World Soils Book Series Series Editor Prof. Alfred E. Hartemink Department of Soil Science, FD Hole Soils Laboratory University of Wisconsin–Madison Madison USA For furthervolumes: http://www.springer.com/series/8915 Aims and Scope The World Soils Book Series brings together soil information and soil knowledge of a particularcountryinaconciseandreader-friendlyway.Thebooksincludesectionsonsoil research history, geomorphology, major soil types, soil maps, soil properties, soil classifi- cation, soil fertility, land use and vegetation, soil management, and soils and humans. Manuel Casanova Osvaldo Salazar • Oscar Seguel Walter Luzio • The Soils of Chile 123 Manuel Casanova Osvaldo Salazar Oscar Seguel Walter Luzio Department of SoilandEngineering Universityof Chile Santiago Chile ISSN 2211-1255 ISSN2211-1263 (electronic) ISBN 978-94-007-5948-0 ISBN 978-94-007-5949-7 (eBook) DOI 10.1007/978-94-007-5949-7 SpringerDordrechtHeidelbergNewYorkLondon LibraryofCongressControlNumber:2012954627 (cid:2)SpringerScience+BusinessMediaDordrecht2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting,reproduction onmicrofilmsorinanyotherphysicalway,andtransmissionorinformationstorageandretrieval,electronicadaptation, computersoftware,orbysimilarordissimilarmethodologynowknownorhereafterdeveloped.Exemptedfromthis legalreservationarebriefexcerptsinconnectionwithreviewsorscholarlyanalysisormaterialsuppliedspecificallyfor the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. 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Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface Imagine the narrowest and longest country in the world, where high snow-covered mountainscanbeseenfromtheoceanandhugeriverssculptthelandscape,wherefrequent volcanoeruptionscoverthelandwithash,whereearthquakesshaketheearthandtsunamis overwhelm the coastline, where enormous glaciers are retreating, and finally imagine a place where it never rains…. then you are seeing the majesty and magnificence of Chile. It should be noted that within Chilean territory you can find almost all the soil types observed in the world, but unfortunately these represent a scarce and fragile natural her- itage. Naturalresources are one of more important economic assets inChile, but to avoid over-exploitation of those considered nonrenewable, a transition toward sustainable development should be a priority. The vision of local soil scientists about the problems that afflict Chilean soils has been extendedtoabroaderconceptthanerosion,namelysoildegradation.Suchproblemswere unsuspected a few decades ago, but nowadays soils are studied in light of a wide range of complex and interconnected problems, which cast a long shadow over the future offertile Chilean land and await the light of wisdom. In response to increasing concerns about soil degradation and the sustainability of agricultural production potentials in almost all regions of Chile, many researchers and institutions have developed diverse and valuable initiatives. These efforts include resource inventories, the design and development of low-cost technological options, the develop- ment of ecologically sound cropping systems, and options designed to conserve and manage the agrobiodiversity and forest resources that exist in the country. However, because the use and management of soils depends on many different actors, only limited progress is possible unless all are involved in planning and implementing programs to conserve this vital natural resource. In this regard, involvement takes on a very wide connotation, from having a deep knowledge of soil dynamics to planning management within an ethical context of this true work of art by nature. v Acknowledgments A large number of people over a long period of time have greatly assisted in the devel- opment of soil science in Chile. A particular debt is owed to all those largely unknown stewards, the pioneer soil surveyors, who made it possible to understand the complex distribution of soils in Chile. We also thank all the soil scientists that have forged and are building daily soil knowledge in Chile, while apologizing to those who may have been inadvertently omitted in this book. Finally, the authors reserve special gratitude for the UniversityofChile,theircurrentworkplaceandalwaysreveredalmamater,whichallowed them to translate their passion for the Soils of Chile into this document. vii Contents 1 General Chile Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Territory Formation: Geology and Geomorphology . . . . . . . . . . . . . . . . . . . 1 1.2 Climate: From Desert to Glaciers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3 Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4 Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2 Main Features of Chilean Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.1 Soil Formation in Chile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2 Major Soil Zones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.2.1 Soils of the Hyper-Arid to Semi-Arid Zone . . . . . . . . . . . . . . . . . . . 27 2.2.2 Soils of the Mediterranean Zone. . . . . . . . . . . . . . . . . . . . . . . . . . . 56 2.2.3 Soils of the Rainy and Patagonian Zone . . . . . . . . . . . . . . . . . . . . . 71 2.2.4 Soils of the Insular (Easter–Juan Fernández) and Antarctic Zone . . . . 80 2.3 A Soil Map of Chile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 3 Management of Soil Properties in Chile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 3.1 Chemical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 3.1.1 Soil Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 3.1.2 Soil Salinity and Sodicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 3.1.3 Nutrient Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 3.2 Physical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 3.2.1 Bulk Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 3.2.2 Particle Size Distribution and Water Retention. . . . . . . . . . . . . . . . . 108 3.2.3 Structural Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 3.2.4 Pore Functionality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 3.3 Biological Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 3.3.1 Soil Organic Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 3.3.2 Soil Biodiversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 4 Human-Induced Soil Degradation in Chile . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.1 Erosive Soil Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.1.1 Water Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 4.1.2 Wind Erosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 4.2 Non Erosive Soil Degradation (Physical, Chemical and Biological). . . . . . . . 127 4.2.1 Soil Physical Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 4.2.2 Soil Chemical Degradation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 4.2.3 Soil Biological Degradation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 ix x Contents 4.3 Desertification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 4.3.1 Coquimbo Region and Patagonia, Two Emblematic Cases of Desertification in Extremes Zones of Chile. . . . . . . . . . . . . 145 4.3.2 Easter Island, an Example of Collapse by Soil Degradation. . . . . . . . 149 4.4 Future of Soil Conservation in Chile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Authors’ Biographies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 1 General Chile Overview Chile is a long (4,300 km) and narrow (180 km wide on geologicalhistory),itispossibletodistinguishfiveseparate average) country in the southwestern extreme of South main periods. The latest of these (Andean), occurring dur- America that presents varied and pristine landscapes truly ing late Early Jurassic to present, is characterised by con- unique in the world. Inhabited for around 10,000 year, its tinentalbreak-upandrepresentsthearchetypalexampleofa territory is bordered by Perú to the north through the subduction-related mountain belt. Concordia line, Argentina and Bolivia to the east through Belts of active volcanoes, the most significant tectonic the huge Andean altitude, the South Pole to the south and and geological events in the evolution of the Andes, have the Pacific Ocean along the western side. occurredsincetheLateOligocene,afterthebreak-upofthe Itscontinentallength,betweenthenorthernandsouthern Farallon plate into the Cocos and Nazca plates at approxi- boundaries, is approximately 4,200 km. Including the mately 27 ± 2 Ma. This resulted in a change from oblique Chilean Antarctic Territory, its longitude exceeds to more nearly orthogonal convergence between the Nazca 8,000 km.AregionoftheAntarcticcontinentisalsopartof and South American plates, as well as a greater than two- Chile,whichformsatriangleendingintheSouthPole.The foldincreaseinconvergencerates,whichtogetherproduced continental and insular territory amounts to 756,915 km2 a more than threefold increase in trench–normal conver- and the Antarctic territory to 1,250,000 km2 (Fig. 1.1). gence. This caused changes in subduction geometry which Chilean territory is very asymmetrical in its length and accelerated crustal shortening, thickening and uplift in the width, 4,300 km and approximately 180 km on average, Northern Central Andes, but resulted initially in extension respectively. The maximum insular width is 468 km and is and crustal thinning in the Southern Central and Southern locatedat52(cid:2)S.Themaximumcontinentalwidthisfoundin Andes. As a result of the increase in convergence rates, Antofagasta (Region II), between the Mejillones and the magmatic activity also increased along nearly all the Bolivian boundary (at 27(cid:2)S; 380 km) and the minimum Andean chain. continental width at 31(cid:2)37’S (90 km). As a nation, Chile The Late Cenozoic tectonics of the coast of Northern became independent in 1818 and today is administratively Chile reflects processes related to the seismic coupling divided into 15 Regions (Fig. 1.2), 50 Provinces and 341 between the subducted Nazca Plate and the overriding Municipal Governments. South American Plate. Although these processes probably occur in all eroding convergent margins around the globe, only in Northern Chile is the record preserved due to 1.1 Territory Formation: Geology the hyper-arid climate of the region (Allmendinger and and Geomorphology González 2010). The South American central volcanic zone (CVZ; Western South America is one of the best known conver- 18–27(cid:2)S) includes Chile and around 40 active volcanic gent margins on the Earth. The current cycle of ocean- centres(Fig. 1.3),aswellasaround20activeminorcentres continent convergence began in the Jurassic following the and/or fields and at least 6 potentially active fields. break-up of the Gondwana supercontinent and has been A zone where the passive Juan Fernández Ridge is continuing ever since with varying degrees of obliquity. In subducting the continental margin is present between the evolution of the Andean Orogen in Chile (c. 550 Ma approx.27and33(cid:2)S,correspondingtoaflat-slabsubduction M.Casanovaetal.,TheSoilsofChile,WorldSoilsBookSeries,DOI:10.1007/978-94-007-5949-7_1, 1 (cid:3)SpringerScience+BusinessMediaDordrecht2013