Carsten Marohn Rainforestation farming on Leyte island, Philippines – aspects of soil fertility and carbon sequestration potential Institute for Plant Production and Agroecology in the Tropics and Subtropics Faculty Agricultural Sciences, University of Hohenheim, 2007 Institute for Plant Production and Agroecology in the Tropics and Subtropics University of Hohenheim Prof. Dr. J. Sauerborn Rainforestation farming on Leyte island, Philippines – aspects of soil fertility and carbon sequestration potential Dissertation submitted in fulfilment of the requirements for the degree 'Doktor der Agrarwissenschaften' (Dr.sc.agr. / Ph.D. in Agricultural Sciences) to the Faculty Agricultural Sciences presented by Carsten Marohn Stuttgart 2007 This thesis was accepted as a doctoral dissertation in fulfilment of the requirements for the degree 'Doktor der Agrarwissenschaften' by the Faculty Agricultural Sciences at University of Hohenheim on 24/10/2007. Date of oral examination: 02/11/2007 Examination Committee: Supervisor and Review Prof. Dr. J. Sauerborn Institute for Plant Production and Agroecology in the Tropics and Subtropics, University of Hohenheim Co-Reviewer Prof. Dr. R. Jahn Institute for Agricultural and Nutritional Sciences, Martin Luther-University Halle-Wittenberg Additional Examiner Prof. Dr. J.N. Wünsche Institute for Special Crop Cultivation and Crop Physiology, University of Hohenheim Vice-Dean and Head of the Prof. Dr. W. Bessei Committee Dean of the Faculty Agricultural Sciences, University of Hohenheim • Contents 01 Introduction and scope.....................................................................................................6 1.1 Study area.....................................................................................................................7 1.1.1 Geography............................................................................................................7 1.1.2 Geology, geomorphology and soils......................................................................8 1.1.3 Climate...............................................................................................................13 1.1.4 Natural vegetation..............................................................................................17 1.1.5 Population, culture and economy......................................................................19 1.1.6 Land use, tenure and reforestation....................................................................22 1.2 Agroforestry systems...................................................................................................26 1.2.1 Rainforestation...................................................................................................27 1.3 Carbon sequestration..................................................................................................29 1.3.1 Climate change and carbon pools.....................................................................29 1.3.2 Institutional and legal framework for funding of carbon sequestration through afforestation and reforestation...........................................................................32 1.3.3 Potential of carbon sequestration through agroforestry....................................34 02 Sites, material and methods...........................................................................................36 2.1 Approach.....................................................................................................................36 2.2 Site selection for paired plots......................................................................................36 2.3 Land-use history and plot installation in Cienda.........................................................38 2.3.1 Species and planting material............................................................................38 2.3.2 Plot design..........................................................................................................43 2.4 Meteorological data.....................................................................................................44 2.4.1 Weather data......................................................................................................44 2.4.2 PAR measurements...........................................................................................44 2.5 Soil analyses...............................................................................................................45 2.5.1 Subplots and sampling scheme.........................................................................45 2.5.2 Soil profiles.........................................................................................................46 2.5.3 Soil sampling......................................................................................................46 2.5.4 pH.......................................................................................................................46 2.5.5 Bulk density and volumetric water contents.......................................................46 2.5.6 Gravimetric water contents and soil water potential..........................................46 2.5.7 Particle size distribution.....................................................................................47 2.5.8 Total nitrogen.....................................................................................................48 2.5.9 Phosphorus........................................................................................................48 2.5.10 CECeff, CECpot and base saturation..............................................................48 2.5.11 Exchangeable basic cations............................................................................49 2.5.12 Pedogenic oxides of Fe, Al and Mn.................................................................49 2.5.13 Soil organic carbon..........................................................................................49 2.5.14 Physical fractionation of soil organic matter....................................................52 2.5.15 Substrate-Induced Respiration........................................................................53 2.5.16 Basal respiration..............................................................................................54 2.5.17 Soil respiration..................................................................................................54 2.5.18 Phosphatase activity........................................................................................55 2.6 Biomass measurements..............................................................................................56 2.6.1 Mulched biomass...............................................................................................56 2.6.2 Undergrowth biomass and growth rates............................................................56 2.6.3 Root length and weight density..........................................................................56 2.6.4 Aboveground biomass growth of planted species.............................................56 • 3 • 2.6.5 C, N and P contents of plant tissues..................................................................58 2.6.6 Litter production..................................................................................................59 2.6.7 Litter decomposition...........................................................................................59 2.7 Plant measurements required for modelling...............................................................60 2.7.1 Crop parametrisation..........................................................................................60 2.7.2 Tree parametrisation..........................................................................................60 2.8 Statistics......................................................................................................................62 03 Characterisation of soils.................................................................................................63 3.1 Profile descriptions......................................................................................................63 3.1.1 Haplic Cambisol, Cienda PN1............................................................................64 3.1.2 Haplic Cambisol, Cienda PN2............................................................................66 3.1.3 Stagnic Luvisol, Cienda PN3..............................................................................68 3.1.4 Dystric Nitisol, Cienda (Rainforestation demo plot)...........................................70 3.1.5 Chromic Cambisol, LSU.....................................................................................72 3.1.5.1 Ferri-stagnic Luvisol, Marcos..........................................................................74 3.1.6 Ferri-chromic Luvisol, Pangasugan...................................................................76 3.1.7 Hypereutric Cambisol, stagnic properties, Maitum............................................78 3.1.8 Stagnic Cambisol, Patag....................................................................................80 3.1.8.1 Calcari-Mollic Leptosol, Punta........................................................................82 3.2 Synopsis and Discussion Soil Profiles........................................................................84 3.2.1 Parent Material...................................................................................................84