major soils of North-western Thailand 127 5.2.7 Soil forming factors and their consequences for predictive 132 mapping 5.2.8 Interdependency of soil forming factors 142 5.3 EVALUATION OF LOCAL SOIL KNOWLEDGE 145 5.4 MAPPING APPROACH EVALUATION 146 6 CONCLUSION AND OUTLOOK 153 6.1 GENERAL CONCLUSIONS 153 6.2 CONSEQUENCES FOR UPSCALING 153 6.3 COMPARISON OF MAPPING APPROACHES 155 7 SUMMARY 157 7.1 SUMMARY 157 7.2 ZUSAMMENFASSUNG 160 7.3 96#P3A L 164 8 REFERENCES 169 8.1 LITERATURE 169 8.2 OTHER INFORMATION SOURCES 180 9 APPENDIX 185 9.1 LIST OF FIGURES 185 9.2 LIST OF TABLES 188 9.3 DESCRIPTION OF REFERECE SOIL PROFILES 192 9.3.1 Profile 501* Humi-Ferralic Cambisol – Mae Sa Mai 192 9.3.2 Profile 502* Humi-Ferralic Cambisol – Mae Sa Mai 194 9.3.3 Profile 503* Humi-Ferralic Cambisol – Mae Sa Mai 196 9.3.4 Profile 504* Profondi-Humic Acrisol – Mae Sa Mai 198 Contents III 9.3.5 Profile 505* Profondi-Humic Acrisol – Mae Sa Mai 200 9.3.6 Profile 506* Humi-Ferralic Cambisol – Mae Sa Mai 202 9.3.7 Profile 507* Profondi-Humic Acrisol – Mae Sa Mai 204 9.3.8 Profile 508* Dystri-Humic Cambisol – Mae Sa Mai 206 9.3.9 Profile 509* Humi-Ferralic Cambisol – Mae Sa Mai 208 9.3.10 Profile 971 (1766) Cutani-Abruptic Luvisol – Huay Bong 210 9.3.11 Profile 973 (1767) Endoskeleti-Profondic Luvisol – Huay Bong 212 9.3.12 Profile 974 (1768) Humi-Stagnic Cambisol – Huay Bong 214 9.3.13 Profile 980 (1769) Dystri-Skeletic Regosol – Huay Bong 215 9.3.14 Profile 981 (1770) Dystri-Skeletic Regosol – Huay Bong 216 9.3.15 Profile 982 (1771) Dystri-Skeletic Regosol – Huay Bong 217 9.3.16 Profile 991 (1772) Ferri-Abruptic Luvisol – Huay Bong 218 9.3.17 Profile 1093 (1837) Dystri-Humic Cambisol – Huay Bong 220 9.3.18 Profile 1094 Skelti-Stagnic Cambisol – Huay Bong 222 9.3.19 Profile 1095 (1839) Dystri-Profondic Luvisol – Huay Bong 224 9.3.20 Profile 113 (1773) Calcari-Humic Gleysol – Bor Krai 226 9.3.21 Profile 449 (1774) Humi-Stagnic Fluvisol – Bor Krai 227 9.3.22 Profile 450 (1777) Humi-Anthric Umbrisol – Bor Krai 228 9.2.23 Profile 452 (1775) Dystri-Ferric Luvisol – Bor Krai 230 9.3.24 Profile 453 (1778) Ferri-Profondic Luvisol – Bor Krai 232 9.3.25 Profile 456 (1779) Dystri-Profondic Luvisol – Bor Krai 233 9.3.26 Profile 457 (1780) Profondi-Humic Acrisol – Bor Krai 234 9.3.27 Profile 479 (1762) Chromi-Eutric Cambisol – Bor Krai 235 9.3.28 Profile 1550 Umbri-Gibbsic Ferralsol – Bor Krai 236 9.3.29 Profile 1627 (1758) Glossi-Calcic Chernozem – Bor Krai 237 9.3.30 Profile 1629 (1759) Dystri-Profondic Luvisol – Bor Krai 238 9.3.31 Profile 1677 Profondi-Endostagnic Luvisol – Bor Krai 240 9.3.32 Profile 1678 Ferri-Stagnic Luvisol – Bor Krai 242 9.3.33 Profile 1679 (1757) Dystri-Profondic Luvisol – Bor Krai 244 9.4 Figures 246 9.5 Analytical data of reference profiles 250 IV Abbreviations Abbreviations 3+ -1 Al exchangeable aluminium [cmolc kg ] BD bulk density [g cm-3] BS base saturation [%] 2+ -1 Ca exchangeable calcium [cmolc kg ] -1 Ccarb carbon content of calcium carbonate [g kg ] -1 CECclay cation exchange capacity of the clay at pH 7 [cmolc kg ] -1 CECsoil cation exchange capacity of the soil at pH 7 [cmolc kg ] -1 Corg organic carbon [g kg ] -1 Ct total carbon [g kg ] ECEC effective cation exchange capacity of the soil at pH 7 -1 [cmolc kg ] Fed the Fe fraction, extractable in dithionite [%m] Feo the Fe fraction, extractable in oxalate [%m] + -1 K exchangeable potassium [cmolc kg ] -1 KCAL calcium-acetate-lactate extractable potassium [mg kg ] 2+ -1 Mg exchangeable magnesium [cmolc kg ] m asl meters above mean sea level M moles per litre ML maximum likelihood NA not analysed or investigated + -1 Na exchangeable sodium [cmolc kg ] NS not significant -1 Nt total nitrogen content [g kg ] -1 PCAL calcium-acetate-lactate extractable phosphorous [mg kg ] Sibumasu Siam, Burma, Malaysia, Sumatra SOTER World Soils and TERrain Digital Data Base (FAO 1995) WRB world reference base for soil resources Introduction 1 1. Introduction North-western Thailand exceeds many other tropical regions in variability of elevations, vegetation, climate, land use, and petrography. In the morphogenetic sense the landforms of Northern Thailand represent transitional features ranging from old continental blocks to the young alpine mountain chains (Kubiniok 1999). North-western Thailand is nowadays the homeland of many different ethnic minorities and refugees from neighbouring countries (Schliesinger 2000). Traditionally, the cultural background of these minorities dwelling in the mountainous highlands mostly classified them as hunters or shifting cultivators (Kunstadter et al. 1978). Due to dramatic population increases shifting cultivation has decreased rapidly (Ganjapapan 1998). Today, most of the people’s livelihoods depend on an increasingly intensified agriculture. The intensification of cultivation, the extension of deforestation and devastating fire during the dry season causes many severe problems not only to the high, but also to the lowlands. The highlands are facing soil erosion, nutrient leaching, decreases of other natural resources (e.g. drinking water, forest products) and yields (Panomtaranichagul and Nareuban 2005), finally resulting in a deterioration of farmers livelihoods (Ashadi 1992). The lowlands face increased sediment accumulations (Penny and Kealhofer 2005) as well as water pollution and flooding (Panomtaranichagul 2006). Solutions for these present problems comprise mainly the improvement of education to achieve an understanding of the environment and the shift from fully market oriented cultivation systems to site adapted cultivation systems, which are more sustainable and favour several crops to secure nutrition and stabilise income. The knowledge about the given soils, their properties, and distribution in the landscape is a prerequisite for the implementation of such site adapted and sustainable agricultural systems. 1.1 Problem statement and objectives Up to now, information on highland soils of Northern Thailand was quite sparse, though some studies of different comprehensiveness and foci were available. Hendricks (1981) investigated soil vegetation relations at three locations in Chiang Mai and Chiang Rai province. Hansen (1991) focused on soil formation and soil properties in a mountainous watershed in Chiang Mai province. Van Keer (1992) investigated the soils of seven different research sites within North-western Thailand. Weltner (1996) focused on soils, landform genesis and land suitability in the Doi Inthanon area. Kirsch (1998) studied the soil and relief genesis of soils in the Nam Mae Chan watershed. Anongrak (2003) investigated a soil catena in the Doi Inthanon area under consideration of vegetation and land use. 2 Introduction Reasons for the rather low data density are mainly terrain inaccessibility, steep slopes, remoteness from research centres and also political reasons like declaration of conservation areas and use by ethnic minorities.