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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Serie: ASA, CSSA, and SSSA Books
- Sprache: Englisch
Explore the growing problem of soil salinity and sodicity and its impact on the environment, profitability, the human population, and soil resilience
In Salinity and Sodicity: A Global Challenge to Food Security, Environmental Quality, and Soil Resilience, a team of distinguished educators delivers an expert discussion of salinity and sodicity management. This book is designed to improve the problem-solving capabilities of students, soil health professionals, certified crop advisors, and other practicing professionals in this area.
In addition to an introduction to the causes of a rapidly growing problem, Salinity and Sodicity explores different measurement techniques, provides answers to common questions, provides potential solutions in a way that’s appropriate for introductory classes on soil salinity and sodicity management. It’s an ideal reference manual for professionals, as well as an effective tool for classrooms and crop advisor workshops.
Readers will also find:
- A thorough introduction to the use of supplemental irrigation and the impact of salts on the environment
- Comprehensive explorations of the economic considerations for farming problematic soils
- Practical discussions of the effects of salinity and sodicity on erosion and greenhouse gas emissions
- Practical case studies, problem sets, and an instructor answer key
Perfect for undergraduate, graduate, and doctoral students and certified and practicing soil professionals and advisors, Salinity and Sodicity will also benefit industry and academic researchers with an interest in soil salinity and sodicity in dryland regions.
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Veröffentlichungsjahr: 2024
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Scope
Reference
1 An Introduction to Salinity and Sodicity
Chapter Overview
Introduction
Salinity and Sodicity Basics
The Expanding Salinity and Sodicity Problem
Loss of Land
Summary
Chapter Questions
Acknowledgments
References
2 Salinity, the Silent Profit Killer
Chapter Overview
Introduction
Economic Considerations for Salinity Management
Financial Benefit to Treatment
Treatment Strategies and Economic Decision‐Making
Example on Using a Partial Budget to Assess Management Changes
Example of an Alternative Cropping Decision with a Break‐even Analysis
Example of Tile Drainage with Marginal Benefit Analysis
Example of Saline Irrigation with Dynamic Programming
Summary
Chapter Questions
Acknowledgment
References
3 Formation and Classification of Salt‐Affected Soils
Chapter Overview
Introduction
Common Pathways of Subsurface Salt Transport to the Soil Surface
Summary
Chapter Questions
Acknowledgments
References
4 Laboratory Methods for Determining Salinity and Sodicity
Chapter Overview
Salt‐Affected Soil Classification
Terms Used to Describe Salinity and Sodicity
Determining Electrical Conductivity for Soil Salinity
Total Dissolved Solids (TDS) for Soil Salinity
Measuring Soil Sodicity
Summary
Chapter Questions
Acknowledgments
References
5 Monitoring Soil Salinity and Water Content with Electromagnetic Sensors
Chapter Overview
Electromagnetic Sensors
Electromagnetic Properties of Soils
Measurement of Bulk Soil Electrical Conductivity
Temperature Correction
Calculation of Pore Water Electrical Conductivity
Hilhorst Equation for Pore Water Electrical Conductivity
Soil Water Solute Concentration
Example: Hydra Impedance Sensor Data from an Irrigated Alfalfa Field
Summary
Chapter Questions
Acknowledgment
References
6 Using Soil Sensors to Assess Soil Salinity
Chapter Overview
An Introduction to EM Sensors
Laboratory Measurements of EC
Field Measurements of Apparent Soil Electrical Conductivity (EC
a
)
The Seven Steps for Using an EC
a
Sensor to Assess Soil Salinity
Case Studies on the Use of EC
a
Information
Summary
Chapter Questions
Acknowledgments
References
7 Use of Models to Assess Salinity and Water Stress for Irrigated Corn (
Zea mays
) Production
Chapter Overview
Introduction
Determine the Question
Validation
Use and Interpretation of the Results
Summary
Chapter Questions
References
8 How to Use Remote Sensing to Identify Salt‐affected Soil
Chapter Overview
An Introduction to Remote Sensing
The Basics of the Electromagnetic Spectrum
Types of Sensors
Sensor Platforms
Landsat
Reflectance Patterns of Salt‐affected Soils
Creating A Roadmap for Using Remote Sensing for Assessing Soil Salinity
Vegetation Indices
Measuring Changes in Reflectance Characteristics
Using Machine Learning to Integrate Remote Sensing and Soil Data
Local‐ and Regional‐Scale Mapping
Summary
Chapter Questions
Acknowledgments
References
9 Plant Reponses to Salt Stress
Chapter Overview
Impact of Salt Stress on Plant Growth and Development
Salt Sensitivity and Plant Growth Stage
Physiological Salt Tolerance Mechanisms of Plants
Is There a Genetic Component to Tolerance That Could Be Exploited?
Summary
Chapter Questions
Acknowledgments
References
10 Native Plant Restoration of Salt‐impacted Soils
Chapter Overview
Introduction
Restoration Triangle
Focal Restoration Species
Practical Advice
Importance of Considering the Watershed
Ongoing Management and Future Land Use
Summary
Chapter Questions
Acknowledgments
References
11 Benefits of Phytoremediation when Repairing Salt‐affected Soils
Chapter Overview
Introduction
Phytoremediation Overview
How Does Phytoremediation Work?
Other Benefits of Phytoremediation
Summary
Chapter Questions
Acknowledgments
References
12 Water Management and Chemical Amendments in the Remediation of Saline and Sodic Soils
Chapter Overview
Introduction
Soil Testing and the Importance of the Na/EC Ratio
Water Management with Tile Drainage
Water Management with Deep Tillage
Chemical Amendments
Organic Amendments
Summary
Chapter Questions
Acknowledgments
References
13 An Introduction to Coastal Flooding Impact on Salinity and Sodicity in Agricultural Fields
Chapter Overview
Introduction
Salt Sprays and Cyclic Salts
Ocean Tides and Nuisance Flooding
Stormwater Surges
Tsunamis
Groundwater Saltwater Intrusion
Additive Effects of Sea Level Rise
Implications for Coastline Soils and Agricultural Production
Management
Summary
Chapter Questions
References
14 Greenhouse Gas Emissions from Salt‐Affected Soils
Chapter Overview
Introduction
Measuring GHG Emissions
Plants' Impact on GHG Emissions
Summary
Chapter Questions
Acknowledgments
References
15 Case Studies on Salt‐Affected Soil Remediation
Chapter Overview
Introduction to the Case Studies
Estimating the Amount of Irrigation Water That Should Be Applied to Prevent Increasing Soil EC
The Importance of Correctly Identifying a Saline/Sodic Problem and Solution
The Impact of Applying Gypsum and Irrigation Water to Reduce Salinity and Sodicity Problems in a California Fine Sandy Loam Soil
Using Gypsum, Drainage, and Tillage to Reduce Salinity and Sodicity Problems in a Poorly Drained Illinois Salt‐impacted Soil
Using Tile Drainage During a Period of Above‐average Rainfall to Reduce Soil EC
1:1
and %Na in a South Dakota Poorly Drained Saline/Sodic Soil
Combining Chemical Amendments with Green Manure and Organic Materials on the Restoration of Southern India Sodic Soils
The Use of Phytoremediation Combined with Chemical Amendment and Tillage to Remediate a Saline/Sodic Soil in Turkey
The Lack of Improvements to Corn, Soybean, and Sorghum Productivity When Chemical Amendments Were Used Alone in a Northern Great Plains Salt‐impacted Soil
The Beneficial Impact of Revegetating a Northern Great Plains Salt‐impacted Soil with Salt‐Tolerant Perennial Plants
The Importance of Managing a Groundwater Recharge Area
Managing Water in the Groundwater Recharge Area
The Impact of Installing Drip Irrigation and Subsurface Drainage to Expand the Amount of Productive Soil in a Chinese Marine System
Additional Discussion
Summary
Chapter Questions
Acknowledgments
References
16 Critical Questions About the Origins and Plant Responses to Soil Salinity and Sodicity
Chapter Overview
Salinity Origins and Creation of Salty Soils
Management of Salty Soils
Conducting Salt Tolerance Experiments
Plant Responses to Salts
Summary
Acknowledgments
References
Answer Key
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Global Distribution of Salt‐affected Soils by Region.
Chapter 2
Table 2.1 Soil salinity
C
50
and
p
values used in Equation (2.1) (Adapted fr...
Table 2.2 Revenue lost per acre due to salinity yield reduction.
Table 2.3 Partial budget for a change in tillage from a chisel plow to no‐t...
Table 2.4 Net present value of drain tile installation in terms of relative...
Table 2.5 Financial feasibility of a $129.50/acre payment over 10 years wit...
Chapter 4
Table 4.1 Classical EC
e
, SAR
e
, and ESP boundaries for the classification of...
Table 4.2 Saline, sodic, and saline‐sodic boundaries for management as iden...
Table 4.3 Impact of soil texture on the relationship between EC
1:1
and EC
e
....
Table 4.4 Effect of soil texture on electrical conductivity from a 1:1 soil...
Table 4.5 Conversions for electrical conductivity reported units to SI stan...
Table 4.6 Hypothetical result from a soil testing laboratory.
Chapter 8
Table 8.1 Band characteristics of sensors on Landsat 5, 8, and 9.
Table 8.2 Remote sensing reflectance indices commonly used in soil salinity...
Chapter 9
Table 9.1 The Threshold and Yield Losses per Increase in electrical conduct...
Chapter 12
Table 12.1 Influences of SAR
e
and EC
e
on Water Infiltration.
Table 12.2 Dryland Field Experiment Results After Applications of Gypsum on...
Chapter 14
Table 14.1 Cumulative CO
2
‐C and N
2
O‐N emissions over 7 days for three produ...
Table 14.2 Gene copies number for the
nirK
,
nirS
, and
nosZ
genes from plots...
Chapter 15
Table 15.1 The impact of gypsum rate and mixing depth on corn yields averag...
Table 15.2 Treatment impact on the mean across soil depths on soil pH, EC
e
,...
Table 15.3 The effect of the chemical treatment on tree survival and soil p...
Table 15.4 The total above ground biomass produced in the three productivit...
Chapter 16
Table 16.1 Classification of soil salinity based on the electrical conducti...
List of Illustrations
Chapter 2
Figure 2.1 Salt accumulation in a South Dakota production field.
Figure 2.2 Landsat images collected in 2004 and 2010 overlayed on the identi...
Figure 2.3 Calculated relative yields of various crops as affected by the el...
Figure 2.4 The revenue difference between barley, corn, soybean, and wheat w...
Figure 2.5 Revenue gains after the installation of drain tile for various in...
Chapter 3
Figure 3.1 A diagram showing the movement of water + dissolved ions to the s...
Figure 3.2 A diagram of the wick effect where salts move from the subsurface...
Figure 3.3 Saline seep. Saline and sodic soil formation by saline seep in th...
Figure 3.4 United States Geological Survey data of precipitation (purple lin...
Figure 3.5 Chloride ion depositions in the United States showing how far inl...
Figure 3.6 Houdek soil series and horizonation; scale is in feet. The soil p...
Figure 3.7 Dissection of the taxonomic name of the Houdek soil series.
Figure 3.8 Rendering of the Cresbard soil series and horizonation; scale on ...
Figure 3.9 Dissection of the taxonomic name of the Cresbard soil series. The...
Figure 3.10 Horizon designations and depth functions for clay (%), the elect...
Figure 3.11 Ekalaka series (coarse‐loamy, mixed, superactive, frigid Typic N...
Chapter 4
Figure 4.1 Examples of two types of soil electrical conductivity sensors: (a...
Figure 4.2 (a) Undersaturated sample. Does not glisten or flow. (b) Oversatu...
Figure 4.3 Soil electrical conductivity (EC) as influenced by the treatments...
Figure 4.4 Diagram showing the source of cations used in calculating the amm...
Chapter 5
Figure 5.1 (a) Examples of a time domain reflectometry (TDR) sensor (left), ...
Figure 5.2 Laboratory‐measured Hydra impedance sensor real and imaginary per...
Figure 5.3 (a) Hydra impedance sensor measured real permittivity, imaginary ...
Chapter 6
Figure 6.1 Inspecting a site for salinity and sodicity problems.
Figure 6.2 Apparent electrical conductivity (EC
a
) overlayed on an elevation ...
Chapter 7
Figure 7.1 Distributions of soil water electrical conductivity (EC
sw
) with s...
Figure 7.2 Distributions of soil water electrical conductivity (EC
sw
) with s...
Figure 7.3 Distributions of soil water electrical conductivity (EC
sw
) with s...
Chapter 8
Figure 8.1 Salt‐affected soil zone in a South Dakota field. In this image, t...
Figure 8.2 Electromagnetic spectrum of light as separated into different wav...
Figure 8.3 Reflectance of light on different objects.
Figure 8.4 (a) Salt‐affected soil in a wet season in April 2020 and (b) salt...
Figure 8.5 The northeast corner of the image is the salt‐affected area in th...
Figure 8.6 Unmanned aerial vehicle images of salt‐affected crop field soil (...
Figure 8.7 Unsupervised classified unmanned aerial vehicle images from a fie...
Chapter 9
Figure 9.1 A saline soil located in the North America Northern Great Plains....
Figure 9.2 General overview of salt stress effects on plant growth and devel...
Figure 9.3 Schematic representation of the impact of salt stress on water up...
Figure 9.4 Schematic illustration of the two‐phase growth response to salt s...
Figure 9.5 Impact of increasing salt stress on rice growth salt stress. From...
Figure 9.6 Categories for classifying crop salt tolerance to salinity accord...
Figure 9.7 (a) Plant cell with Na
+
and Cl
+
ions compartmentalized in...
Chapter 10
Figure 10.1 The restoration triangle for salt‐impacted soils.
Chapter 11
Figure 11.1 Image of water erosion that occurred following a <4‐cm rainfall ...
Figure 11.2 Five years after dormant seeding perennial grasses at a northern...
Chapter 12
Figure 12.1 The influence of changing sodium adsorption ratio (SA...
Figure 12.2 Single moldboard plow used for deep‐plowing Leptic, Typic, and G...
Figure 12.3 Conceptual drawing of gypsum application into a slot and roots u...
Chapter 13
Figure 13.1 Agricultural fields along the coastlines adjacent to tidal marsh...
Figure 13.2 Hypersaline soils along tidally influenced ditches lead to lack ...
Chapter 14
Figure 14.1 Images of a static greenhouse gas chamber (left) and continuous ...
Figure 14.2 Simplified soil C cycle. This cycle contains three categories th...
Figure 14.3 Methane production and soil temperatures over 7 days in July 201...
Chapter 15
Figure 15.1 Natural color image collected over the study area in 2004 (top) ...
Chapter 16
Figure 16.1 Cumulative water consumption related to water management strateg...
1
Figure 1 A schematic of the genes involved during nitrification/denitrificat...
Guide
Cover
Table of Contents
Series Page
Title Page
Copyright
Scope
Begin Reading
Answer Key
End User License Agreement
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EDITORS
Dr. David E. Clay is a former President of the American Society of Agronomy (2022), Editor‐in‐Chief of the American Society of Agronomy (2024), Distinguished Professor Soil Biogeochemistry, and the South Dakota Corn Council Endowed Chair of Precision Soybean Research and Promotion On‐Farm Research Program and has been actively involved in soil health research for 30 years He was the Editor for the Agronomy Journal and the South Dakota Corn Best Management Practice Manual, Soybean Best Management Practices Manual, and Wheat Best Management Practices manual. His research goal is to develop and test sustainable agricultural management systems that enhance environmental quality, maintain rural economies, and sustainably produce food while improving soil health. He teaches Introductory Soil Science, Environmental Soil Chemistry, and the Use of Sensors in Agriculture.
Dr. Thomas M. DeSutter received his PhD in 2004 from Kansas State University (Manhattan, KS). After completing a Post‐Doc with the USDA‐ARS (Ames, IA) he was hired in 2006 as an Environmental Soil Scientist by the Department of Soil Science at North Dakota State University (Fargo, ND). His primary research interests are saline and sodic soils, reclamation of energy‐extraction impacted soils, and instrumentation for measuring soil physical and biological parameters. DeSutter teaches Introductory to Soil Science, Soil and Land Use, and Environmental Field Instrumentation and Sampling and is the current Editor of Agricultural & Environmental Letters.
Dr. Sharon A. Clay is an agronomist with extensive experience in weed management research. She earned her BS in horticulture from the University of Wisconsin, Madison, her MS in plant science from the University of Idaho, and her PhD in agronomy from the University of Minnesota. She has investigated crop/weed interactions, studying their physiology, genomics, and examined the yield loss of different weeds on crops based on species, density, and time of emergence. She also examined site‐specific weed locations and emergence at the field level. With 35 MS students and 10 PhD students, research topics have ranged from examining weed impacts on teosinte (modern corn ancestor), mob grazing impacts to weed dynamics, and the use of perennial grasses to remediate salt‐impacted soils. She is a prolific author and editor, having published more than 200 scientific papers and contributed to several books. She has received four best paper awards, and numerous recognitions, including being elected as a fellow of the American Society of Agronomy (ASA) in 2009 and serving as ASA president in 2013. She was also honored with the Gamma Sigma International Distinguished Achievement in Agriculture Award in 2017.
Dr. Thandiwe Nleya is a Professor and Agronomist working on organic crop production, and management of cereal, oilseed, bioenergy and pulse crops. Dr. Nleya has over 15 years of conducting research on dryland cropping systems in the Northern Great Plains including the incorporation of cover crops, cereals, oilseeds, and legumes in dryland rotations. Her latest research has focused on remediation of saline/sodic soils including evaluation of a wide range of plant species for salt tolerance.
CONTRIBUTORS
Beverly Alvarez Torres
North Dakota State University
Fargo, ND
Email:
Dwarika Bhattarai
South Dakota State University
Department of Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
Abigail Blanchard
South Dakota State University,
Department of Natural Resource Management
Brookings, SD
Email:
Jose Pablo Castro Chacón
North Dakota State University,
School of Natural Resource Sciences and Soil Science
Fargo, ND
Email:
Jiyul Chang
South Dakota State University
Department of Agronomy, Horticulture and Plant Science
Brookings, SD
Email:
David E. Clay
Institution: South Dakota State University
Department: Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
Sharon A. Clay
South Dakota State University
Department of Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
Aaron Lee M. Daigh
University of Nebraska – Lincoln
Department Agrono>my & Horticulture; Biological Systems Engineering
Lincoln, Nebraska
Email:
Thomas M. DeSutter
North Dakota State University,
School of Natural Resource Sciences
Fargo, ND
Email:
Krista Ehlert
South Dakota State University,
West River Research & Extension, Department of Natural Resource Management
Rapid City, SD
Jorge F.S. Ferreira
USDA‐ARS,
Department of Agricultural Water Efficiency and Salinity Research Unit (US Salinity Laboratory)
Riverside, CA
Email:
Joleen C. Hadrich
,
University of Minnesota,
Department of Applied Economics
St. Paul, MN
Email:
Kyle P. Jore
University of Minnesota,
Department Natural Resources Science and Management & Department of Applied Economics
St. Paul, Minnesota
Email:
Thijs J. Kelleners
University of Wyoming,
Department of Ecosystem Science & Management
Laramie, WY
Email:
Joshua Leffler
South Dakota State University,
Department of Natural Resource Management
Brookings, SD
Email:
Brennan Lewis
South Dakota State University
Department of Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
Douglas Malo
South Dakota State University,
Department of Agronomy, Horticulture & Plant Science
Brookings, SD
Email: [email protected]
Chantel Mertz
North Dakota State University,
School of Natural Resource Sciences
Fargo, ND
Email:
Jarrod Miller
University of Delaware,
Department Plant and Soil Sciences
Georgetown, DE
Email:
Thandiwe Nleya
South Dakota State University
Department of Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
J.D. Oster
,
Emeritus Soil and Water Specialist, University of California,
Department of Environmental Sciences
Riverside CA 92521
Email:
Kristopher Osterloh
South Dakota State University,
Department of Agronomy, Horticulture & Plant Science
Brookings, SD
Email:
Shailesh Pandit
South Dakota State University,
Department of Agronomy, Horticulture, and Plant Science,
Brookings, SD
Email:
Lora Perkins
South Dakota State University,
Department of Natural Resource Management
Brookings, SD
Email:
Graig Reicks
South Dakota State University
Department of Agronomy, Horticulture, and Plant Science
Brookings, SD
Email:
Devinder Sandhu
USDA‐ARS,
Department of: Agricultural Water Efficiency and Salinity Research Unit (US Salinity Laboratory)
Riverside, CA
Email:
Donald L. Suarez
,
USDA‐ARS,
Department of Agricultural Water Efficiency and Salinity Research Unit (US Salinity Laboratory), Riverside, CA
Email:
Shaina Westhoff
South Dakota State University,
Department of Agronomy, Horticulture, Plant Science
Brookings, SD
Email:
EDITORIAL CORRESPONDENCE
American Society of Agronomy
Crop Science Society of America
Soil Science Society of America
5585 Guilford Road, Madison, WI 53711‐58011, USA
SOCIETY PRESIDENTS
Kristen S. Veum (ASA)
Kimberly A. Garland‐Campbell (CSSA)
Michael L. Thompson (SSSA)
SOCIETY EDITORS IN CHIEF
David E. Clay (ASA)
Bingru Huang (CSSA)
Craig Rasmussen (SSSA)
BOOK AND MULTIMEDIA PUBLISHING COMMITTEE
Girisha K. Ganjegunte (Chair)
Sangamesh V. Angadi
Xuejun Dong
Fugen Dou
Limei Liu
Shuyu Liu
Gurpal S. Toor
Sara Eve Vero
PUBLISHING STAFF
Matt Wascavage (Director of Publications)
Richard J. Easby (Content Strategy Program Manager)
Robert Gagnon (Copyeditor)
Salinity and Sodicity
Salinity and Sodicity A Global Challenge to Food Security, Environmental Quality, and Soil Resilience
David E. Clay, Thomas M. DeSutter, Sharon A. Clay, and Thandiwe Nleya, Editors
Copyright © 2024 American Society of Agronomy, Inc. / Crop Science Society of America, Inc. / Soil Science Society of America, Inc. All rights reserved.
Copublication by American Society of Agronomy, Inc. / Crop Science Society of America, Inc. / Soil Science Society of America, Inc. and John Wiley & Sons, Inc.
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, scanning, or otherwise, except as permitted by law. Advice on how to reuse material from this title is available at http://wiley.com/go/permissions.
The right of David E. Clay, Thomas M. DeSutter, Sharon A. Clay, and Thandiwe Nleya to be identified as the authors of this work/the editorial material in this work has been asserted in accordance with law.
Limit of Liability/Disclaimer of Warranty
While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy of completeness of the contents of this book and specifically disclaim any implied warranties or merchantability of fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The publisher is not providing legal, medical, or other professional services. Any reference herein to any specific commercial products, procedures, or services by trade name, trademark, manufacturer, or otherwise does not constitute or imply endorsement, recommendation, or favored status by the ASA, CSSA and SSSA. The views and opinions of the author(s) expressed in this publication do not necessarily state or reflect those of ASA, CSSA and SSSA, and they shall not be used to advertise or endorse any product.
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Scope
In the past, there has been many educational materials and much salinity research focused on irrigated agricultural systems in dryland soil. One of the more recent publications was, “Agricultural Salinity Assessment and Management” that was published by the Environmental Water Resource Institute (Wallender & Tanji, 2012). This book provides an excellent resource for irrigating systems, and it contains reference information on the effect of salts on soils, sampling and monitoring, diagnosis of salt problems, salinity management options, and reclamation treatment options. However, Wallender and Tanji (2012) only provides limited information on greenhouse gas emissions, flooding from rising sea levels, dryland systems and their remediation, phytoremediation, the use of remote sensing to track salt‐affected soils, and how climate change is impacting the expanding soil salinity/sodicity problem. In addition, Wallender & Tanji (2012) does not provide answers to common questions that can be integrated into lesson plans for undergraduate and graduate students. Our book was designed to complement as opposed to replace Wallender & Tanji (2012). Dryland non‐irrigated systems are a serious problem in many areas. In many situations it is driven by climate change and the transport of water and salts from buried marine sediments to the soil surface. In many situations, the soil surveys do not provide hints that salinity and sodicity are serious problems.
Our book covers a range of topics that include the origins of dryland salinity and sodicity, assessing the economic potential of remediation, problems with relying on soil mapping to identify problem areas quantification methods and procedures, management strategies, practical calculations, and more. The book also features special items including example problems set out as questions that are answered. These items are intended to empower the reader with new and updated knowledge about the growing problems caused by soil salinity and sodicity. The purpose of this book is to increase the problem‐solving abilities of students, soil professionals, certified crop advisors, and other practicing professionals.
Reference
Wallender, W. W., & Tanji, K. K. (2012).
Agricultural salinity assessment and management
, Second Edition ASCE Manual and Reports on Engineering Practices No. 71. ASCE American Society of Civil Engineers, Reston Virginia.
1An Introduction to Salinity and Sodicity
Shaina Westhoff, David E. Clay, Kristopher Osterloh, Sharon A. Clay, Thomas M. DeSutter, Thandiwe Nleya, Jorge F. S. Ferreira, Donald L. Suarez and Devinder Sandhu
Chapter Overview
Rising sea levels, increasing land use intensification, declining fresh water supplies, and climate variation are accelerating the development of saline and sodic soils worldwide. This chapter defines the issue and discusses the global extent of salt‐affected soils. Subsequent chapters are focused on saline/sodic soil economics (Chapter 2), formation and classification (Chapter 3), chemical analysis (Chapter 4), measurement with soil sensors (Chapters 5 and 6), monitoring salinity with models (Chapter 7), remote sensing (Chapter 8), plant responses to salt stress and phytoremediation (Chapters 9–11), chemical amendments (Chapter 12), rising sea levels (Chapter 13), greenhouse gas emissions (Chapter 14), and case studies (15). Chapter 16 provides answers to common questions.
Introduction
Salinity and sodicity are prevalent worldwide and have severe negative agronomic and environmental ramifications. Soil salinity is an accumulation of dissolved minerals and salts in soil that often includes Ca2+, Mg2+, Na+, K+, SO42−, Cl−, HCO3−, and NO3−. The sources of these salts are the dissolution of salt‐bearing minerals such as marine shales and halite, or human management that can add salts or accelerate soil genesis or lead to the accumulation of salts in to the surface soil. Salinity risks are generally assessed by measuring soil electrical conductivity (EC). However, because the critical EC levels are soil‐ and crop‐specific, salinity management is closely tied to water, soil, and crop management. Soil sodicity relates to the proportion of clay binding sites specifically filled by Na+. High concentrations of Na+ on the soil cation exchange (CEC) sites can contribute to soil dispersion and increase erosion, negatively affecting soil health and plant growth. Erosion not only leads to the loss of soil, but also the loss of any agronomic fertilizers or pesticides applied to the field. Therefore, erosion can be highly detrimental to surrounding ecosystem services while also severely reducing the producer's return on investment for impacted areas.
The management of salinity and sodicity have challenged communities since the beginning of agriculture (Jacobsen & Adams, 1958; Lowdermilk, 1953; Montgomery, 2007). One early challenge to food security was human‐induced salinization where the use of salt‐laden irrigation water reduced Sumerian harvests in the delta plain of the Tigris and Euphrates Rivers to one‐third of original production between 3000 and 1800 BCE (Montgomery, 2007). For these communities, farmers had the choice of abandoning the land or managing the problem. Because early farmers had an abundance of land but limited information/technology, many chose to move to new lands. Today the situation has changed with most of the earth's suitable land already in agricultural production, and with an increasing world population, management and reclamation are the only viable options for most communities.
Research suggests that if we do not mitigate this expanding problem, the combined impact of drought and salinity/sodicity have the potential to reduce yields on over 50% of global arable land by 2050 (Wang et al., 2003). Salt‐induced yield decreases are important because agriculture is the world's most essential industry and accounts for 27% of the world's labor force. Globally, between 2013 and 2018, the agricultural industry received almost $630 billion (US) in annual governmental support. Continued loss of arable lands due to salinity and sodicity will further strain global economies.
Salinity and Sodicity Basics
To understand salinity and sodicity, basic information is needed. For plant health, salinity risks are assessed by determining the soil EC. The EC of water extracted from a saturated paste extract is reported as ECe. Saline soils have an ECe ≥ 4 dS/m. This saturated paste method has been widely published and integrated into many recommendations. However, because the saturated paste extract approach is expensive, many commercial soil testing laboratories determine the EC of a soil‐water slurry. The slurry contains a specified amount of water and soil. If the slurry contains 10 mL of water and 2 g of soil, then the EC is reported as EC5:1 (Mattheese et al., 2017). Different laboratories use different ratios and methods. Generally, the measured EC value decreases with increasing amounts of water mixed with the soil. For example, Matthees et al. (2017) reported that the relationship between ECe and EC1:1 was, ECe = 0.14 + 2.26 EC1:1. If a soil test result states an EC1:1 of 2.5, the interpretation might be that the soil is non‐saline. However, when using the conversion from Matthees et al. (2017), the equivalent ECe for that soil would be ECe = 0.14 + 2.26(2.5) or 5.79 dS/m. Before making recommendations, consult with the laboratory about their protocols, make appropriate conversions. This calculated value changes the interpretation of the data from ‘crop growth will not be influenced’ to ‘yield decreases are expected’ for sensitive crops.
Salinity can also be measured in the field. Real‐time sensors such as the EM 38 (Geonics Limited) or the Veris MSP3 (Veris Technology) collect in‐field measurements. However, readings from these real‐time sensors are sensitive to changes in soil water content, bulk density, and temperature (Heiniger et al., 2003), and the values are reported as apparent electrical conductivity (ECa). Because the relationship between ECa and ECe are often location and sensor dependent, care should be used when converting ECa to ECe.
Sodicity is traditionally reported as the exchangeable sodium percent (ESP) which reflects the percentage of the soil cation exchange capacity occupied with Na+. Another traditional measurement of sodicity is the sodium adsorption ratio (SAR), which is based on the Na+, Ca2+, and Mg2+ concentrations within a saturated paste extract. Both ESP and SAR are expensive and time consuming for commercial labs to complete. A cost‐effective strategy to estimate the ESP or SAR is to determine the ratio between Na and cations extracted with ammonium acetate (%Na). The %Na value is a standard measurement in many commercial laboratories. Previous work shows that the SAR and %Na values are strongly correlated and often interchangeable (DeSutter et al., 2015).Traditionally, sodic soils have been classified as an ESP ≥ 15% or SAR ≥ 13 (Richards, 1954). However, work done in the Northern Great Plains has found clay dispersion and reductions in agronomic productivity can begin at SAR or %Na values as low as 5. Generally, the higher the ESP, SAR, or %Na value, the higher the risk of soil dispersion. In many soils, dispersion risks are highest in those with high ESP, SAR, or %Na and low EC values. Additional information is available in Chapters 5 and 6.
Saline‐sodic soils occur in areas with elevated salt concentration that also are high in Na+. To be classified as saline‐sodic, the soil would have an ECe ≥ 4 dS/m and an ESP ≥ 15%. However, in regions of the Northern Great Plains where dispersion has been observed at much lower Na+ concentrations, saline‐sodic soils have been observed at ECe ≥ 4 dS/m and %Na or SAR ≥ 5. All salt‐affected soils are difficult to manage and dispersed soil can have very low water infiltration rates. Management of saline‐sodic soils takes special care as an unsuitable management choice may accelerate the transition of that soil to purely sodic. More information on management can be found in Chapters 9–12.
The Expanding Salinity and Sodicity Problem
The world's land surface occupies approximately 149 million km2 (57.5 million mi2) or about 15 billion ha (37 billion ac) (Weast, 1968). Roughly 50% of the world's land mass is used for agricultural production (forest, pasture, and crops) with approximately 1 billion ha affected by salinity or sodicity ((FAO & ITPS, 2015; Rengasamy, 2006; Zaman et al., 2018)) (Table 1.1). Considering that the Earth's population is approximately 8 billion, the land equivalent (cropped area) is 0.0625 ha/person/yr (0.15 acre). The continued expansion of salinity and sodicity places many communities at risk as our land resource shrinks, but demand for food, feed, fiber, and fuel increases with the global population (FAO et al., 2022).
Table 1.1 Global Distribution of Salt‐affected Soils by Region.
Note. Adapted from FAO and ITPS (2015), Shahid et al. (2018), Enchanted Learning (2021). Data are reported in millions of hectares (m ha).
Continent/region
Saline soils
Sodic soils
Total salt affected
Total land area continent/region
Land area salt affected
World's total saline soil
World's total sodic soil
million ha
–%–
Africa
123
87
210
3007
6.9
29.1
13.6
Antarctica
NA
NA
NA
1321
NA
NA
NA
Australia/Oceania
18
340
358
769
46.6
4.3
53.2
Europe
9
21
30
994
3.0
2.1
3.2
Mexico/Central America
2
NA
2
249
0.8
0.5
NA
North America
a)
6
10
16
2041
0.7
1.4
1.5
North, Central, and East Asia
92
120
212
2891
7.3
21.8
18.8
South America
69
60
129
1782
7.2
16.3
9.4
South and western Asia
83
2
84
1112
7.6
19.7
0.3
Southeast Asia
20
NA
20
455
4.4
4.8
NA
World total
421
639
1,060
14,621
7.2
100
100
Abbreviations: NA, data not available.
a) Includes Greenland.
Human‐induced salinity resulting from poor irrigation management and the excessive use of fertilizers affects approximately 76 million ha (25%) of the 300 million ha of irrigated land worldwide (FAO & ITPS, 2015; Oldeman et al., 1991; Squires & Glenn, 2011). In these soils, common concerns are the limited amount of available irrigation water, not applying enough irrigation water to meet leaching requirements to wash the ions from the soil, and inadequate drainage. Almost half of the irrigation‐induced salinity is found in Asia (Pakistan, India, China, Iraq, Afghanistan, Turkey, Syria, Russia, and Kazakhstan) (Table 1.1). Significant human‐induced salinity resulting from decreasing supplies of high‐quality irrigation water are found in many other areas, including North America, Africa, Asia, and Australia.
Australia/Oceania has the largest extent of naturally occurring sodic soils, whereas Africa has the largest extent of naturally occurring saline soils. The specific cause for salinity and sodicity expansion varies by region. For example, in the North American Northern Great Plains, soil salinity and sodicity result from increasing rainfall and the conversion of native grasslands to row crop production. These environmental alterations facilitate greater capillary movement of Na+ and other ions from the underlying marine sediments to the soil surface. More details on specific natural and human‐accelerated pathways for saline/sodic soil formation are in Chapter 3. These situations have placed many highly productive soils at the tipping point of sustainability. Whatever the cause, salinity and sodicity have economic consequences, which are discussed in Chapter 2.
Loss of Land
The amount of agricultural land is finite; therefore, salinity and sodicity are critically important issues as both reduce the amount of arable land. For example, approximately 200 million ha of land have been affected by salinity in the southwestern United States and Mexico, whereas in Spain (Cañedo‐Argüelles et al., 2019), Portugal (Cruz & Silva, 2000), Tunisia (Kouzana et al., 2010), Greece (Vafidis et al., 2014), and Italy (Antonellini et al., 2008), the intrusion of saltwater into aquifers is a serious problem. In Africa, Australia, Asia, North America, and South America, the productivity of agricultural land has been constrained by climate change and secondary salinization. Secondary salinization occurs when the source of the salts result from irrigation or some other agricultural practice. According to some studies, it has been estimated that already productivity on 50% of the world's cultivated land is reduced by high salt concentrations (Massoud, 1981; Szabolcs, 1989; Butcher et al., 2016) and additional losses will continue to be observed in the future (Wang et al., 2003).
Summary
Salinity and sodicity have afflicted human civilization for thousands of years and continue to pose very serious economic, agronomic, and environmental threats to modern civilization. The scale of the issue makes it a problem of global importance and immediate relevancy. Salt‐affected soils form through numerous natural and human‐accelerated pathways. An understanding of these pathways is needed prior to implementing remediation techniques. For example, there are salts added with irrigation water, rising sea levels, grey water (wastewater that does not contain fecal materials), and road salts. Depending on the land manager and the specific situation, multiple management strategies for salinity and sodicity may be useful, but few will be available or feasible. To implement effective management tools, it is imperative that the land manager and crop advisor understand the source of salt‐accumulation for their specific situation, how salinity and sodicity numbers were derived in the laboratory, and how different salt quantification methods influence the reported values. Ultimately, as arable land area continues to decrease, the prevention, mitigation, and remediation of saline and sodic soils are the only options for preserving agricultural and environmental viability around the globe.
Chapter Questions
1.1
What factors are increasing the expansion of salt‐affected soils?
1.2
Why is it important that salinity and sodicity issues be addressed?
1.3
What are the differences among EC
e
, EC
5:1
, and EC
a
?
1.4
How is a saline soil different from a sodic soil? Is there a classification called a sodic soil?
Acknowledgments
Funding for this chapter was provided by South Dakota State University USDA‐ARS, North Dakota State University, South Dakota Corn Utilization Council, USDA‐AFRI (SD00G656‐16 and SD00H555‐15), and USDA‐NRCS‐CIG (69‐3A75‐285).
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2Salinity, the Silent Profit Killer
Kyle P. Jore and Joleen C. Hadrich
Chapter Overview
The accumulation of salt in soils has economic implications because management expenses increase whereas crop yields decrease. This chapter provides a framework for estimating crop yield losses using a modified discount response function. The crop yield changes are applied to a partial budget analysis framework to calculate the net change in profit for a farm transitioning a saline soil to a no‐till system as a treatment option. This chapter provides information on how to conduct a break‐even analysis to estimate the difference in revenue of various crop choices and a capital budget analysis to evaluate revenue and expense changes after installing drainage tile. Each strategy illustrates the short‐term and long‐term options for managing saline soil to help inform future management decisions moving forward. This chapter only focuses on saline soils, not sodic or saline‐sodic and it assumes that tile‐drainage will reduce soil EC and increase yields.
Introduction
Most agronomists recognize the presence of white crusty soil zones when scouting fields (Figure 2.1). These zones generally have very poor growth when seeded to annual crops. In addition to these obvious locations, there are many other areas where salinity will reduce yields. For example, Carlson et al. (2019) reported that sweet corn (Zea mays L.) yield losses generally are not observed when the electrical conductivity (EC) of a 1:1 soil/water mixture (EC1:1) is <0.79 dS/m and that a 27.8% yield loss occurs for each 1 dS/m increase above this value. However, different plants have different responses to salinity, and for soybean (Glycine max L.) yield reductions may not be observed if the EC1:1 is <2.34 dS/m (Carlson et al., 2019). Differences in the relationship between plants, suggests that financial returns from a remediation practice are crop or rotation specific.
When walking a field, it is easy to detect a crop failure but difficult to visually detect a 10% yield reduction due to salinity. Yields are reduced in saline soils because seed germination and plant growth are reduced (Franzen, 2007, Chapter 9). It is important to correctly diagnose the problem so that optimal management decisions can be implemented. Unfortunately, in many cases, the extent of salinity damage goes unnoticed because genetic improvements to some crops help to mask the problem. For example, growing sensitive crops in rotation with less sensitive crops can lead to low yields when non‐resistant plants are grown and relatively high yields when salt‐tolerant plants are grown. Other problems with growing salt‐tolerant crops in rotation are (a) the size of the effected zones are not known and (b) the farmer does not understand the viable options. To maximize potential farmland revenue, every farm manager should look out for this silent profit killer.
To quantify the amount of damage and to determine if a specific treatment is a good financial investment, we start with identifying the extent and magnitude of the problem. This may include a reconnaissance that identifies problem areas by overlaying a remote sensing image (Figure 2.2) with apparent EC (ECa) maps on a digital elevation model. For example, by comparing multiple dates, the rate of expansion can be estimated. The second step is to determine the different management options that can be used to remediate the problem, and the third step is to determine the return on the investment on those options (Knapp, 2012; Knapp & Dinar, 1988).
Figure 2.1 Salt accumulation in a South Dakota production field.
Dwarika Bhattarai, South Dakota State University, Brookings, SD.
Figure 2.2 Landsat images collected in 2004 and 2010 overlayed on the identical field. White areas in the field are zones where salts have accumulated in the surface soil.
Carlson.
Economic Considerations for Salinity Management
Evaluating tradeoffs is fundamental to the theory of economics. In the context of management, costly decisions are considered an appropriate choice if they produce a greater benefit than the expense. Before any analysis can begin, the scope and magnitude of the problem must be identified. This often involves collecting and analyzing soil samples for EC, pH, soil texture, and appropriate cations and anions. It is also useful to understand the yield reductions in these areas and the potential benefits from implementing an improvement plan. Establishing a baseline and benefits is a good starting point.
Undoubtedly, the economic objective for any farm manager is to maximize profit subject to the components of the production process that can be changed. For example, crop selection, tillage method, or amount of irrigation are all potentially variable components. We will not consider the option of selling or renting out saline farmland; however, this may be a strategy worth exploring if you have the capital resources to move your farming location.
Because saline soil involves a high concentration of soluble salts that have varying effects on different plants, salinity management is closely tied to water and crop management. There are several ways that a farmer can manage water, with some management practices being more costly than others. For example, a salinity (high EC) problem may be solved by installing a tile drainage system by switching from planting an EC‐sensitive crop to an EC‐tolerant crop. Soybean and wheat (Triticum aestivum L.) are moderately tolerant, and sugar beet (Beta vulgaris var. saccharifera) is salt tolerant (Carlson et al., 2019). A second alternative would be to compare the cost/benefit ratio for installing drainage while also switching the crop from a low‐ to high‐water‐use rotation. Therefore, a more refined economic objective would be to maintain desired soil salinity levels through water and/or agronomic management practices that maximize profit.
There are several important ancillary benefits associated with salinity management. These benefits include reduced erosion, reduced emissions of important greenhouse gases, and improved root development (Fiedler et al., 2021). Before we proceed it is important to point out some of the inherent uncertainties with economic analysis. First, yield reductions or gains only make sense if yield expectations are known. Second, uncertainties exist with commodity prices. Third, costs are dependent on estimates, and the actual costs for the raw materials and labor vary with time. Many of these uncertainties can be minimized by using software that estimates return on investments for different crop responses and price scenarios. What about markets? if no market (or distance to market is too far) then may not be a ‘realistic’ choice even if the crop is salt tolerant.
Financial Benefit to Treatment
The use of land for agricultural production has one primary purpose: to generate value for the landowner. Although this might be in the form of food for consumption, in many agricultural production systems it is producing commodities that generate revenue or income. When someone says that a certain tract of land is low yielding, it is likely the case that the farmer needs to change what they produce, take the land out of production, or remediate the soil. Fortunately, in the case of salinity, soil remediation is a viable option to reclaim or improve yield.
To understand the effect of salinity on yields we will use a modified discount response function model (van Genuchten & Gupta, 1993). Equation (2.1) (modified discount response function) was introduced by van Genuchten & Gupta (1993) and parameterized with data on crop response to salinity modified from Steppuhn et al. (2005). Because the equation does not account for low‐salinity yield loss, we will not be using the linear response function from Maas & Hoffman (1977). However, there may be times when the linear model would be preferred, such as finding break‐evens for alternative crops.
Because crops respond differently in different soils, we will assume that we can model growth with the model
where C50 and p are empirical constants. The C50 value is the point where yield is reduced 50%, and p denotes the steepness of the decrease. The higher the p value, the steeper the yield loss, and C is the initial EC value. The values used here are best estimates and should not be assumed to fit in all scenarios. The C50 and p values for selected crops are given in Table 2.1.
Table 2.1 Soil salinity C50 and p values used in Equation (2.1) (Adapted from Steppuhn et al., 2005).
Crop name
EC
e
value at
C
50
p
shape
dS/m
Barley
7.51
2.18
Corn
5.54
2.75
Rye
15.84
5.76
Soybean
7.16
8.85
Sugar beet
15.04
3.86
Sunflower
14.37
2.99
Wheat
5.36
3.67
Abbreviations: C50, the point where yield is reduced 50%; ECe, electrical conductivity of water extracted from a saturated paste extract; p, steepness of the decrease.
The relative yields of different crops as affected by the EC of water extracted from a saturated paste extract (ECe) are shown in Figure 2.3. The data provided by Steppuhn et al. (2005) suggest that corn, wheat, and barley (Hordeum vulgare L.) have rapid yield losses with increasing ECe and that as ECe exceeds 5 dS/m, soybean crops are affected more than sunflower (Helianthus annuus L.), sugar beet, and rye (Secale cereale L.). These types of data can be used to develop a crop yield to soil salinity profile.
Figure 2.3 Calculated relative yields of various crops as affected by the electrical conductivity of water extracted from a saturated paste extract (ECe). The relative yields were determined using Equation (2.1) and
data from Table 2.1.
To determine the total revenue loss due to salinity, multiply a given commodity price and yield expectation by the portion of yield lost.
Based on Equation (2.2) and Figure 2.3, revenue loss was calculated for soils with different ECe values (Table 2.2). As one would expect, revenue loss follows closely with crop salt tolerance. This analysis showed that corn revenue was reduced by relatively small increases in ECe and that corn revenue loss was greater than soybean revenue loss at ECe values <8 dS/m (e.g., at ECe = 6 corn yield loss = 50% [Figure 2.3] and revenue loss of −$377.13/acre (−$931.92/ha) [Table 2.2], whereas soybean yield loss is <10% and revenue loss is $108.99/acre ($269.32/ha)). This information can also be used to determine the revenue loss for different crop rotations. For example, a crop rotation that includes corn, soybean, and wheat would be −$93.66/acre at an ECe value of 4 dS/m (sum of each crop and divide by 3 for the 3‐year rotation).
Table 2.2 Revenue lost per acre due to salinity yield reduction.
Soil salinity
Crop
Expectation
EC
e
= 4
EC
e
= 6
EC
e
= 8
Wheat
70 bu/acre @ $4.50/bu
−$80.20
−$189.63
−$256.10
Corn
200 bu/acre @ $3.40/bu
−$197.13
−$377.13
−$498.51
Soybean
60 bu/acre @ $10.50/bu
−$3.65
−$108.99
−$458.33
Abbreviation: ECe, electrical conductivity of water extracted from a saturated paste extract.
