Advances in agronomy volume 121

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Advances in agronomy volume 121

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ADVANCES IN AGRONOMY Advisory Board PAUL M BERTSCH RONALD L PHILLIPS University of Kentucky University of Minnesota KATE M SCOW LARRY P WILDING University of California, Davis Texas A&M University Emeritus Advisory Board Members JOHN S BOYER KENNETH J FREY University of Delaware Iowa State University EUGENE J KAMPRATH MARTIN ALEXANDER North Carolina State University Cornell University Prepared in cooperation with the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America Book and Multimedia Publishing Committee DAVID D BALTENSPERGER, CHAIR LISA K AL-AMOODI CRAIG A ROBERTS WARREN A DICK MARY C SAVIN HARI B KRISHNAN APRIL L ULERY SALLY D LOGSDON Academic Press is an imprint of Elsevier 525 B Street, Suite 1800, San Diego, CA 92101–4495, USA 225 Wyman Street, Waltham, MA 02451, USA 32 Jamestown Road, London, NW1 7BY, UK The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, UK Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands First edition 2013 Copyright © 2013 Elsevier Inc All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford,UK: phone: (+44) (0) 1865 843830; fax: (+44) (0) 1865 853333; email: permissions@elsevier.com Alternatively you can submit your request online by visiting the Elsevier web site at http://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made ISBN: 978-0-12-407685-3 ISSN: 0065-2113 For information on all Academic Press publications visit our website at store.elsevier.com Printed and bound in USA 13 14 15 16 10 CONTRIBUTORS Muhammad Afzal National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan Olafur Arnalds Faculty of Environmental Sciences, Agricultural University of Iceland, Hvanneyri, IS-311, Borgarnes, Iceland Guănter Brader AIT Austrian Institute of Technology GmbH, Bioresources Unit, Tulln, Austria Stephane Compant Dept Bioproce´de´s et Syste`mes Microbiens, Universite´ de Toulouse, LGC UMR 5503 (CNRS/INPT/UPS), ENSAT-INP de Toulouse, Castanet-Tolosan Cedex 1, France Jorge A Delgado USDA ARS Soil Plant Nutrient Research Unit, Fort Collins, Colorado, USA Ruth H Ellerbrock Leibniz-Centre for Agricultural Landscape Research (ZALF), Institute of Soil Landscape Research, Muăncheberg, Germany Horst H Gerke Leibniz-Centre for Agricultural Landscape Research (ZALF), Institute of Soil Landscape Research, Muăncheberg, Germany Carmen Hoeschen Lehrstuhl fuăr Bodenkunde, TU Muănchen, Freising, Germany Matt R Kilburn Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Australia Markus Kleber Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, USA Sumanta Kundu Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad, Andhra Pradesh, India Rattan Lal Carbon Management and Sequestration Center, The Ohio State University, Columbus, Ohio, USA Birgit Mitter AIT Austrian Institute of Technology GmbH, Bioresources Unit, Tulln, Austria Carlos M Monreal Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Center, Ottawa, Ontario, Canada ix x Contributors Carsten W Mueller Lehrstuhl fuăr Bodenkunde, TU Muănchen, Freising, Germany Muhammad Naveed AIT Austrian Institute of Technology GmbH, Bioresources Unit, Tulln, Austria Mark A Nearing USDA ARS Southwest Watershed Research Center, Tucson, Arizona, USA K.P Prabhakaran Nair Institute of Plant Nutrition, University of Hohenheim, Stuttgart, Federal Republic of Germany Jennifer Pett-Ridge Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California, USA Charles W Rice Kansas State University, Manhattan, Kansas, USA Morris Schnitzer Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Center, Ottawa, Ontario, Canada Angela Sessitsch AIT Austrian Institute of Technology GmbH, Bioresources Unit, Tulln, Austria A.K Singh Indian Council of Agricultural Research, Krishi Anusandhan Bhawan (KAB-II), New Delhi, India Ch Srinivasarao Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad, Andhra Pradesh, India Friederike Trognitz AIT Austrian Institute of Technology GmbH, Bioresources Unit, Tulln, Austria B Venkateswarlu Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad, Andhra Pradesh, India Peter K Weber Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California, USA PREFACE Volume 121 of Advances in Agronomy contains eight outstanding reviews dealing with technology advances, organic matter chemistry and composition, climate change, and crop and soil sustainability Chapter is an excellent and cutting-edge review on the use of NanoSims to study soil biogeochemical interfaces at fine scales Chapter details conservation practices to address climate change mitigation and adaptation Chapter is a comprehensive review of methodologies and techniques for analyzing soil organic matter over a range of spatial scales Chapter discusses the chemistry and biochemistry of organic components in rhizosphere soil solutions Chapter addresses ways to enhance agronomic productivity and carbon sequestration in soils of dryland ecosystems of India Chapter is a fine overview of constraints to crop production in the Middle East-West Asia region due to micronutrients Chapter covers beneficial interactions between plants, soils, and bacteria These advances are discussed in the context of improving the yield and health of food and feed crops Chapter provides a thorough discussion of the buffer power concept and the important role it plays in African and Asian soils, with relevance to soil testing and nutrient availability I am most grateful to the authors for their first-rate reviews DONALD L SPARKS Newark, Delaware xi CHAPTER ONE Advances in the Analysis of Biogeochemical Interfaces: NanoSIMS to Investigate Soil Microenvironments Carsten W Mueller*,1, Peter K Weber†, Matt R Kilburn‡, Carmen Hoeschen*, Markus Kleber}, Jennifer Pett-Ridge *Lehrstuhl fuăr Bodenkunde, TU Muănchen, Freising, Germany † Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California, USA ‡ Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Australia } Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, USA Corresponding author: e-mail address: carsten.mueller@wzw.tum.de Contents Introduction 1.1 The importance of nanoscale processes in soils research 1.2 Fundamentals of SIMS Experimental Approaches for the Study of Soil Microenvironments Using NanoSIMS 2.1 Lessons learned from geology and microbiology NanoSIMS Requirements for Soil-Related Studies 3.1 Technical considerations for soil samples 3.2 Sample documentation 3.3 Instrument tuning and quality control 3.4 Sample preparation—From single particles to intact soil 3.5 Data acquisition and analysis Combination with Other Microscale Techniques 4.1 Scanning and transmission electron microscopy 4.2 Synchrotron-based techniques 4.3 Atomic force microscopy 4.4 In situ single-cell labeling Conclusion Acknowledgments References Advances in Agronomy, Volume 121 ISSN 0065-2113 http://dx.doi.org/10.1016/B978-0-12-407685-3.00001-3 # 2013 Elsevier Inc All rights reserved 2 7 17 17 19 20 23 29 32 32 33 36 36 37 38 39 Carsten W Mueller et al Abstract Since a NanoSIMS high-resolution secondary ion mass spectrometry (SIMS) instrument was first used for cosmochemistry investigations over a decade ago, both interest in NanoSIMS and the number of instruments available have significantly increased However, SIMS comes with a set of challenges that are of both technical and conceptual nature, particularly for complex samples such as soils Here, we synthesize existing research and provide conceptual and technical guidance to those who wish to investigate soil processes at the submicron scale using SIMS, specifically with NanoSIMS Our review not only offers advice resulting from our own operational experience but also intends to promote synergistic research on yet unresolved methodological issues We identify and describe the basic setup of a NanoSIMS instrument, and important issues that may arise as a soil sample specimen are prepared for NanoSIMS analysis This is complemented by discussions of experimental design, data analysis, and data representation Next to experimental design, sample preparation is the most crucial prerequisite for successful NanoSIMS analyses We discuss the requirements and limitations for sample preparation over the size range from individual soil particles to intact soil structures such as macroaggregates or intact soil cores For robust interpretation of data obtained by NanoSIMS, parallel spatial, textural (scanning electron microscopy, atomic force microscopy), or compositional analyses (scanning transmission X-ray microscopy) are often necessary to provide necessary context We suggest that NanoSIMS analysis is most valuable when applied in concert with other analytical procedures and can provide powerful inference about small-scale processes that can be traced via isotopic labeling or elemental mapping INTRODUCTION 1.1 The importance of nanoscale processes in soils research Soil is often described as one of the most complex media on earth (Schulze and Freibauer, 2005) This complexity extends from the ecosystem scale to individual microaggregates, where nanometer-scale interactions between microbiota, organic matter (OM), and mineral particles are thought to control the long-term fate of soil carbon, nutrients, and pollutants (Lehmann et al., 2007; Schmidt et al., 2011) Processes that have a major impact at the landscape or global scale are determined by events occurring at the micro- and nanometer scales For example, entrapment of soil organic matter (SOM) within microaggregates with a diameter of less than 250 mm and SOM sorption onto even smaller clay and iron oxides is a vital mechanism for long-term preservation of organic carbon (OC) in soils (Lehmann et al., 2007; von Luătzow et al., 2006) Release of nutrients in the rhizosphere is NanoSIMS to Investigate Soil Microenvironments driven by root exudation at highly active micron-scale biogeochemical interfaces between roots, microbes, and minerals (Breland, and Bakken, 1991; Hinsinger et al., 2009; Norton and Firestone, 1996) Microbial activity occurs mostly in microhabitats (Dechesne et al., 2007; Muăller and Defago, 2006; Nunan et al., 2007) and involves mineralization of SOM and organic pollutants Hydrologic processes at the field scale are also influenced by finescale interactions as preferential flow paths may create localized zones of altered water and nutrient flow and thereby impact microbial abundance, community structure, and SOM turnover (Chabbi et al., 2009; Morales et al., 2010) Preferential flow zones are themselves heterogeneous at the microscale, with a heterogeneous supply of oxygen, water, and nutrients driving “hot spots” of microbial growth directly adjacent to areas of lesser microbial activity (Bundt et al., 2001) In all of these cases, activities at nano- to micron-scale soil biogeochemical interfaces determine the expression of higher level ecosystem functions The majority of soil research, however, is conducted on bulk (>1 g) samples, which are often significantly altered prior to analysis Pretreatments and analytical side effects include drying at varying temperatures, sieving/homogenization for process or elemental analysis, thermal alteration (as in pyrolysis GC/MS), or chemical alteration (as in alkaline extraction of “humic” substances or in cupric oxide oxidation for lignin analyses) With the advent of novel microspectroscopy and spectrometry techniques that allow for the study of micro- to nanoscale molecular, isotopic, and elemental patterns, it is now possible to make process-oriented observations (e.g., the stabilization of OM, sorption of pollutants, and mineral weathering) at the micron or submicron scale Elemental and isotopic imaging conducted via secondary ion mass spectrometry (SIMS) is a particularly promising technique for small-scale soil process research SIMS uses a high-energy ion beam to sputter material from a sample surface, which can then be analyzed in a mass spectrometer With high-resolution SIMS instruments (Cameca NanoSIMS 50, 50L, Gennevilliers, France), the distribution of elements and isotopes can be visualized with up to 50–150 nm lateral resolution within soil samples ranging from primary particles to subregions of intact soil cores For this reason, NanoSIMS has the potential to provide quantitative measures of OM–mineral–microbial interactions and biogeochemical processing at the macro- and microaggregate or single-cell scale Relatively, few SIMS experiments have been conducted to date in soil science In one of the first, Cliff et al (2002b) used time-of-flight SIMS (ToF-SIMS) and additions of 15N-labeled and 13C-labeled compounds to Carsten W Mueller et al study small-scale differences in N assimilation as a function of C versus N limitation When they compared SIMS values with bulk-measured microbial biomass N assimilation, they found substantial spatial heterogeneity in 15N distribution that was not apparent through bulk analysis (Cliff et al., 2007) More recently, studies using SIMS and NanoSIMS analysis have revealed effects at even finer scales within individual microaggregates, mineral surfaces, microbes, and root hairs (Blair et al., 2006; Cliff et al., 2002a; Clode et al., 2009; DeRito et al., 2005; Herrmann et al., 2007a,b; Keiluweit et al., 2012; Pumphrey et al., 2009) An early review paper by Herrmann et al (2007b) focused on potential applications for soil ecology and included the first application of the NanoSIMS technique with an intact soil microaggregate Subsequent publications have addressed the technical aspects (sample preparation) and investigations of organo-mineral associations at scales ranging from clay size mineral grain to intact soil cores (Keiluweit et al., 2012; Mueller et al., 2012b; Remusat et al., 2012) In this chapter, our goal is to provide insight into the range of potential NanoSIMS applications in soil system research, discussing technical capabilities and limitations, major sample requirements, and important complementary microspectrometry techniques As NanoSIMS applications in closely related fields, such as plant science and microbiology, have been reviewed recently (Moore et al., 2011a; Musat et al., 2012), we focus on the use of NanoSIMS in soil research 1.2 Fundamentals of SIMS SIMS is a surface analysis technique for solid samples Primary ions, with a kinetic energy ranging from a few hundred electron volts to tens of thousands of electron volts, are focused on the sample surface, ejecting atoms and molecules in a process called sputtering (see Fig 1.1) A small fraction of the ejected atoms and molecules is ionized and can be extracted with an electrostatic field into a mass spectrometer The fraction of the sputtered material that is ionized is determined by the ionization efficiency of the element in the sample matrix and is referred to as the secondary ion yield For different elements, secondary ion yields vary over many orders of magnitude and also strongly depend on the physicochemical nature of the sample (Storms et al., 1977; Wilson et al., 1989) Within the mass spectrometer, secondary ions can be separated according to their mass to charge ratio in a quadrupole, magnetic sector, or time-of-flight (TOF) mass analyzer These analyzers differ in terms of detectable mass range, sensitivity, ion transmission, and cost As NanoSIMS has both high sensitivity and spatial resolution NanoSIMS to Investigate Soil Microenvironments A B Analysis beam sources (Cs+,O-) Secondary ions to mass spectrometer – – – – – – Cs+ – – – – Primary beam – – – – – – – – – + – + e- – e- – e+ – – e+ e- Sample rs cto - e-e e- e- + n tio e et d c lle ico ult – M + ag 0.5 m Secondary beam M Sample mount (Si-wafer, TEM net, etc.) ne t Sample Figure 1.1 (A) coaxial setup of the NanoSIMS, indicating the primary and secondary ion beam in relation to the sample surface Due to the coaxial setup, the secondary ions must have the opposite charge from the primary ions to enable extraction to the mass spectrometer (B) Schematic of the NanoSIMS, with the primary ion beam in blue and the secondary ion beam in red Courtesy of Cameca (Gennevilliers, France), adapted from Myrold et al (2011) Reprinted from Myrold et al (2011), Copyright (2012), with permission from Elsevier at high mass resolving power, this particular SIMS instrument meets many of the specific requirements for microscale elemental and isotopic mapping analyses in soil science 1.2.1 NanoSIMS The NanoSIMS is optimized for SIMS imaging with submicron lateral resolution The NanoSIMS 50 and 50L instruments, conceived by Slodzian (Slodzian, 1987; Slodzian et al., 1992), were designed by Bernard Daigne, Franc¸ois Girard, and Franc¸ois Hillion (Hillion et al., 1993) and manufactured by Cameca France under a license from the Office National d’E´tudes et de Recherches Ae´rospatiales at Universite´ Paris-Sud (UPS ONERA) There are now more than 30 NanoSIMS instruments installed worldwide, working on a wide range of applications ranging from geology and cosmochemistry (Floss et al., 2006; Hoppe, 2006; Stadermann et al., 1999; Wacey et al., 2010a) to biology (Finzi-Hart et al., 2009; Kraft et al., 2006; Lechene ... PREFACE Volume 121 of Advances in Agronomy contains eight outstanding reviews dealing with technology advances, organic matter chemistry and composition, climate change, and crop and soil sustainability... embedding agent (Weber et al., 2012) The resin embedding approach has been used to prepare slices of intact soil cores for elemental mapping of in situ interfaces in a buried Oa horizon originating... 4.4 In situ single-cell labeling Conclusion Acknowledgments References Advances in Agronomy, Volume 121 ISSN 0065-2113 http://dx.doi.org/10.1016/B978-0-12-407685-3.00001-3 # 2013 Elsevier Inc

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  • Series Page

  • Copyright

  • Contributors

  • Preface

  • Advances in the Analysis of Biogeochemical Interfaces: NanoSIMS to Investigate Soil Microenvironments

    • Introduction

      • The importance of nanoscale processes in soils research

      • Fundamentals of SIMS

        • NanoSIMS

        • Basic requirements for NanoSIMS samples

    • Experimental Approaches for the Study of Soil Microenvironments Using NanoSIMS

      • Lessons learned from geology and microbiology

        • Investigating mineral?organic associations

        • Investigating intact three-dimensional microstructures

        • Investigating plant?soil processes

        • Tracking organic and inorganic pollutants

    • NanoSIMS Requirements for Soil-Related Studies

      • Technical considerations for soil samples

      • Sample documentation

      • Instrument tuning and quality control

      • Sample preparation?From single particles to intact soil

        • Direct deposition of individual particles and microaggregates

        • Fixation and preparation of organic materials

        • Preparation of aggregated soil structure and intact plant?soil systems

      • Data acquisition and analysis

    • Combination with Other Microscale Techniques

      • Scanning and transmission electron microscopy

      • Synchrotron-based techniques

      • Atomic force microscopy

      • In situ single-cell labeling

    • Conclusion

    • Acknowledgments

    • References

  • Conservation Practices for Climate Change Adaptation

    • Aggregate Impacts

    • Potential Effects of Climate Change on Soil Resources

      • Soil erosion: Drivers

        • Rainfall

        • Irrigation

        • Snow and winter processes

        • Wind

    • Climate Change and Soil Erosion

      • Changing rainfall erosion

      • Changing irrigation erosion

      • Changing snow-related erosion

      • Changing wind erosion

      • Changing agricultural production: Implications for soil erosion

    • Thresholds of Soil Erosion

    • Rates of Soil Erosion

      • Needed research

    • Soil Quality, Carbon, and Productivity

      • Mechanisms

      • Magnitudes of change

      • Thresholds

    • Soil Resources and Conservation Practices: Mitigation and Adaptation

      • Mechanisms to control and/or reduce inputs

        • Conservation agriculture: Tillage no-till/minimum tillage

        • Conservation agriculture: Crop residue, rotations, and cover crops

        • Precision agriculture and precision conservation

        • Buffers, riparian buffers, and wetlands

        • Agroforestry

        • Water quantity including irrigation

        • Opportunities to reduce methane emissions and capture energy

    • Can the Effects of Climate Change Be Ameliorated Using Practices?

    • Summary

    • References

  • Characterization of Organic Matter Composition of Soil and Flow Path Surfaces Based on Physicochemical Pri ...

    • Introduction

    • SOM Quantification as SOC

    • SOM Separation Methods

      • Density fractionation

      • Sequential extraction procedures

      • Sequential oxidation

      • Combination of density separation and sequential extraction

    • Methods for Determination of OM Composition

      • Physicochemical principles of the methods

      • NMR spectroscopy

      • IR/FTIR spectroscopy

        • Interpretation of FTIR spectra

        • A note on PCA/PLS analysis for determining soil Corg contents

    • Applying FTIR Spectroscopy in Organic Chemistry and in Soil Science

      • Spectral analysis of defined organic components and SOM

      • Applications of FTIR spectral analysis to characterize OM fractions

    • Relations Between SOM Composition and Soil Properties

      • CEC and SOM composition

      • Wettability of soils and SOM composition

    • From the Lab to the Field

      • Modifications by soil sampling of structured soils

      • Analyzing soil structural surfaces-Transect and map

    • Summary and Conclusions

    • Acknowledgments

    • References

  • The Chemistry and Biochemistry of Organic Components in the Soil Solutions of Wheat Rhizospheres

    • Introduction

    • Materials and Methods

      • Soil samples

      • Wheat growth

      • Collection of soil solutions

      • Four different growth stages of wheat

      • Pyrolysis-field ionization mass spectrometry

      • Semi-quantitative estimations

      • Analysis of sugars and polysaccharides

      • Analysis of amino acids

      • Identification of remaining m/z signals

    • Thermal Analysis of the Soil Solutions by Py-FIMS

    • Mass Spectrometric Analysis of the Four Soil Solutions at the Four Stages of Wheat Growth

      • Analysis of the chemical components in soil solutions by Py-FIMS

      • Carbohydrates in the soil solutions

        • Py-FIMS analysis of carbohydrates

        • Biochemistry and functions of carbohydrates in soil-plant systems

      • Free amino acids in soil solutions

        • Py-FIMS analysis of free amino acids

        • Biochemistry and function of amino acids in soil?plant systems

      • Phenols, lignin monomers, and lignin dimers in soil solutions

        • Py-FIMS analysis of phenols, lignin monomers, and lignin dimers

        • Biochemistry and functions of phenols, lignin monomers, and dimers in soil?plant systems

      • Alkylbenzenes in soil solutions

        • Py-FIMS analysis of alkylbenzenes

        • Biochemistry and functions of alkylbenzenes in soil?plant systems

      • Flavonoids in the soil solution

        • Py-FIMS analysis of flavonoids

        • Biochemistry and functions of flavonoids in soil?plant systems

      • Py-FIMS analysis of alkyl radicals

      • Saturated and unsaturated fatty acids and alkanes in the soil solutions

        • Py-FIMS analysis of fatty acids and n-alkanes

        • Biochemistry and functions of fatty acids and n-alkanes in the rhizosphere

      • N-containing components of soil solutions

        • Py-FIMS analysis of N-containing components

        • Biochemistry and functions of N-containing compounds in the rhizosphere

          • Biochemistry and functions of pyrroles in the rhizosphere

          • Biochemistry and functions of pyrazoles in the rhizosphere

          • Biochemistry and functions of pyrazines in the rhizosphere

          • Biochemistry and functions of pyridines and phenylpyridines in the rhizosphere

          • Biochemistry and functions of indoles in the rhizosphere

          • Biochemistry and functions of quinolines and their derivatives in the rhizosphere

          • Biochemistry and functions of carbazoles in the rhizosphere

          • Biochemistry and functions of other N-components in the rhizosphere

          • Future research on N-containing components in soil solutions

      • Steroids and sterols in the soil solution

        • Py-FIMS analysis of steroids and sterols

        • Biochemistry and functions of steroids and sterols in the rhizosphere

      • Esters of suberin in the soil solutions

        • Analysis by Py-FIMS of esters of suberin

        • Biochemistry and functions of suberin in rhizospheres

    • Summary of Component Classes and their IIs

    • The Role of Root Exudates in Soil Solutions

    • Similarities in Chemical Composition of Soil Solutions and Soil HSs

    • Proposed Mechanisms of HS Synthesis

    • Significance of the Organic Components Residing in Soil Solutions for Agri-Ecosystems

    • Conclusions

    • Acknowledgments

    • References

  • Sustainable Management of Soils of Dryland Ecosystems of India for Enhancing Agronomic Productivity and Seq ...

    • Introduction

    • Features of Dryland Ecosystems

      • Climate

      • Trends in key weather parameters

    • Soils of Drylands

    • Productivity of Dryland Crops

      • Long-term productivity trends

        • Groundnut

        • Finger millet

        • Finger millet-groundnut rotation

        • Rice-lentil

        • Winter sorghum

        • Soybean

        • Pearl millet

        • Other dryland crops

    • Productivity Constraints in Rainfed Ecosystem

      • Uncertain rainfall

      • Degraded soils

      • Low input application

      • Biotic stresses

      • Untapped water-nutrient synergy

      • Poor crop management

      • Lack of focused extension program

      • Lack of appropriate policy support

    • Strategies of Soil Quality Management

    • Nutrient Management

    • Carbon Stock of Dryland Soils and its Management

      • Soil carbon stocks in relation to production system

      • Carbon stocks in relation to rainfall

      • Carbon enhancing management options

        • Agricultural practices

        • Improvement of crop yield through Gliricidia green leaf manuring

      • Experiences from long-term experiments

        • Crop yield improvement through better nutrient management practices

      • Soil carbon stocks and agronomic productivity

        • Relationships of SYI to total cumulative C input

        • Relationships of SYI to SOC stock

        • Relationships of SYI to SOC sequestration

        • Carbon inputs in diverse rainfed production systems

        • Influence of root zone SOC stock on crop yield improvement

        • Profile SOC stock and SOC sequestration rate as influenced by nutrient management

        • Minimal carbon input requirements for arresting C depletion

      • Constraints to enhancing soil carbon stocks in drylands

      • Limitations of nutrients and water in enhancing soil carbon stocks

    • Biomass Input into Soils and Competing Uses of Crop Residues CRs

      • Availability of CRs

      • Competing uses of CRs

    • Improved Cropping Systems

      • Soil chemical properties

      • Conservation agriculture in rainfed agroecosystems

      • Pulse residue: A rich source of nutrients

      • Inclusion of legumes in the cropping systems: A strategy toward INM

    • Carbon Sequestration and Climate Change

    • Policy Interventions

    • Conclusions

    • Future Research Needs

    • References

  • The Influence of Volcanic Tephra Ash on Ecosystems

    • Volcanism: The Fire That Cools the Earth

      • Fire below

      • Distribution of volcanic activity

      • Approach

    • Volcanic Eruptions, Materials, and Dispersal Characteristics

      • Volcanic eruptions and tephra dispersal

      • Classification and terminology

        • Tephra and ash

        • Crystallinity

        • Chemical composition

        • Tephrochronology

    • Impact of Volcanic Eruptions

      • Lava flows, thick pyroclastic flows, and other major impacts

        • Lavas and pyroclastic flows

        • Lahars and jökulhlaups

      • Impact of tephra deposition

        • Responses of plants to burial: General considerations

        • Vegetation height

      • Ecosystem recovery after tephra deposition

        • Thick tephra deposits, 10cm

        • Moderately thick tephra deposits, 1-10cm

        • Thin tephra input, 1cm

        • Examples from Iceland

        • Interaction between tephra deposition and exotic/alien species

    • Secondary Impacts: Erosion

      • Hydrology and water erosion

        • Infiltration

        • Water erosion

      • Wind erosion and dust

    • Volcanic Ash and Soil Development

      • Andisols

      • Weathering of volcanic ash: Genesis

      • Carbon cycle considerations

      • Nutrient recharge by volcanic additions

    • Influence on Agriculture and Other Effects

      • Agriculture

      • Other effects

        • Streams

        • Insects

        • Animals

    • Conclusions

    • Acknowledgments

    • References

  • Advances in Elucidating Beneficial Interactions Between Plants, Soil, and Bacteria

    • Introduction

    • Microbial Habitats in Relation to Plant?Soil?Microbe Interactions

    • Ecology of Plant-Associated Bacterial Communities

      • Diversity of plant-associated bacterial communities

      • Interplay between soil, plant, and environment in shaping plant-associated microbial communities

        • The plant host structures plant-associated microbial communities

        • Effects of environmental parameters on plant-associated microbial communities

    • Beneficial Plant?Microbe Interactions

      • Plant growth promotion and nutrition

        • Biological nitrogen fixation

        • Production of plant hormones, vitamins, and bacterial volatiles

        • 1-Aminocyclopropane-1-carboxylate deaminase

        • Iron uptake and phosphate solubilization

        • Photosynthesis and polyamines

      • Biocontrol properties against plant pathogens

        • Outcompetition of pathogens

        • Disturbance of pathogen signaling

        • Direct antagonism against phytopathogens

        • Indirect mechanisms of biocontrol: Induction of systemic resistance responses in plants

      • Phytoremediation

        • Plant uptake of contaminants

        • Microbial processes in phytoremediation

    • Application Potential in Agriculture and Concluding Remarks

    • Acknowledgment

    • References

  • The Buffer Power Concept and Its Relevance in African and Asian Soils

    • Introduction

    • Efficient Plant Nutrient Management?The Key Factor in Sustainable Soil Management

      • Soil tests and nutrient ``availability´´

      • Rating soil tests to define nutrient availability and a fertility index

    • The Buffer Power and Effect on Nutrient Availability

      • Basic concepts

      • Measuring the nutrient buffer power and its importance in affecting nutrient concentrations on root surfaces

    • Quantifying the Buffer Power of Soils and Testing Its Effect on Nutrient Availability

      • Phosphorus

        • P buffer power measurement versus soil test P data for dependability of availability prediction

        • P buffer power and Q/I relationship

    • Case Studies from Asian Soils

      • Potassium

        • The importance of K buffer power determination in predicting K availability to perennial crops

        • The commercial significance of K buffer power determination in K fertilizer management for perennial crops

        • The role of the NH4+ on K+ availability

        • K buffer power measurement versus contemporary soil test K data for dependability of K availability prediction?The context of MYR and MEY approaches

        • K buffer power and Q/I relationship

    • The Role of EUF in Measuring P and K Intensity for the Construction of Buffer Power Curves

    • Quantifying the Buffer Power for Precise Availability Prediction?Heavy Metals

      • Zinc

      • Quantifying Zn buffer power

    • Case Studies with Asian Soils

      • South Asian soils

        • Quantifying the Z buffer power of the pepper-growing soils

      • Central Asian soils

    • Case Studies with African Soils

      • Other heavy metals

      • Molybdenum

      • Iron

      • Manganese

      • Boron

    • Influence of Heavy Metal Contamination on Buffering of Major Elements

    • Possible Buffering Effect on Plant Acquisition of Heavy Metals

    • Concluding Comments and Future Imperatives

    • Acknowledgments

    • References

  • Index

    • A

    • B

    • C

    • D

    • E

    • F

    • G

    • H

    • I

    • N

    • O

    • P

    • Q

    • R

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