Building Soils for Better Crops « ศาสตร์เกษตรดินปุ๋ย

Published in 2009 by the Sustainable Agriculture Research and Education (SARE) program,with funding from the National Institute of Food and Agriculture, U.S. Department of Agriculture

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

This book was published by the Sustainable Agriculture Research
and Education (SARE) program under cooperative agreements with
USDA’s National Institute of Food and Agriculture, University of
Maryland and University of Vermont.
To order:
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Library of Congress Cataloging-in-Publication Data
Magdoff, Fred, 1942-
Building soils for better crops : sustainable soil management / by
Fred Magdoff and Harold van Es. — 3rd ed.
p. cm. — (Handbook series ; bk. 10)
Includes bibliographical references and index.
ISBN 978-1-888626-13-1
1. Soil management. 2. Humus. I. Van Es, Harold, 1958- II.
Sustainable Agriculture Research & Education (Program) III. Title.
IV. Series: Sustainable Agriculture Network handbook series ; bk. 10.
S592.8.M34 2009
631.4–dc22
2009031856
Every effort has been made to make this book as accurate as possible.
This text is only a guide, however, and should be used in conjunction
with other information sources on crop, soil, and farm management.
The editors, authors, and publisher disclaim any liability, loss, or risk,
personal or otherwise, that is incurred as a consequence, directly or
indirectly, of the use and application of any of the contents of this book.
Mention, visual representation, or inferred reference of a product, service,
manufacturer, or organization in this publication does not imply
endorsement by USDA, the SARE program, or the authors. Exclusion
does not imply a negative evaluation.
The opinions expressed in this book do not necessarily reflect the
opinions of the SARE program or USDA.
Authors: Fred Magdoff and Harold van Es
Contributing Writer (farmer profiles): Amy Kremen
Production Manager: Dena Leibman
Copy Editing: Jill Mason
Graphic Design: Kirsten Ankers
Cover Illustration: Frank Fretz
Indexing: Jill Mason
Printing: Printed by Linemark Printing using 100% wind power on
process-chlorine-free, 100% post-consumer-waste paper.

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

——————————

Contents
About the Authors…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… v
About SARE ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….. vii
Preface………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….. ix
Introduction ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. xi
PART ONE OR GANIC MATTER —THE KEY TO HE ALTH Y SO ILS
1 Healthy Soils………………………………………………………………………………………………………………………………………………………………………………………………. 3
2 Organic Matter: What It Is and Why It’s So Important……………………………………………………………………………………………………………….. 9
3 Amount of Organic Matter in Soils……………………………………………………………………………………………………………………………………………………… 23
4 The Living Soil…………………………………………………………………………………………………………………………………………………………………………………………… 37
PART TWO PHYSICAL PRO PERT IES AND NUTR IENT CYCLES
5 Soil Particles, Water, and Air………………………………………………………………………………………………………………………………………………………………… 49
6 Soil Degradation: Erosion, Compaction, and Contamination……………………………………………………………………………………………………. 57
7 Nutrient Cycles and Flows……………………………………………………………………………………………………………………………………………………………………… 69
PART THREE ECO LOGICAL SO IL MANAGEMENT
8 Soil Health, Plant Health, and Pests…………………………………………………………………………………………………………………………………………………… 77
9 Managing for High-Quality Soils: Organic Matter, Soil Physical Condition, Nutrient Availability………………………………… 87
10 Cover Crops………………………………………………………………………………………………………………………………………………………………………………………………… 101
11 Crop Rotations…………………………………………………………………………………………………………………………………………………………………………………………… 115
12 Animal Manures for Increasing Organic Matter and Supplying Nutrients…………………………………………………………………………….. 129
13 Making and Using Composts………………………………………………………………………………………………………………………………………………………………… 141
14 Reducing Erosion and Runoff………………………………………………………………………………………………………………………………………………………………. 153
15 Preventing and Lessening Compaction……………………………………………………………………………………………………………………………………………… 161
16 Reducing Tillage……………………………………………………………………………………………………………………………………………………………………………………….. 173
17 Managing Water: Irrigation and Drainage……………………………………………………………………………………………………………………………………….. 187
18 Nutrient Management: An Introduction…………………………………………………………………………………………………………………………………………… 203
19 Management of Nitrogen and Phosphorus………………………………………………………………………………………………………………………………………. 213
20 Other Fertility Issues: Nutrients, CEC, Acidity, and Alkalinity…………………………………………………………………………………………………… 227
21 Getting the Most from Routine Soil Tests…………………………………………………………………………………………………………………………………………. 235
PART FOUR PUTT ING IT ALL TO GETHER
22 How Good Are Your Soils? Field and Laboratory Evaluation of Soil Health………………………………………………………………………….. 257
23 Putting It All Together…………………………………………………………………………………………………………………………………………………………………………….. 267
Glossary…………………………………………………………………………………………………………………………………………………………………………………………………………………………….. 277
Resources…………………………………………………………………………………………………………………………………………………………………………………………………………………………… 283
Index ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………. 287

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Building Soils for Better Crops, 3rd Edition
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——————————

Ab out the Authors
Fred Magdoff is emeritus professor of plant and soil science at the University of Vermont
and adjunct professor at Cornell University. He was Plant and Soil Science Department chair
for eight years and for two decades was the coordinator of the twelve-state Northeast Region
for the U.S. Department of Agriculture’s Sustainable Agriculture Research and Education
(SARE) program. He is also a fellow of the American Society of Agronomy. He has worked on
soil testing for nitrogen and phosphorus, the effects of manures on soil properties and crop
yields, buffering of soil pH, and many other issues related to soil health. He lives in Burlington
and Fletcher, Vermont, with his wife, dog, two cats, a large garden, an occasional flock of
chickens, and a small herd of beef cows.
Harold van Es is a professor of soil science at Cornell University and serves as chair of the
Department of Crop and Soil Sciences. Born in Amsterdam, Netherlands, he grew up in an
environment where soil and water are critical issues. His current research focuses on soil
health, computational agriculture, and environmental statistics. He teaches courses in soil
management and space-time statistics and also leads an extension program. He is a fellow
of the Soil Science Society of America and the American Society of Agronomy. He lives in
Lansing, New York, with his wife, three children, and two cats.

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

——————————

Ab out SARE
SARE is a grant-making and outreach program. Its mission is to advance—to the whole of American agriculture—
innovations that improve profitability, stewardship, and quality of life by investing in groundbreaking research and
education.
Since it began in 1988, SARE has funded more than 4,000 projects around the nation that explore innovations, from
rotational grazing to direct marketing to cover crops—and many other best practices. Administering SARE grants are
four regional councils composed of farmers, ranchers, researchers, educators, and other local experts, and coordinators
in every state and island protectorate run education programs for ag professionals. SARE Outreach publishes practical
books, bulletins, online resources, and other information for farmers and ranchers. All of SARE’s activities are funded by
the National Institute of Food and Agriculture, U.S. Department of Agriculture.
Guided by the belief that healthy soil is the foundation of healthy agriculture, SARE has made soil quality research
and education a cornerstone of its project portfolio—and made Building Soils for Better Crops one of its signature
handbooks. This new, all-color edition is an authoritative text on soil health, detailing the latest research and experiences
of soil scientists—many of whom are SARE grant participants, including the book’s authors. Some other SARE
titles that might be of interest to Building Soils readers: (Books) Managing Cover Crops Profitably, third edition;
The New American Farmer, second edition; (Bulletins) Diversifying Cropping Systems; How to Conduct Research
on Your Farm or Ranch; Transitioning to Organic Production; Smart Water Use on Your Farm or Ranch.
For more information about SARE’s grant-making program and information products, visit www.sare.org or contact:
SARE Outreach Associate, 10300 Baltimore Ave., BARC, Bldg. 046, Beltsville, MD 20705; info@sare.org; (301) 504-5236.
SARE Regi ons
SARE’s four regional offices and outreach office work to advance sustainable innovations to the whole of American agriculture

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Building Soils for Better Crops, 3rd Edition
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——————————

Preface
Used to be anybody could farm. All you needed was a strong back . . . but nowadays you need a good
education to understand all the advice you get so you can pick out what’ll do you the least harm.
—VER MONT SAYING , MID -1900S

We have written this book with farmers, farm advisors,
students, and gardeners in mind, although we have
also found copies of earlier editions on the bookshelves of
many of our colleagues. Building Soils for Better Crops
is a practical guide to ecological soil management that
provides background information as well as details of
soil-improving practices. This book is meant to give the
reader a holistic appreciation of the importance of soil
health and to suggest ecologically sound practices that
help to develop and maintain healthy soils.
Building Soils for Better Crops has evolved over time.
The first edition focused exclusively on the management
of soil organic matter. If you follow practices that
build and maintain good levels of soil organic matter,
you will find it easier to grow healthy and high-yielding
crops. Plants can withstand droughty conditions better
and won’t be as bothered by insects and diseases. By
maintaining adequate levels of organic matter in soil, you
have less reason to use as much commercial fertilizer,
lime, and pesticides as many farmers now purchase. Soil
organic matter is that important.
Organic matter management was also the heart of the
second edition, but we decided to write a more comprehensive
guide that includes other essential aspects of
building healthy soils, such as managing soil physical
properties and nutrients, as well as a chapter on evaluating
soil health (chapter 22). In addition, we updated
farmer case studies and added a new one. The case studies
describe a number of key practices that enhance the
health of the farmers’ soils.
Many chapters were rewritten, expanded, and reorganized
for the third edition—some completely. A chapter on
physical properties and issues was divided into two (chapters
5 and 6), and chapters were added on the principles of
ecological soil management (chapter 8) and on irrigation
and drainage (chapter 17). The third edition, while still
focusing on farming and soils in the United States, has a
broader geographical scope; the book has evolved into a
more comprehensive treatise of sustainable soil management
for a global audience. We have, however, maintained
the use of English units in the book for the convenience
of our original target audience, although many readers
outside North America—and scientists like us—would
perhaps prefer the use of metric units.
A book like this one cannot give exact answers to
problems on specific farms. In fact, we are purposely
staying away from recipe-type approaches. There are just
too many differences from one field to another, one farm
to another, and one region to another, to warrant blanket
recommendations. To make specific suggestions, it is

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Building Soils for Better Crops, 3rd Edition
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necessary to know the details of the soil, crop, climate,
machinery, human considerations, and other variable
factors. Good soil management needs to be adaptive and
is better achieved through education and understanding
than with simple recommendations.
Over many centuries, people have struggled with
the same issues we struggle with today. We quote some
of these people in many of the epigraphs at the beginning
of each chapter in appreciation for those who have
come before. Vermont Agricultural Experiment Station
Bulletin No. 135, published in 1908, is especially fascinating;
it contains an article by three scientists about the
importance of soil organic matter that is strikingly modern
in many ways. The message of Edward Faulkner’s
Plowman’s Folly—that reduced tillage and increased use
of organic residues are essential to improving soil—is
as valid today as in 1943 when it was first published.
And let’s not forget the first textbook of soil management,
Jethro Tull’s A Horse-Hoeing Husbandry, or an
Essay on the Principles of Tillage and Vegetation, first
published in 1731. Although it discusses now-refuted concepts,
like the need for intensive tillage, it contains the
blueprints for modern seed drills. The saying is right—
what goes around comes around. Sources are cited at the
end of each chapter and at the end of the book, although
what’s provided is not a comprehensive list of references
on the subject.
Many people reviewed individual chapters or the
entire manuscript at one stage or another and made
very useful suggestions. We would like to thank George
Abawi, William Brinton, Andy Clark, Bill Cox, Karl
Czymmek, Heather Darby, Addy Elliott, Charles Francis,
Tim Griffin, Joel Gruver, Karl Hammer, Jon Hanson,
Ellen Harrison, John Havlin, Robert L. Hill, Bruce
Hoskins, Bill Jokela, Doug Karlen, Ann Kennedy, Charles
Mitchell, Jr., Tom Morris, John Peters, Stu Pettygrove,
Marianne Sarrantonio, John Sawyer, Eric Sideman, Gene
Stevens, Jeff Strock, and Ray Weil.
We recognize colleagues who provided photos in
the figure captions, and we are grateful for their contribution.
All other photos are our own or in the public
domain. We also acknowledge some of our colleagues—
Bob Schindelbeck, George Abawi, David Wolfe, Omololu
(John) Idowu, Ray Weil, and Rich Bartlett (deceased)—
whose ideas and insights have helped shape our understanding
of the subject. And we thank our wives, Amy
Demarest and Cindy van Es, for their patience and
encouragement during the writing of this book. Any
mistakes are, of course, ours alone.
— Fred Magdoff
Professor Emeritus
Department of Plant & Soil Science
University of Vermont
— Harold van Es
Professor and Chair
Department of Crop & Soil Sciences
Cornell University
June 2009

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——————————

Introduction
… it is our work with living soil that provides sustainable alternatives to the triple crises of climate, energy,
and food. No matter how many songs on your iPod, cars in your garage, or books on your shelf, it is plants’
ability to capture solar energy that is at the root of it all. Without fertile soil, what is life?
—VANDANA SHI VA, 2008

Throughout history, humans have worked the fields,
and land degradation has occurred. Many civilizations
have collapsed from unsustainable land use, including
the cultures of the Fertile Crescent in the Middle East,
where the agricultural revolution first occurred about
10,000 years ago. The United Nations estimates that 2.5
billion acres have suffered erosion since 1945 and that
38% of global cropland has become seriously degraded
since then. In the past, humankind survived because
people developed new lands. But a few decades ago the
total amount of agricultural land actually began to decline
as new land could no longer compensate for the loss of
old land. The exhaustive use of land is combined with
increasing populations; greater consumption of animal
products produced in large-scale facilities, which creates
less efficient use of crop nutrients; expanding acreages
for biofuel crops; and the spread of urban areas, suburban
and commercial development, and highways onto
agricultural lands. We have now reached a point where
we are expanding into marginal lands—like shallow
hillsides and arid areas—that are very fragile and can
degrade rapidly (figure I.1). Another area of agricultural
expansion is virgin tropical rainforests, which are the last
remnants of unspoiled and biologically rich land. The
rate of deforestation at this time is very disconcerting;
if continued at this level, there will be little virgin forest
left by the middle of the century. We must face the reality
that we are running out of land. We have already seen
hunger and civil strife—especially in Africa—over limited
land resources and productivity, and a global food crisis
break out in 2008. Some countries with limited water
or arable land are purchasing or renting land in other
countries to produce food for the “home” market.
Nevertheless, human ingenuity has helped us
overcome many agricultural challenges, and one of the
truly modern miracles is our agricultural system, which
produces abundant food. High yields often come from
the use of improved crop varieties, fertilizers, pest control
products, and irrigation, which have resulted in food
security for much of the developed world. At the same
time, mechanization and the ever-increasing capacity of
field equipment allow farmers to work increasing acreage.
Despite the high productivity per acre and per person,
many farmers, agricultural scientists, and extension specialists
see severe problems associated with our intensive
agricultural production systems. Examples abound:
• With conventional agricultural practices heavily
dependent on fossil fuels, the increase in the price of

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energy—as well as the diversion of crops to produce
ethanol and biodiesel and other trends—will cause
food prices to be higher in the future, resulting in a
worldwide upsurge in hunger.
• Too much nitrogen fertilizer or animal manure
sometimes causes high nitrate concentrations in
groundwater. These concentrations can become high
enough to pose a human health hazard. Many of the
biologically rich estuaries and the parts of seas near
river inflows around the world, including the Gulf of
Mexico, are hypoxic (have low oxygen levels) during
late summer months due to nitrogen enrichment from
agricultural sources.
• Phosphate and nitrate in runoff and drainage water
enter water bodies and degrade their quality by
stimulating algae growth.
• Antibiotics used to fight diseases in farm animals can
enter the food chain and may be found in the meat we
eat. Perhaps even more important, their overuse on
farms where large numbers of animals are crowded
together has resulted in outbreaks of human illness
from strains of disease-causing bacteria that have
become resistant to many antibiotics.
• Erosion associated with conventional tillage and
lack of good rotations degrades our precious soil and,
at the same time, causes the silting up of reservoirs,
ponds, and lakes.
• Soil compaction reduces water infiltration and
increases runoff, thereby increasing flooding, while
at the same time making soils more drought prone.
• In some parts of the country groundwater is
being used for agriculture faster than nature can
replenish this invaluable resource. In addition,
water is increasingly diverted for urban growth in
dry regions of the country, lessening the amount
available for irrigated agriculture.
The whole modern system of agriculture and food is
based on extensive use of fossil fuels—to make and power
large field equipment, produce fertilizers and pesticides,
dry grains, process food products, and transport them
over long distances. With the price of energy so much
greater than just a few years ago, the economics of the
“modern” agricultural system may need to be reevaluated.
The food we eat and our surface and groundwaters are
sometimes contaminated with disease-causing organisms
and chemicals used in agriculture. Pesticides used to
control insects and plant diseases can be found in foods,
animal feeds, groundwater, and surface water running off
agricultural fields. Farmers and farm workers are at special
risk. Studies have shown higher cancer rates among
those who work with or near certain pesticides. Children
in areas with significant usage of pesticides are also at
risk of having developmental problems. When considered
together, these inadvertent by-products of agriculture are
huge. The costs of all these negative effects on wildlife,
natural resources, human health, and biodiversity in
the United States is estimated at between $6 billion and
$17 billion per year. The general public is increasingly
demanding safe, high-quality food that is produced without
excessive damage to the environment—and many are
willing to pay a premium to obtain it.
To add to the problems, farmers are in a perpetual
struggle to maintain a decent standard of living. As
consolidations and other changes occur in the agriculture
input (seeds, fertilizers, pesticides, equipment, etc.), food
processing, and marketing sectors, the farmer’s bargaining
position weakens. For many years the high cost of
purchased inputs and the low prices of many agricultural
commodities, such as wheat, corn, cotton, and milk, caught
farmers in a cost-price squeeze that made it hard to run
a profitable farm. At the time of writing this edition, the
prices for many agricultural commodities have recently
seen sharp increases and then a rapid decrease. On the
other hand, the costs of purchased inputs also increased
greatly but then did not decrease as much as crop prices
did. The wide swings in prices of crops and animal products
have created a lot of stress among farmers.
Given these problems, you might wonder if we should

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continue to farm in the same way. A major effort is under
way by farmers, extension educators, and researchers to
develop and implement practices that are both more environmentally
sound than conventional practices and, at
the same time, more economically rewarding for farmers.
As farmers use management skills and better knowledge
to work more closely with the biological world and the
consumer, they frequently find that there are ways to
increase profitability by decreasing the use of inputs purchased
off the farm and selling direct to the end-user.
Soi l Hea lth Inte gra l to Sustaina ble Agri culture
With the new emphasis on sustainable agriculture
comes a reawakening of interest in soil health. Early
scientists, farmers, and gardeners were well aware of the
importance of soil quality and organic matter to the productivity
of soil. The significance of soil organic matter,
including living organisms in the soil, was understood
by scientists at least as far back as the 17th century. John
Evelyn, writing in England during the 1670s, described
the importance of topsoil and explained that the productivity
of soils tended to be lost with time. He noted that
their fertility could be maintained by adding organic
residues. Charles Darwin, the great natural scientist of
the 19th century who developed the modern theory of
evolution, studied and wrote about the importance of
earthworms to the cycling of nutrients and the general
fertility of the soil.
Around the turn of the 20th century, there was
again an appreciation of the importance of soil health.
Scientists realized that “worn-out” soils, whose productivity
had drastically declined, resulted mainly from the
depletion of soil organic matter. At the same time, they
could see a transformation coming: Although organic
matter was “once extolled as the essential soil ingredient,
the bright particular star in the firmament of the
plant grower, it fell like Lucifer” under the weight of
“modern” agricultural ideas (Hills, Jones, and Cutler,
1908). With the availability of inexpensive fertilizers and
larger farm equipment after World War II, and the availability
of cheap water for irrigation in some parts of the
western United States, many people working with soils
forgot or ignored the importance of organic matter in
promoting high-quality soils.
As farmers and scientists were placing less emphasis
on soil organic matter during the last half of the
20th century, farm machinery was getting larger. More
horsepower for tractors allowed more land to be worked
by fewer people. Large four-wheel-drive tractors allowed
farmers to do field work when the soil was wet, creating
severe compaction and sometimes leaving the soil
in a cloddy condition, requiring more harrowing than
otherwise would be needed. The use of the moldboard
plow, followed by harrowing, broke down soil structure
and left no residues on the surface. Soils were left
bare and very susceptible to wind and water erosion.
New harvesting machinery was developed, replacing
hand harvesting of crops. As dairy herd size increased,
farmers needed bigger spreaders to handle the manure.
More passes through the field with heavier equipment to
spread fertilizer and manure, prepare a seedbed, plant,
spray pesticides, and harvest created the potential for
significant amounts of soil compaction.
A new logic developed that most soil-related problems
could be dealt with by increasing external inputs.
This is a reactive way of dealing with soil issues—you
react after seeing a “problem” in the field. If a soil is deficient
in some nutrient, you buy a fertilizer and spread it
on the soil. If a soil doesn’t store enough rainfall, all you
need is irrigation. If a soil becomes too compacted and
water or roots can’t easily penetrate, you use an implement,
such as a subsoiler, to tear it open. If a plant disease
or insect infestation occurs, you apply a pesticide.

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Are low nutrient status; poor water-holding capacity;
soil compaction; susceptibility to erosion; and disease,
nematode, or insect damage really individual and
unrelated problems? Perhaps they are better viewed as
symptoms of a deeper, underlying problem. The ability
to tell the difference between what is the underlying
problem and what is only a symptom of a problem is
essential to deciding on the best course of action. For
example, if you are hitting your head against a wall and
you get a headache—is the problem the headache and
aspirin the best remedy? Clearly, the real problem is
your behavior, not the headache, and the best solution is
to stop banging your head against the wall!

What many people think are
individual problems may just be symptoms of a
degraded, poor-quality soil

What many people think are individual problems
may just be symptoms of a degraded, poor-quality soil.
These symptoms are usually directly related to depletion
of soil organic matter, lack of a thriving and diverse
population of soil organisms, and compaction caused
by use of heavy field equipment. Farmers have been
encouraged to react to individual symptoms instead of
focusing their attention on general soil health management.
A new approach is needed to help develop farming
practices that take advantage of the inherent strengths
of natural systems. In this way, we can prevent the many
symptoms of unhealthy soils from developing, instead
of reacting after they develop. If we are to work together
with nature, instead of attempting to overwhelm and
dominate it, the buildup and maintenance of good levels
of organic matter in our soils are as critical as management
of physical conditions, pH, and nutrient levels.
A skeptic might argue that the challenges described
above are simply the result of basic economic forces,
including the long-run inexpensive cost of fossil fuel and
crop inputs (although this is changing), and the fact that
environmental consequences and long-term impacts are
not internalized into the economic equation. It could
then be argued that matters will not improve unless the
economic incentives are changed. We argue that those
economic motivations are already present, that sustainable
soil management is profitable, and that such management
will cause profitability to increase with greater
scarcity of resources and higher prices of crop inputs.
This book has four parts. Part 1 provides background
information about soil health and organic matter: what it
is, why it is so important, the importance of soil organisms,
and why some soils are of higher quality than others.
Part 2 includes discussions of soil physical properties, soil
water storage, and nutrient cycles and flows. Part 3 deals
with the ecological principles behind—and practices that
promote—building healthy soil. It begins with chapters
that place a lot of emphasis on promoting organic matter
buildup and maintenance. Following practices that build
and maintain organic matter may be the key to soil fertility
and may help solve many problems. Practices for enhancing
soil quality include the use of animal manures and
cover crops; good residue management; appropriate selection
of rotation crops; use of composts; reduced tillage;
minimizing soil compaction and enhancing aeration; better
nutrient and amendment management; good irrigation
and drainage; and adopting specific conservation practices
for erosion control. Part 4 discusses how you can evaluate
soil health and combine soil-building management strategies
that actually work on the farm, and how to tell whether
the health of your soils is improving.
SOURCES
Hills, J.L., C.H. Jones, and C. Cutler. 1908. Soil deterioration and
soil humus. In Vermont Agricultural Experiment Station Bulletin
135, pp. 142–177. Burlington: University of Vermont, College
of Agriculture.
Montgomery, D. 2007. Dirt: The Erosion of Civilizations. Berkeley:
University of California Press.
Tegmeier, E.M., and M.D. Duffy. 2004. External costs of agricultural
production in the United States. International Journal of
Agricultural Sustainability 2: 1–20.

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Building Soils for Better Crops, part1

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

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Building Soils for Better Crops, p3

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Building Soils for Better Crops, 3rd Edition
Sustainable Agriculture Research and Education (SARE).

——————————

Chapter 1
All over the country [some soils are] worn out, depleted, exhausted, almost dead.
But here is comfort: These soils possess possibilities and may be restored to high
productive power, provided you do a few simple things.
—C.W. BUR KETT , 1907
It should come as no surprise that many cultures
have considered soil central to their lives. After all,
people were aware that the food they ate grew from
the soil. Our ancestors who first practiced agriculture
must have been amazed to see life reborn each year
when seeds placed in the ground germinated and then
grew to maturity. In the Hebrew Bible, the name given
to the first man, Adam, is the masculine version of the
word “earth” or “soil” (adama). The name for the first
woman, Eve (or Hava in Hebrew), comes from the word
for “living.” Soil and human life were considered to be
intertwined. A particular reverence for the soil has been
an important part of the cultures of many civilizations,
including American Indian tribes.
Although we focus on the critical role soils play
in growing crops, it’s important to keep in mind that
soils also serve other important purposes. Soils govern
whether rainfall runs off the field or enters the soil and
eventually helps recharge underground aquifers. When
a soil is denuded of vegetation and starts to degrade,
excessive runoff and flooding are more common. Soils
also absorb, release, and transform many different chemical
compounds. For example, they help to purify wastes
flowing from the septic system fields in your back yard.
Soils also provide habitats for a diverse group of organisms,
many of which are very important—such as those
bacteria that produce antibiotics. Soil organic matter
stores a huge amount of atmospheric carbon. Carbon, in
the form of carbon dioxide, is a greenhouse gas associated
with global warming. So by increasing soil organic matter,
more carbon can be stored in soils, reducing the global
warming potential. We also use soils as a foundation for
roads, industry, and our communities.
WHAT KIND OF SOIL DO YOU WANT?
Soil consists of four important parts: mineral solids,
water, air, and organic matter. Mineral solids are sand,
silt, and clay and mainly consist of silicon, oxygen, aluminum,
potassium, calcium, and magnesium. The soil
water, also called the soil solution, contains dissolved
Healthy Soils

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