Multi-Scale Biogeochemical Processes in Soil Ecosystems E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Serie: Wiley-IUPAC Series Biophysico-Chemical Processes in Environmental Systems
- Sprache: Englisch
MULTI-SCALE BIOGEOCHEMICAL PROCESSES IN SOIL ECOSYSTEMS Provides a state-of-the-art overview of research in soil biogeochemical processes and strategies for greenhouse gas mitigation under climate change Food security and soil health for the rapidly growing human population are threatened by increased temperature and drought, soil erosion and soil quality degradation, and other problems caused by human activities and a changing climate. Because greenhouse gas emission is the primary driver of climate change, a complete understanding of the cycles of carbon and major nutritional elements is critical for developing innovative strategies to sustain agricultural development and environmental conservation. Multi-Scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes is an up-to-date overview of recent research in soil biogeochemical processes and applications in ecosystem management. Organized into three parts, the text examines molecular-scale processes and critical reactions, presents ecosystem-scale studies of ecological hotspots, and discusses large-scale modeling and prediction of global biogeochemical cycles. Part of the Wiley - IUPAC Series on Biophysico-Chemical Processes in Environmental Systems, this authoritative volume: * Provides readers with a systematic and interdisciplinary approach to sustainable agricultural development and management of soil ecosystems in a changing climate * Features contributions from an international team of leading scientists * Examines topics such as soil organic matter stabilization, soil biogeochemistry modeling, and soil responses to environmental changes * Discusses strategies for mitigating greenhouse gas emission and improving soil health and ecosystems resilience * Includes an introduction to working across scales to project soil biogeochemical responses to climatic change Multi-Scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes is essential reading for scientists, engineers, agronomists, chemists, biologists, academic researchers, consultants, and other professionals whose work involves the nutrient cycle, ecosystem management, and climate change.
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Table of Contents
Cover
Series Page
Title Page
Critical Reactions and Resilience to Climate Changes
Copyright Page
SERIES PREFACE
PREFACE
LIST OF CONTRIBUTORS
1 INTRODUCTION
1.1. CONTEXT
1.2. SOIL RESPONSES TO ENVIRONMENTAL CONDITIONS AT DIVERSE SCALES: ORGANIC MATTER TRANSFORMATIONS AND FEEDBACKS TO CLIMATE
1.3. RECENT EMPIRICAL INVESTIGATIONS OF SOIL RESPONSES TO ENVIRONMENTAL CONDITIONS AT DIVERSE SCALES: MINERAL WEATHERING
1.4. CROSS‐SCALE DISCREPANCIES: TWO EXAMPLES OF NONLINEARITIES THAT CHALLENGE PREDICTIVE ABILITIES
1.5. MODELS AS A MEANS OF INTEGRATING ACROSS DISCIPLINES AND SCALES
1.6. CONCLUSIONS
ACKNOWLEDGMENTS
REFERENCES
SECTION 1: MOLECULAR‐SCALE PROCESSES AND CRITICAL REACTIONS
2 THE SCIENCE AND SEMANTICS OF “SOIL ORGANIC MATTER STABILIZATION”
2.1. THE CYCLING OF ORGANIC MATTER IN SOIL
2.2. WHAT IS “STABILITY?”
2.3. THE PARADIGM OF SORPTIVE PROTECTION/INTERACTIONS
2.4. THE PARADIGM OF ACCESSIBILITY: AGGREGATION
2.5. THE PARADIGM OF ACCESSIBILITY: HOW LOCATION MATTERS
2.6. MICROBIAL METABOLIC PERFORMANCE AS A FACTOR IN SOIL CARBON CYCLING
2.7. HABITAT PROPERTIES AS LOGISTICAL CONSTRAINTS
2.8. HABITAT PROPERTIES AND REACTANT SUPPLY
2.9. CONCLUSIONS
REFERENCES
3 INTERCONNECTING SOIL ORGANIC MATTER WITH NITROGEN AND PHOSPHORUS CYCLING
3.1. SOIL ORGANIC MATTER: THE KEY PLAYER FOR CONTROLLING NUTRIENT CYCLING
3.2. NITROGEN
3.3. PHOSPHORUS
3.4. CONCLUSIONS
REFERENCES
FURTHER READING
4 PLANT‐DERIVED MACROMOLECULES IN THE SOIL
4.1. INTRODUCTION
4.2. PLANT MACROMOLECULES AS INPUTS INTO THE SOIL
4.3. FRACTION‐SPECIFIC MOLECULAR ANALYSES
4.4. FATE OF PLANT‐DERIVED COMPOUNDS IN THE SOIL
4.5. ROOT‐ VERSUS SHOOT‐DERIVED CARBON IN THE SOIL
4.6. CONCLUSIONS
REFERENCES
5 MICROBE–BIOMOLECULE–MINERAL INTERFACIAL REACTIONS
5.1. INTRODUCTION
5.2. MICROBIAL COLONIZATION OF ROCK
5.3. MECHANISMS OF CELL ADHESION TO MINERAL SURFACES
5.4. MINERAL SURFACE REACTIONS OF EXTRACELLULAR BIOMOLECULES
5.5. HETEROAGGREGATE FORMATION
5.6. CONCLUSIONS AND FUTURE OUTLOOK
ACKNOWLEDGEMENTS
REFERENCES
SECTION 2: ECOSYSTEM‐SCALE STUDIES OF ECOLOGICAL HOTSPOTS
6 GREENHOUSE GAS EMISSIONS IN WETLAND RICE SYSTEMS
6.1. INTRODUCTION
6.2. CARBON BIOGEOCHEMISTRY
6.3. N CYCLES
6.4. FUTURE DIRECTIONS
REFERENCES
7 THE CHANGING BIOGEOCHEMICAL CYCLES OF TUNDRA
7.1. INTRODUCTION
7.2. THE CHANGING TUNDRA CARBON CYCLE
7.3. CHANGING TUNDRA NUTRIENT CYCLES
7.4. FUTURE PROJECTIONS
7.5. FUTURE RESEARCH DIRECTIONS
REFERENCES
8 LINKING SOURCES, TRANSFORMATION, AND LOSS OF PHOSPHORUS IN THE SOIL–WATER CONTINUUM IN A COASTAL ENVIRONMENT
8.1. PHOSPHORUS: AN ESSENTIAL NUTRIENT TURNED INTO A CONTAMINANT
8.2. TRANSFORMATION OF PHOSPHORUS IN SOILS
8.3. SURFACE AND SUBSURFACE FLOW OF PHOSPHORUS FROM AGRICULTURAL SOILS TO OPEN WATER
8.4. TRANSPORT OF PHOSPHORUS IN THE MAIN CHANNEL AND EXPORT TO OPEN WATERS
8.5. SOURCE TRACKING OF P RELEASED FROM SOILS AND UPLAND WATERSHED
8.6. IMPLICATION AND FUTURE RESEARCH DIRECTIONS
ACKNOWLEDGMENTS
REFERENCES
9 DEEP SOIL CARBON
9.1. INTRODUCTION
9.2. HOW MUCH CARBON IS STORED IN THE SUBSOIL?
9.3. HOW DOES CARBON ACCUMULATE AT DEPTH?
9.4. FACTORS CONTRIBUTING TO DEEP SOIL CARBON PERSISTENCE
9.5. VULNERABILITY OF DEEP SOIL CARBON
9.6. IMPROVING PREDICTIONS OF DEEP SOIL CARBON
9.7. CONCLUSIONS
ACKNOWLEDGMENTS
REFERENCES
SECTION 3: MODELING BIOGEOCHEMICAL CYCLES AND IMPROVEMENT OF ECOSYSTEM RESILIENCE
10 SOIL CARBON DYNAMICS AND RESPONSES TO ENVIRONMENTAL CHANGES
10.1. INTRODUCTION
10.2. SOIL C INVENTORY
10.3. SOIL C DYNAMICS
10.4. CLIMATE WARMING AND SOIL CARBON
10.5. PRECIPITATION CHANGE AND SOIL CARBON
10.6. NITROGEN DEPOSITION AND SOIL CARBON
10.7. Uncertainties in Modeling Soil C Dynamics
10.8. OUTLOOK: NEGLECTED FACTS AND FUTURE RESEARCH DIRECTIONS
10.9. CONCLUSIONS
REFERENCES
11 NEXT‐GENERATION SOIL BIOGEOCHEMISTRY MODEL REPRESENTATIONS
11.1. INTRODUCTION
11.2. PROPOSED SOM MODEL STRUCTURE
11.3. MATHEMATICAL INTEGRATION AND SOLUTION IN THE BeTR‐S MODEL FARM
11.4. BENCHMARKS
11.5. FUTURE WORK
11.6. CONCLUSIONS
ACKNOWLEDGMENTS
REFERENCES
12 BIOCHAR PRODUCTION AND AMENDMENT
12.1. INTRODUCTION
12.2. BIOCHAR PRODUCTION
12.3. BIOCHAR PROPERTIES OR CHARACTERIZATION
12.4. BIOCHAR AS A SOIL AMENDMENT
12.5. FUTURE RESEARCH
REFERENCES
13 COMPOST PRODUCTION, ANALYSIS AND APPLICATIONS IN AGRICULTURE
13.1. INTRODUCTION
13.2. THE COMPOSTING PROCESS
13.3. METHODS FOR ORGANIC MATTER ANALYSES IN COMPOST
13.4. LEGAL ASPECTS
13.5. AGRICULTURAL USES
13.6. CARBON SINK PROPERTIES
13.7. FINAL REMARKS
REFERENCES
14 BIOGEOCHEMISTRY IN DYNAMIC LANDSCAPES
14.1. INTRODUCTION
14.2. GEOCHEMICAL CONSTRAINTS ON THE EROSION‐INDUCED TERRESTRIAL CARBON SINK
14.3. MODELS FOR EROSION‐INDUCED CARBON SEQUESTRATION
14.4. DISCUSSION
14.5. CONCLUSION
ACKNOWLEDGMENTS
REFERENCES
INDEX
End User License Agreement
List of Tables
Chapter 2
TABLE 2.1.
Facets of “stability.”
TABLE 2.2.
Properties of stable and unstable Humus as identified by Waksman
...
TABLE 2.3.
Evolution of the paradigm of “chemical stabilization through hum
...
TABLE 2.4.
Major subdivisions of the soil system with unique opportunities
...
TABLE 2.5.
Oxygen requirements for the full conversion of a given substrate
...
Chapter 4
TABLE 4.1
Composition, sources, and degradation indicators of major solvent
...
TABLE 4.2
The δ13C values of bulk plant and soil organic matter and their m
...
Chapter 10
TABLE 10.1.
Possible mechanisms of N deposition on the storage and stability
...
Chapter 11
TABLE 11.1.
Representative equations for the processes and inter‐connection
...
TABLE A1.
Equations governing the change in each carbon pool over time in th
...
TABLE A2.
Variable definitions.
Chapter 12
TABLE 12.1.
Compositions of feedstocks which are commonly used for biochar
...
TABLE 12.2.
The solid yield, elemental compositions, and surface area (SA)
...
TABLE 12.3.
The solid yield and elemental compositions of hydrochars from d
...
TABLE 12.4.
Summary of studies assessing the impact of pyrochar on cation e
...
TABLE 12.5.
Summary of studies assessing the impact of hydrochar and pyroch
...
TABLE 12.6.
Summary of studies assessing the impact of pyrochar and hydroch
...
TABLE 12.7.
Summary of studies assessing the impact of pyrochar and hydroch
...
Chapter 13
TABLE 13.1.
Organic feedstock materials permitted for composting in Europe
...
TABLE 13.2.
Additives suitable for the optimization of the composting proce
...
TABLE 13.3.
Auxiliary agents used in composting.
TABLE 13.4.
Some typical physical and chemical feedstock properties to be h
...
TABLE 13.5.
Some definitions of composting and compost.
TABLE 13.6.
Types of compost and related physical and chemical characterist
...
TABLE 13.7.
Types of compost and related physical and chemical characteristi
...
TABLE 13.8.
Limits of impurities, pathogens, and inorganic and organic conta
...
TABLE 13.9.
Annual and cumulative loading rates of metals added by composts
...
TABLE 13.10.
Effect of 14 yr application of compost and mineral fertilizer o
...
TABLE 13.11.
Effect of compost application rate of 200 t ha−1 at planting o
...
List of Illustrations
Chapter 1
Figure 1.1. Time‐ and spatial‐scale over which many ecosystem functions are ...
Chapter 2
Figure 2.1. Positive feedback loop between CO
2
concentration in the atmosphe...
Figure 2.2. The top 10 processes recommended to be studied in the coming yea...
Figure 2.3. The “ability to resist” as a function of the mechanism acting on...
Figure 2.4. Contrasting views of lignin decomposition in plant litter. In th...
Figure 2.5. Model chemical structure for charcoal formed at a pyrolysis temp...
Figure 2.6. Carbon (
E
OC
) and Nitrogen (
E
N
) enrichment in the particle size f...
Figure 2.7. Turnover time of organic matter in density fractions increases a...
Figure 2.8. Evidence for increasing extent of microbial processing reflected...
Figure 2.9. (a) A microaggregate with a single bacterium (B) linked to the a...
Figure 2.10. Fabric of clay size fractions observed with transmission electr...
Figure 2.11. Retention of
14
C labeled and unlabelled C in soils incubated in...
Figure 2.12. Colonies of FISH‐stained bacteria in a sandy soil (same soil ty...
Figure 2.13. X‐ray μ‐CT image of pieces of organic matter (dark grey) and po...
Figure 2.14. (a) Pore system (resolution 120 μm) of an undisturbed Mollisol ...
Figure 2.15. (a) Approximate Nominal Oxidation States of Carbon (NOSC) for m...
Figure 2.16. (a) Variation in thermodynamic driving factor
F
T
for common ...
Figure 2.17. CUE as a function of the bioenergetic potential (NOSC) of subst...
Figure 2.18. Energy required to become oxidized (ΔG
Cox
energy requirement of...
Figure 2.19. The rhizosphere is a narrow zone of soil (a few millimeters wid...
Figure 2.20. Soil organic matter cycling as a matter of microbial metabolic ...
Chapter 3
Figure 3.1. A synopsis of nitrogen (N) cycling evolution along the global la...
Figure 3.2. A synopsis of phosphorus (P) cycling evolution along the global ...
Chapter 4
Figure 4.1. The structure of woody plant cell wall and its chemical composit...
Figure 4.2. The schematic structure of angiosperm lignin.
Figure 4.3. Polymer structures of cutin (a) and suberin (b).
Figure 4.4. Model structure of plant cuticular waxes.
Figure 4.5. Lignin monomers released by cupric oxide oxidation.
Figure 4.6. The structural diagram of chiral amino acids with
D
‐ and
L
‐enant...
Figure 4.7. Structures and classification of 20 common amino acids.
Figure 4.8. Major monomers of cutin (a) and suberin (b).
Figure 4.9. Solution‐state
1
H NMR spectra of alkaline extracts of vegetation...
Figure 4.10. Two‐dimensional
1
H‐
13
C NMR cross‐peaks of dissolved organic mat...
Figure 4.11. The distribution of major compound groups in dissolved organic ...
Figure 4.12. Model for plant litter decay phases and chemical changes.
Figure 4.13. Mechanisms of photo‐oxidation reactions.
Figure 4.14. The turnover time of bulk soil organic carbon (SOC) and specifi...
Chapter 5
Figure 5.1. Generalized schematic representation of the Gram‐positive and Gr...
Figure 5.2. Adhesion of eight strains of bacteria on 11 glass and metal‐oxid...
Figure 5.3. Classical DLVO predictions of interaction energy between S. onei...
Figure 5.4. Schematic representation of the total Gibbs energy of interactio...
Figure 5.5. Kinetic rate constants of four microbial strains on Ottawa sand ...
Figure 5.6. Bacterial adhesion correlated with total adhesion free energy as...
Figure 5.7. Typical setup of an ATR‐FTIR experiment in flow‐through mode sho...
Figure 5.8. Attenuated total reflectance Fourier transform infrared spectra ...
Figure 5.9. Diffuse reflectance infrared Fourier transform (DRIFT) spectra o...
Figure 5.10. Distribution coefficient for EPS from Bacillus subtilis followi...
Figure 5.11. Schematic of proposed influence of EPS on the formation of “com...
Chapter 6
Figure 6.1. Pathways for the decomposition of organic carbon under anaerobic...
Figure 6.2. Nitrogen transformation processes in soils that can lead to N
2
O ...
Chapter 7
Figure 7.1. (a) Thermokarst terrain on the north slope of Alaska (left) and ...
Figure 7.2. How the tundra carbon cycle is being affected by climate change....
Figure 7.3. The cumulative net ecosystem exchange (i.e. carbon balance) of t...
Figure 7.4. A sample nitrogen budget for an Arctic tundra ecosystem showing ...
Figure 7.5. How the Arctic tundra nitrogen cycle is being affected by climat...
Figure 7.6. Five earth system models predict the amount of change in soil (a...
Chapter 8
Figure 8.1. (i) Concentrations and isotope values of four P
i
pools in an agr...
Figure 8.2. Isotope values of three major P
i
pools in an agricultural soil a...
Figure 8.3. (a) Schematics of field‐to‐ditch transect showing position and s...
Figure 8.4. (a) Land use map of the East Creek watershed, (b) dissolved P
i
c...
Figure 8.5. Calculated mobilization (positive values) or retention (negative...
Figure 8.6. Phosphate oxygen isotope values of HNO
3
–P pool from three possib...
Figure 8.7. Inferred sources in the particulate matter in the creek using fi...
Figure 8.8. A conceptualized transverse cross‐section of a water body showin...
Chapter 9
Figure 9.1. Organic carbon is delivered to the subsoil through a variety of ...
Figure 9.2. Profile depth distribution of soil organic carbon (SOC) influenc...
Chapter 10
Figure 10.1. Global stock (a) and mass (b, per 5° latitude) of organic carbo...
Figure 10.2. Estimation of changes in the C budget of terrestrial ecosystems...
Figure 10.3. Schematic diagram of the two‐pool and three‐pool reduced comple...
Figure 10.4. The dual role of soil microbes as the agents of both soil C dec...
Chapter 11
Figure 11.1. Our proposed SOM modeling framework has representations of seve...
Figure 11.2. The seven soil biogeochemical network subunits (
S
1, S2, S3, S4,...
Figure 11.3. Observed and predicted soil C to 1 m depth at the 2° ELM grid c...
Chapter 12
Figure 12.1. Schematic process diagram for the factors affecting biochar pro...
Figure 12.2. Evolution of the number of publications on indexed journals con...
Figure 12.3. The product (solid [pyrochar or hydrochar], liquid [bio‐oil], a...
Figure 12.4. The typical dry (above) and wet (below) biomass feedstocks for ...
Figure 12.5. Structure of lignocellulosic biomass.
Figure 12.6. Change of mass yield of biochars with heating treatment tempera...
Figure 12.7. The average values of solid yield, elemental composition, and s...
Figure 12.8. Change of carbon (a), hydrogen (a), oxygen (a), H/C (b), and O/...
Figure 12.9. The organic carbon (OC) contents of pyrochars produced from dif...
Figure 12.10. The bi‐plot of O/C versus H/C of biochars from different feeds...
Figure 12.11. Changes in functional group chemistry of pyrochars from differ...
Figure 12.12. Changes trend of reaction degree and relative abundance of O‐a...
Figure 12.13. Comparison of the proportion of total signal intensity from CP...
Figure 12.14. Comparison of nuclear magnetic resonance (NMR) spectra of kero...
Figure 12.15. The specific surface area (SSA) by N
2
adsorption isotherm of p...
Chapter 13
Figure 13.1. Feedstock features affecting compost production and the quality...
Figure 13.2. Effect of the application of mineral N (130 kg N ha
−1
yea...
Figure 13.3. Effect of the application of mineral N (130 kg N ha
−1
yea...
Chapter 14
Figure 14.1. Pools of soil carbon in eroding and depositional landform posit...
Figure 14.2. Movement of topsoil from eroding position and delivery of most ...
Figure 14.3. Temporal dynamics of SOC storage in a hypothetical eroding catc...
Figure 14.4. Delineating the relative change in input and output fluxes of C...
Figure 14.5. Delineating the relative change in input and output fluxes of C...
Figure 14.6. Threshold conditions for soil erosion to constitute C sink. If ...
Guide
Cover Page
Series Page
Title Page
Copyright
SERIES PREFACE
PREFACE
LIST OF CONTRIBUTORS
Table of Contents
Begin Reading
Index
WILEY END USER LICENSE AGREEMENT
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Wiley‐IUPAC Series in Biophysico‐Chemical Processes
Series Editors: Nicola Senesi and Baoshan Xing
The Division of Chemistry and the Environment of the International Union of Pure and Applied Chemistry (IUPAC) is sponsoring this series which addresses the fundamentals of physical‐chemical‐biological interfacial interactions in the environment and the impacts on: (i) the transformation, transport, and fate of nutrients and pollutants, (ii) food chain contamination and food quality and safety, and (iii) ecosystem health, including human health. In contrast to classical books that focus largely on separate physical, chemical, and biological processes, this book series is unique in integrating the frontiers of knowledge of both fundamentals and impacts of interfacial interactions of these processes in the global environment.
Books in the series:
Biophysico‐Chemical Processes of Heavy Metals and Metalloids in Soil Environments, edited by Antonio Violante, Pan Ming Huang, and Geoffrey M. Gadd
Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems, edited by Nicola Senesi, Baoshan Xing, and Pan Ming Huang
Biophysico‐Chemical Processes of Anthropogenic Organic Compounds in Environmental Systems, edited by Baoshan Xing, Nicola Senesi, and Pan Ming Huang
Engineered Nanoparticles and the Environment – Biophysicochemical Processes and Toxicity, edited by Baoshan Xing, Chad D. Vecitis, and Nicola Senesi
Multi‐scale Biogeochemical Processes in Soil Ecosystems – Critical Reactions and Resilience to Climate Changes, edited by Yu Yang, Marco Keiluweit, Nicola Senesi, and Baoshan Xing
MULTI‐SCALE BIOGEOCHEMICAL PROCESSES IN SOIL ECOSYSTEMS
Critical Reactions and Resilience to Climate Changes
Edited by
YU YANGMARCO KEILUWEITNICOLA SENESIBAOSHAN XING
This edition first published 2022© 2022 John Wiley & Sons, Inc.
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Library of Congress Cataloging‐in‐Publication Data
Names: Yang, Yu, 1984‐ editor. | Keiluweit, Marco, editor. | Senesi, Nicola, editor. | Xing, Baoshan, editor.Title: Multi‐scale biogeochemical processes in soil ecosystems : critical reactions and resilience to climate changes / Yu Yang, Marco Keiluweit, Nicola Senesi, Baoshan Xing.Other titles: Wiley‐IUPAC series on biophysico‐chemical processes in environmental systems.Description: First edition. | Hoboken, NJ, USA : Wiley, 2022. | Series: Wiley‐IUPAC series on biophysico‐chemical processes in environmental systems | Includes bibliographical references and index.Identifiers: LCCN 2021023731 (print) | LCCN 2021023732 (ebook) | ISBN 9781119480341 (cloth) | ISBN 9781119480433 (adobe pdf) | ISBN 9781119480471 (epub)Subjects: LCSH: Soils–Environmental aspects. | Biogeochemical cycles. | Climatic changes. | Sustainable agriculture.Classification: LCC S596 .M86 2022 (print) | LCC S596 (ebook) | DDC 631.4–dc23LC record available at https://lccn.loc.gov/2021023731LC ebook record available at https://lccn.loc.gov/2021023732
Cover image: © Yingshi FengCover design by Wiley
SERIES PREFACE
This book is produced during the really dynamic and unsettling period of COVID‐19 pandemic, when the importance of science and technology has been recognized more than ever globally. Advancement of fundamental science plays an essential role in battling social, economic and public health crisis. What we have been experiencing and observing have urged us to continue our effort in understanding the complex natural ecosystem in all aspects.
Environmental science is truly integration of understanding about the physical, chemical, and biological processes in natural and engineering systems, crossing spatial and temporal scales. To address the up to date development in environmental science for tackling the complex systems, the Division of Chemistry and the Environment of the International Union of Pure and Applied Chemistry (IUPAC) has approved the creation of an IUPAC‐sponsored book series entitled Biophysico‐Chemical Processes in Environmental Systems to be published by John Wiley & Sons, Hoboken, NJ. This series addresses the fundamentals of physical–chemical–biological interfacial interactions in the environment and the impacts on: (i) the transformation, transport, and fate of nutrients and pollutants, (ii) food chain contamination and food quality and safety, and (iii) ecosystem health, including human health. In contrast to classical books that focus largely on separate physical, chemical, and biological processes, this book series is unique in integrating the frontiers of knowledge of both fundamentals and impacts of interfacial interactions of these processes in the global environment.
This book “Multi‐scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes” is Volume 5 of this Wiley‐IUPAC series. This book comprises 14 chapters by renowned experts, addressing the biogeochemical cycles of critical elements, i.e. carbon (C), nitrogen (N), and phosphorus (P). Differently from other books focusing on a single scale, this volume synthesizes the knowledge about C/N/P cycles from molecular to global scales. Integration and evaluation of research frontiers across a range of spatial scales provide researchers, practitioners, and policy makers with an overview of current understanding about the biogeochemical processes of these elements critical for soil health and food security in the face of global changes and challenges. Such upscaling efforts are immensely valuable for the development and recommendation of management strategies with the aim of mitigating climate change and increasing the resilience of soil ecosystems.
This book can be used by senior undergraduate and graduate students in environmental sciences and engineering, ecology, soil science, as well as agricultural and ecosystem sciences as an advanced reference book on the subject matter to integrate the latest development of understanding about soil biogeochemistry and agricultural ecosystem management. It can also serve as a useful resource book for professors, instructors, research scientists, professional consultants, policy makers, government regulators and other individuals who are interested in the biogeochemical processes of critical elements, crossing different spatial and temporal scales.
Nicola SenesiBaoshan XingSeries Editors
PREFACE
Biogeochemical processes in soil environments play an important role in regulating the emission of greenhouse gases (e.g. CO2, CH4, and N2O) and the availability of major nutritional elements (e.g. N and P). Systematic integration of knowledge about the soil biogeochemical processes is critical for sustainable agricultural development and mitigation of harmful effects derived from climate changes and requires research ranging from the atomic to global scale. Therefore, the overall goal of this book is to provide scientific and professional communities with the critical evaluation by internationally‐recognized and leading scientists on the biogeochemical processes of C/N/P cycling in soil ecosystems across multiple scales. Specific objectives of this book project are to address: (i) microscale characterizations of critical soil biogeochemical reactions of C/N/P; (ii) ecosystem‐level observations of soil biogeochemical processes; (iii) modeling of large‐scale cycles; and (iv) resilience of important processes to climate change and potential management strategy. By systematically evaluating recent progress in these areas, recommendations for future research priorities are provided. This book, Volume 5 of the Wiley‐IUPAC book series entitled “Multi‐scale Biogeochemical Processes in Soil Ecosystems: Critical Reactions and Resilience to Climate Changes”, will be an important reference for scientists, engineers, students, stakeholders and policy makers.
In total, there are 14 chapters in this book. It starts with an introduction chapter, authored by Drs. Billings and Sullivan, which highlights the challenge and opportunities for studying soil biogeochemistry across vast scales both spatially and temporally. Following chapters are organized in three parts. The part I focuses on “Molecular‐scale Processes and Critical Reactions”, with chapters dedicated to soil organic C stabilization, interactions of soil organic matter with the cycles of nitrogen and phosphorus, fate of plant‐derived organic matter in soils, and mineral‐microbe‐organic matter interactions. Zooming out to the scale of ecosystems, part II addresses “Ecosystem‐scale Studies of Ecological Hotspots”, with chapters on the cycles of C/N/P in agricultural rice field, tundra environment, deep soils, and coastal ecosystems. The last part is devoted to large‐scale modeling of nutrient cycles and climate mitigation strategies, covering biochar production, compost, and erosion management. Aiming to understand the driving force for the resilience of soil ecosystems and providing management guidance for stakeholders, this book provides the state‐of‐the‐art knowledge of the biogeochemical cycling of C/N/P, its resilience to climate change, and its implications for soil management.
We very much thank all chapter authors and reviewers who generously volunteered their time and effort, especially during the unprecedented and challenging period of the COVID‐19 pandemic. We also want to extend our gratitude to the staff of IUPAC and John Wiley & Sons, who provided strong support and assistance for publication of this book.
Sep, 2021Yu YangMarco KeiluweitNicola SenesiBaoshan Xing
LIST OF CONTRIBUTORS
Rose Z. Abramoff, Laboratoire des Sciences du Climat et de l’Environnement, Gif‐sur‐Yvette, France
Asmeret Asefaw Berhe, Department of Life and Environmental Sciences, School of Natural Sciences, University of California, Merced, CA, USA
Sharon A. Billings, Department of Ecology and Evolutionary Biology and Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, KS, USA
Roland Bol, Institute of Bio‐ and Geosciences, Agrosphere (IBG‐3), Forschungszentrum Jülich, Wilhelm‐Johnen‐Str., 52425 Jülich, Germany
Nicholas J. Bouskill, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Luisella Celi, Soil Biogeochemistry, Department of Agricultural, Forest and Food Sciences, University of Torino, Grugliasco, Italy
Massimo Centemero, CIC, Italian Compost Consortium, Rome, Italy; and ECN, European Compost Network, Bochum, Germany
Jon Chorover, Department of Environmental Science, University of Arizona, Tucson, AZ, USA
Claudio Ciavatta, Alma Mater Studiorum University of Bologna, Bologna, Italy
Jinzhi Ding, Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
Xiaojuan Feng, Institute of Botany, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
Bo Gao, State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China
Teamrat A. Ghezzehei, Department of Life and Environmental Sciences, School of Natural Sciences, University of California, Merced, CA, USA
Lanfang Han, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou, China
Eleanor U. Hobley, Department of Soil Science, Technical University of Munich, Freising, Bavaria, Germany
Caitlin E. Hicks Pries, Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
William R. Horwath, Department of Land, Air and Water Resources, University of California, Merced, CA, USA
Deb P. Jaisi, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA
Sunendra R. Joshi, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA; and Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
Markus Kleber, Department of Crop and Soil Science, Oregon State University, Corvallis, OR, USA
Friedrike Lang, Institute of Forest Science, Department of Soil Ecology, University of Freiburg, Freiburg, Germany
Adam Lindsley, Department of Crop and Soil Science, Oregon State University, Corvallis, OR, USA
Lingli Liu, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, China
Jörg Luster, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
Erika Marín‐Spiotta, Department of Geography, University of Wisconsin – Madison, Madison, WI, USA
Arash Massudieh, Department of Civil Engineering, Catholic University of America, Washington DC, USA
Joshua M. McGrath, Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
Jennie R. McLaren, Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, USA
Kristi A. Mingus, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA; and USDA‐Natural Resources Conservation Service, Price, UT, USA
Shuli Niu, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
Shilong Piao, Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China; and Sino‐French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China
William J. Riley, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Daniel Said‐Pullicino, Soil Biogeochemistry, Department of Agricultural, Forest and Food Sciences, University ofTorino, Grugliasco, Italy
Nicola Senesi, University of Bari Aldo Moro, Bari, Italy
Carlos A. Sierra, Max Planck Institute for Biogeochemistry, Jena, Germany
Pamela L. Sullivan, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
Ke Sun, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, China
Mingjing Sun, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA; and Department of Physical Sciences, Emporia State University, Emporia, KS, USA
Jinyun Tang, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
Moreno Toselli, Alma Mater Studiorum University of Bologna, Bologna, Italy
Claire Treat, Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
Kiran Upreti, Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA; and Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA
Lydia Smith Vaughn, Department of Integrative Biology, University of California, Berkeley, CA, USA
Carolina Voigt, Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland; and Department of Geography, University of Montréal, Montréal, Canada
Tao Wang, Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
Baoshan Xing, Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, USA
Rongzhong Ye, Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC, USA
Claudio Zaccone, University of Verona, Verona, Italy
Qing Zhu, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
1INTRODUCTION: WORKING ACROSS SCALES TO PROJECT SOIL BIOGEOCHEMICAL RESPONSES TO CLIMATE
Sharon A. Billings1 and Pamela L. Sullivan2
1 Department of Ecology and Evolutionary Biology and Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, KS, USA
2 College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
1.1. Context
1.2. Soil Responses to Environmental Conditions at Diverse Scales: Organic Matter Transformations and Feedbacks to Climate
1.2.1. Organic Matter at the Microscale
1.2.2. Organic Matter at the Mesocosm Scale
1.2.3. Organic Matter at the Plot and Decadal Scale
1.2.4. Organic Matter at Ecosystem to Landscape Scales Across Years to Decades
1.3. Recent Empirical Investigations of Soil Responses to Environmental Conditions at Diverse Scales: Mineral Weathering
1.3.1. Mineral Weathering at the Column or Mesocosm Scale
1.3.2. Mineral Weathering at the Ecosystem to Landscape Scale Across Diverse Temporal Scales
1.4. Cross-Scale Discrepancies: Two Examples of Nonlinearities That Challenge Predictive Abilities
1.5. Models as a Means of Integrating Across Disciplines and Scales
1.6. Conclusions
Acknowledgments
References
1.1. CONTEXT
The physical, chemical, and biological features of soil are a time‐integrated reflection of the interactions between life and rock, as mediated by environmental conditions. Soil thus has been the object of study by multiple disparate disciplines for centuries (Jenny 1980; Hillel 1982; Callaham and Hendrix 1997; Brantley et al. 2007; Richter and Yaalon 2012; Billings et al. 2018). Historically, there have been some attempts to appreciate soils in a more holistic, interdisciplinary manner (e.g., Richter and Billings 2015), but recently a critical mass of scientists has recognized the importance of working across disciplines to address fundamental questions about soil functioning (Brantley et al. 2017; Rasmussen et al. 2011; Billings et al. 2012; Ziegler et al. 2017; Baatz et al. 2018; Richter et al. 2018). Indeed, many scientists now agree that to move forward in our predictive understanding of how soils will respond to climate change, we need to integrate across historically separate disciplines.
Working across disciplines is inherently challenging (see discussion in Richter et al. 2018), but addressing questions about soil responses to global climate forcings introduces yet additional difficulties: it requires working across wide‐ranging spatial and temporal scales. For example, soil organic C (SOC) losses to CO2 and mineral dissolution are driven by small‐scale microbial and chemical processes, respectively, but they also are governed by processes such as organo‐mineral stabilization of SOC (Lawrence et al. 2015) and weathering patterns (Riebe et al. 2004), which are often measured across long timescales (i.e., centuries to millennia). Accurate predictions of future fluxes of SOC and mineral nutrients are critical for projecting global‐scale atmospheric CO2 concentrations in the coming century (Wieder et al. 2013; Koven et al. 2013; Manzoni et al. 2017), but understanding the drivers of both fluxes requires that we understand mechanisms at small spatial and temporal scales (i.e. nanometers and seconds, respectively; Burghelea et al. 2015; Lehmeier et al. 2016) and integrate these processes with each other across fine to coarser scales. The environmental science community has devised multiple ways of meeting these challenges. Empirical studies at the microcosm, plot, catchment, and whole ecosystem scale have been critical for developing our burgeoning understanding of soil responses to climate change. In addition, the modeling community has developed invaluable tools for investigating soil responses to climate change. Such models offer a means of scaling measurements of short‐term system responses to forcings across longer timescales, generating estimates of system responses at large spatial scales, and for testing large‐scale and long‐term hypotheses.
In this introductory chapter, we highlight several empirical and modeling advances that serve as examples for studies that move us closer to a predictive understanding of soil functioning with anthropogenic climate change. We focus on exemplar studies that reveal mechanisms driving known phenomena, highlight observations consistent or inconsistent with theory, provide puzzling clues about linearities and nonlinearities in soil processes, or demonstrate the power of modeling for synthesizing any of these empirical works. We attempt to demonstrate how studies conducted at diverse spatial and temporal scales can reveal both congruencies and discrepancies across those scales, spotlighting where additional work is needed. We also formulate suggestions for integrating empirical and modeling studies to project future soil functioning. Underscored in this synthesis is the need to understand how mechanisms elucidated at one spatial or temporal scale function across diverse scales, such that we can formulate accurate projections of ecosystem function in the future.
1.2. SOIL RESPONSES TO ENVIRONMENTAL CONDITIONS AT DIVERSE SCALES: ORGANIC MATTER TRANSFORMATIONS AND FEEDBACKS TO CLIMATE
1.2.1. Organic Matter at the Microscale
Organic matter transformations in soils are studied across diverse scales (Figure 1.1). A long history of studies of reaction kinetics – perhaps the smallest scale appropriate for soil specialists – provides fundamental knowledge of both organic matter and mineral transformations (Pilling and Seakins 2005). More recent studies have focused especially on environmental variables expected to change with anthropogenic climate change (e.g., Wallenstein et al. 2009; Craine et al. 2010). For example, organic matter decay and associated patterns of nutrient and C release, when examined in isolation from the soil matrix and even microbes themselves, reflect fundamental reaction kinetics (Billings et al. 2015). Such studies indicate that temperature: (i) affects behaviors of individual exo‐enzymes differently (Lehmeier et al. 2013), (ii) is dependent on solution pH (Min et al. 2014), and (iii) drive age‐related declines in catalytic rates differently for individual exo‐enzymes (Billings et al. 2016). As a direct result of these complex and interacting effects, the relative abundances of microbially available resources (e.g., glucose, and N‐rich N‐acetyl‐glucosamine) change with temperature, pH, and exo‐enzyme age. However, the direct responses of exo‐enzymes and microbes to temperature do not necessarily scale up linearly, as discussed below (Section 1.2.3). This knowledge prompts interesting questions about potential long‐term, larger spatial responses of microbes to the changing landscape of resource availability, feedbacks to organic matter transformations, and ultimately to microbially driven CO2 release from soils and plant nutrient availability.
Research that incorporates microbial populations into studies of organic matter transformations moves one step closer toward mimicking complex environmental systems. Such studies permit control of relevant factors except the environmental condition of interest, while incorporating biotic responses. For example, Pseudomonas fluorescens, a ubiquitous soil bacterium, increases its respiratory demand for C as temperature increases and increases its respiratory 13C discrimination as well (Lehmeier et al. 2016), a phenomenon that necessarily leaves behind an isotopic fingerprint on microbial necromass. Discrimination against 13C also can occur during substrate uptake, an effect that varies with temperature and C availability (Min et al. 2016), suggesting that δ13C signatures of extant soil organic matter reflect countless discriminatory events during microbial substrate selection. Because microbial necromass likely serves as an important component of relatively persistent soil organic matter (Kallenbach et al. 2015; Schweigert et al. 2015; Liang et al. 2016), these findings suggest that microbial 13C discrimination during soil C transformations have a meaningful influence on SOC isotopic signatures. It remains unknown how any changes over time in microbial community composition with environmental conditions may modify 13C flows; certainly, we must take this into consideration if microbial populations exhibit different flows of 12C and 13C. However, because δ13C signatures of SOC serve as important constraints on soil C dynamics (e.g. Blagodatskaya et al. 2011; Breeker et al. 2015; Kohl et al. 2015), temperature influences on microbial 13C discrimination likely are important factors to consider when interpreting SOC δ13C signatures.
1.2.2. Organic Matter at the Mesocosm Scale
Myriad studies populate the literature that describe soil organic matter transformations as they respond to environmental conditions in controlled, mesocosm conditions. The most influential studies working at the mesocosm scale are those that seek to understand fundamental mechanisms governing ecosystem‐scale observations or phenomena, or those that manipulate soil mesocosms from many, diverse locations in an attempt to understand if often‐observed patterns are ubiquitous. For example, recent work demonstrates that the ratio of fungal to bacterial biomass is positively associated with SOC storage (Malik et al. 2016), a finding with meaningful implications given that the relative dominance of fungi and bacteria in soils can depend on substrate type, and thus on environmental conditions (e.g., Ziegler and Billings 2011). Diverse soil mesocosms incubated at varied temperatures imply that slowly mineralized soil organic compounds exhibit greater temperature sensitivity (Craine et al. 2010), consistent with theory and hinting at a fundamental feature governing soil‐atmosphere feedbacks. Mesocosm‐scale experiments have further demonstrated that inferences regarding the temperature sensitivity of SOC mineralization to CO2 depend on whether soil horizons are incubated individually or together (Podrebarac et al. 2016), a vital comment on the importance of designing mesocosm studies such that inferences are most applicable. Mesocosms have also provided insight into the seasonality of evapotranspiration under different climate change scenarios, demonstrating that the soil moisture dynamics so critical for organic matter transformations, and groundwater recharge, depend on both growing season and winter conditions (Pangle et al. 2014).
Figure 1.1. Time‐ and spatial‐scale over which many ecosystem functions are typically considered. Parameters listed represent a sample study demonstrating a cross‐scale approach for projecting future soil functioning as part of the National Science Foundation’s Established Program to Stimulate Competitive Research (EPSCoR) project in the state of Kansas, USA. From top to bottom, solid gray boxes indicate those processes or features assessed over continental or landscape scales, the watershed or plot scale, and the meso‐ or microcosm (or cellular) scale, respectively. Unboxed, double‐headed arrows within the panel represent erosion, hydrologic flow, and mineral weathering rates quantified at diverse scales. Red‐shaded arrow and associated red* text designate nascent realizations of increasingly short timescales over which soil structure and hydrologic flow paths may change. This project strives to link microbiome structure and process rates, hydrologic flow regimes, soil structure, land‐use history, contemporary rooting depth distributions, and soil gases across the precipitation gradient in central North America. Experimental manipulation of pedon‐scale mesocosms is one facet of the project that permits investigators to assess the influence of currently contrasting and altered precipitation regimes on soil structure and associated ecosystem parameters. To project soil system functions like release of gases and solutes to the atmosphere and surrounding aquatic systems, we must rely on models to move across spatial and temporal scales. From the forests in the east to shortgrass prairies in the west, these diverse scales can be examined in an integrative manner via reactive transport models elucidating how hydrologic flows govern patterns of mineral weathering and solute release, and through structural equation models that illuminate dominant casual pathways driving ecosystem properties and fluxes. See text for discussion of these model types.
Source: Based on Janzen (2004).
1.2.3. Organic Matter at the Plot and Decadal Scale
Plot‐scale work has an important advantage over micro‐ and meso‐scale work because it incorporates plant inputs and more natural climate forcings. With those advantages come the cost to the investigator of working with a less controlled environment, but recent work demonstrates how plot‐scale work provides avenues of exploring cascading, net effects of climate change in soil profiles, particularly over yearly and decadal timescales. For example, Melillo et al. (2017) demonstrate how ~25 years of soil warming can result in reductions in microbial biomass and concurrent loss of extant SOC stocks in both organic and mineral soil horizons, and enhanced rates of microbially mediated lignin transformations in mineral soil horizons. That study also demonstrates the challenges of upscaling short‐term, positive responses of microbial CO2 release to warming to longer timescales: after multiple years, these positive responses to increasing temperature were not maintained (Melillo et al. 2017). After 12 years of plot‐scale warming, shortgrass steppe soils also demonstrated greater C losses and a shift toward enhanced degradation of complex C substrates (Feng et al. 2017). Though not conducted on decadal timescales, whole soil pit warming has demonstrated similar temperature sensitivities at 70 cm depth as in surface soils, across plots (Hicks Pries et al. 2017). Plot‐scale manipulations in precipitation regime have provided clues to future soil profile responses to climate change as well: in response to drought, soil bacterial composition exhibited a greater degree of compositional resilience relative to fungi, which exhibited greater legacy effects of their native moisture regime (Martiny et al. 2017). The mechanisms driving these organic matter responses to warming and moisture variation are not clear, nor are they linear, but we can formulate some hypotheses based on work at smaller scales. For example, we might hypothesize that long‐term reductions in microbial biomass with soil warming at the plot‐ and decadal‐scale (Melillo et al. 2017) result from enhanced microbial demand for respiratory C and subsequent lower allocation of C to growth, which has been observed in controlled studies of an isolated bacterial population (Lehmeier et al. 2016). We also might hypothesize that observed drought responses of soil bacteria and fungi reflect these groups’ distinct strategies for coping with osmotic vs. drought stress (e.g., Boot et al. 2013). The development and testing of hypotheses such as these represent examples of important steps forward in linking small‐to‐larger scale phenomena that can ultimately enhance our predictive understanding of ecosystem functions.
1.2.4. Organic Matter at Ecosystem to Landscape Scales Across Years to Decades
Latitudinal gradients offer more specific insight into the influence of temperature regime on soil functioning, though many such gradients confer changes in ecosystem type as well as temperature regime (e.g., Sjogersten et al. 2003). A research platform in eastern Canada, the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect, offers similar dominant vegetation in all catchments in spite of a >5 °C difference in mean annual temperature across its latitudinal span. This transect provides a relatively rare opportunity to investigate the potential influence of the extent of climate change projected for the coming century, before any wholescale biome shift from mesic boreal forests to cool temperate forests. Though vascular plant and moss inputs vary somewhat across the transect (Kohl et al. 2017), soil C chemistry at these sites can be used to infer how climate regime may influence soil C stocks in the coming century without the confounding influence of different biomes’ leaf litter inputs to the profiles. Multiple geochemical indices suggest that soil organic matter is relatively more degraded by soil microbes at warmer sites (Li et al. 2012; Laganière et al. 2015; Philben et al. 2016), in spite of radiocarbon signatures of SOC at warmer sites suggesting that soil C stocks there experience more rapid turnover (Ziegler et al. 2017). Quantified fluxes of C throughout these forests indicate that increasing MAT results in enhanced rates of forest C cycling but that greater soil CO2 and dissolved organic C (DOC) losses are approximately matched by greater C inputs to soil profiles, producing no net change in SOC stocks (Ziegler et al. 2017). Thus, though a warmer environment enhances these forests’ C cycling rates and results in greater rates of microbially mediated soil organic matter transformations, their SOC stocks appear resilient over the temperature range they represent.
Precipitation gradients also afford opportunity for soil studies at large spatial scales. Projections of future precipitation regimes have been used as a guide to design manipulative studies exploring soil C flux responses, given their mediation by biological forces measurable on shorter timescales. Multiple studies suggest both the sensitivity of soil CO2 fluxes to moisture regime, and to its modifications. For example, Miao et al. (2017) observed greater increases in soil respiration with precipitation increases than they did decreases in soil respiration with precipitation limitations. Tiemann and Billings (2011) observed release of heterotrophically derived CO2 from soils exposed to more intense, less frequent precipitation events of up to twice as much than control soils across a precipitation gradient in the Great Plains of North America; this pattern was most evident in soils from wetter regions. More recent work also emphasizes the importance of such climate legacy effects on soil respiratory responses: soils from wetter moisture regimes exhibit greater positive responses to moisture availability than soils from drier regions (Hawkes et al. 2017). Recent observations of rapid (i.e. yearly to decadal) structural responses of the soil fabric to climate (Hirmas et al. 2018) imply that small shifts in soil aggregate size with moisture changes likely influence the response of soil CO2 release to moisture changes.
1.3. RECENT EMPIRICAL INVESTIGATIONS OF SOIL RESPONSES TO ENVIRONMENTAL CONDITIONS AT DIVERSE SCALES: MINERAL WEATHERING
1.3.1. Mineral Weathering at the Column or Mesocosm Scale
The potential for SOC transformations to feedback to climate is intuitive, given the release of CO2 from soils that results from soil C dynamics. An additional, less frequently considered yet important feedback links the disciplines of soil organic matter transformations and climate: the relationship between SOC transformations and mineral weathering, which provides much of the nutrients needed for ecosystem productivity and associated climate regulation. Like investigations of soil organic matter transformations, studies of mineral weathering also take place at diverse scales (Figure 1.1). Work at relatively small scales is critical for defining fundamental rock weathering reaction kinetics. For example, organic ligand influences on mineral dissolution have been informed for decades by column experiments that reveal how pH and temperature drive elemental release from rock (Brantley 2008). The application of diverse organic acids to diverse rock types has demonstrated the importance of biotically produced acids as weathering agents (Bennett et al. 1988; Drever and Stillings 1997; Wang et al. 2005). Such studies have helped investigators infer environmental conditions in past climates across geologic timescales (Drever 1994). The precise mechanism by which organic acids induce mineral dissolution remains unknown (Hausrath et al. 2009), but studies such as these reveal reaction responses to environmental conditions to which real‐world, plot‐ or ecosystem‐scale behaviors can be compared.
Mesocosm‐scale experiments also provide demonstrations of potential climate forcings on rock weathering. Reaction kinetic theory indicates that fluid flow and residence time are the dominant controls on mineral weathering rates: under high fluid flow rates and short residence times, surface‐controlled reaction kinetics tend to control weathering rates, while under slow fluid rates and long residence times, transport‐controlled kinetics govern mineral weathering (e.g. Kump et al. 2000). However, translating this fundamental knowledge into relationships between flow rates and mineral dissolution is challenging because of apparent nonlinearities. For example, recent experiments of magnesite weathering in flow‐through columns demonstrate increases in dissolution of more than two orders of magnitude with a two order of magnitude increase in the flow rate (Salehikhoo et al. 2013). An additional, long standing challenge in simulating weathering fluxes across scale is the large discrepancy between the much faster laboratory‐measured weathering rates and field weathering rates (Malmstrom et al. 2000; White and Brantley 2003). Though the amount of water moving through the profile is a dominant driver of weathering rates, recent work has demonstrated that mineral heterogeneity and the overall contact of water with reactive surface areas are key phenomena controlling weathering rates as well (Moore et al. 2012; Wen and Li 2017). Thus, even if many natural reactions are transport controlled, as some investigators have suggested (Maher 2010), changes in climate that can induce changes in flow paths, the rate‐limiting step, or the value of the rate constant can alter chemical weathering rates.
1.3.2. Mineral Weathering at the Ecosystem to Landscape Scale Across Diverse Temporal Scales
Working across precipitation gradients can help us understand how hydrologic flows may influence weathering rates in a future climate. Precipitation gradients reveal that greater mean annual precipitation (MAP) induces greater mobility and losses of diverse elements (Kurtz et al. 2000; Dixon et al. 2016); in one study, a doubling of MAP was associated with an approximate doubling of the advance rate of profiles’ weathering front (Engel et al. 2016). Though projections of future precipitation patterns remain clouded in yet greater uncertainty than temperature regime shifts (e.g., Brunsell et al. 2010), multiple models suggest that future precipitation events, particularly in continental climates, may be less frequent and more intense (Easterling et al. 2000; Knapp et al. 2008). It is unclear how such changes may influence weathering patterns.
The influence of a warming climate on weathering reaction rates also is a key unknown for projections of Earth system feedbacks to climate. While it is well understood that silicate weathering rates increase with increasing temperature (Berner 1992), the sensitivity of mineral weathering rates to temperature is dependent upon the reaction kinetics and solubility. For example, minerals with low activation energies for dissolution such as biotite appear less sensitive to temperature changes relative to minerals with higher activation energies such as plagioclase (White et al. 1999). The net result of these differences in mineral weathering sensitivity to temperature is that effluent elemental ratios will change with temperature, such as K/Na in the case of biotite and plagioclase – an analogous scenario as that depicted by changing ratios of elements released during organic matter decay (Billings and Ballantyne 2013; Souza and Billings 2021). The observation of temperature‐induced changes in elemental ratios of weathered solutes in flow‐through column experiments helps explain why elemental ratios in stream water change under changing climatic conditions (White and Blum 1995).
Critically, temperature effects on mineral weathering rates exhibit an interaction effect with hydrologic flow regimes. This understanding requires investigators to integrate knowledge from flow controls on reaction kinetics and temperature effects on mineral dissolution. Mineral weathering rates tend to be driven more by the sensitivity of mineral solubility to temperature where flow regimes are relatively slow and transport‐controlled reaction kinetics dominate; under fast flow regimes, where surface‐controlled reaction kinetics tend to govern mineral weathering, the difference in the mineral activation energy plays a stronger role in the mineral weathering sensitivity to temperature change (Maher 2010).
Further complicating these phenomena, rock or mineral weathering rates could also be influenced indirectly by climate if changing climatic conditions alter rooting depths and/or abundances. Such changes could alter root organic acid production by changing root nutrient demand throughout the soil profile. Where nutrients are not derived from organic matter decay (Lambers et al. 2007), we would expect a shift with altered rooting depths in elemental release rates from mineral weathering. Such expectations are bolstered by work by Hausrath et al. (2009), who demonstrate that the application of citrate to powdered granite and basalt enhanced weathering release rates by approximately one order of magnitude in granite and by three to six times for basalt. Indeed, organic acid and CO2 production from root and microbial respiration can push natural systems farther from equilibrium and thus promote mineral weathering, though these effects may not be ubiquitous (e.g., Lawrence et al. 2015). Irrespective of temperature changes, enhancement of aboveground atmospheric CO2 can result in increased leaching of carbonic acid through soils as the biotic system responds to this influx of C, with yet‐unquantified influences on soil weathering rates (Oh and Richter 2004; Oh et al. 2007).
As with studies of organic matter transformations, studies of soil weathering responses to climate forcings at scales larger than the mesocosm often invoke a space‐for‐time substitution approach. For example, the Jemez‐Catalina, Boulder Creek, and Shale Hills Critical Zone Observatories compare soil properties and fluxes across contrasting aspects to infer ecosystem responses to energy inputs. Such studies offer one means with which to investigate the influence of climate on soil processes, because they explore how differences in energy inputs across ecosystem space – providing an imperfect but nonetheless useful analog to future climate change – can influence soil weathering processes. Working at the Jemez Catalina CZO, Pelletier et al. (2013) developed the Effective Energy and Mass Transfer (EEMT) concept, which provides a quantifiable metric of the energy available to promote weathering of bedrock. They report that north‐facing slopes exhibit higher EEMT than south‐facing slopes because of the greater moisture availability associated with relatively low radiation inputs (Pelletier et al. 2013). Farther north at the Boulder Creek CZO, north‐facing slopes also appear to have greater rates of bedrock weathering than south‐facing slopes. Here, the mechanism is linked to lower radiation on north‐facing slopes driving more intense frostcracking (Anderson et al. 2013), and likely to a greater degree of hydrologic connectivity and generally higher soil moisture on north‐facing slopes (Hinckley et al. 2014).
Consistent with these observations, north‐facing slopes exhibit greater elemental depletion compared to south‐facing slopes at the Susquehanna Shale Hills CZO. Here, in a relatively humid climate compared to Jemez‐Catalina and Boulder Creek, Ma et al. (2011) hypothesized that south‐facing slopes experience more rapid rates of erosion due to greater frequencies of wetting/drying and freeze/thaw cycles, limiting the time that soil is exposed to chemical weathering compared to soils on north‐facing slopes. An increased frequency of freeze/thaw cycles on south‐facing slopes at the SSHCZO has been invoked as promoting greater downslope movement of regolith by other investigators as well (West et al. 2014), and in spite of the greater degree of chemical depletion on north‐facing slopes, south‐facing slopes at the SSHCZO appear to experience greater rates of regolith production (Ma et al. 2013). Earthcasting results from Sullivan et al. (2020
