Handbook of Soils for Landscape Architects

283 Pages·2000·14.4 MB·English

by  Robert F. Keefer

Handbook of Soils for
Landscape Architects
This page intentionally left blank
Handbook of Soils for
Landscape Architects
ROBERT F. KEEFER
OXFORD
UNIVBRSITY PRESS
2000
OXPORD
UNIVERSITY PRESS
Oxford New York
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Copyright © 2000 by Oxford University Press, Inc.
Published by Oxford University Press, Inc.
198 Madison Avenue, New York, New York 10016
Oxford is a registered trademark of Oxford University Press
All rights reserved. No part of this publication may be produced,
stored in a retrieval system, or transmitted, in any form or by any means,
electronic, mechanical photocopying, recording, or otherwise,
without the prior permission of Oxford University Press.
Library of Congress Cataloging-in-Publication Data
Keefer, Robert F.
Handbook of soils for landscape architects / by Robert F. Keefer.
p. cm.
Includes bibliographical references and index.
ISBN 0-19-512102-3
1. Soil science. 2. Landscape architecture. I. Title.
S591.K385 2000
631.4—dc21 98-29581
9 8 7 6 5 4 3 21
Printed in the United States of America
on acid-free paper
Preface
Landscape Architecture curriculum at colleges and universities
often requires a course in soils. During my teaching in the Col-
lege of Agriculture and Forestry at West Virginia University, I
was requested to teach a course specifically for Landscape Ar-
chitects. The faculty and students were concerned that the gen-
eral course in soils at WVU was not providing them with their
needs. After gathering the information required to teach this
course, it occurred to me that students in Landscape Architec-
ture throughout the country could use a simplified handbook of
soils information written specifically for them. The students and
faculty were pleased with the course, and when I asked them if
a text for such a course would he accepted, they thought it would.
The number of students who could use such a book was calcu-
lated to be from 1200 to 1500 annually. Therefore, I undertook
the task of writing and illustrating this book.
Sincere thanks are extended to the West Virginia University
landscape architecture professor, Mr. George Longenecker, for
his suggestions, encouragement, and for providing names of sev-
eral reviewers. My son, Brian Douglas Keefer, graduated with a
B.S.L.A. degree in landscape architecture from West Virginia
University in 1988; presently, he is involved in land planning
for golf course development and design of golf courses in many
places throughout the world. He was generous in giving some
of his time to redraw by hand many of the graphics so they would
be acceptable to the intended readers. Helping him in this en-
deavor were two of his friends, Jennifer Oliviera and Russell
Oliviera. Jennifer Oliviera graduated in 1998 with honors from
the Landscape Architecture Program, California Polytechnic
State University, San Luis Obispo, California. Russell Oliviera,
vi Preface
her husband, has a natural ability for drawing cartoons and a
witty sense of humor that added interest to the figures. Brian also
provided me with names of several reviewers. Lastly, I want to
thank my wife for her patience and encouragement during the
writing and editing of the manuscript.
R.F.K.
Contents
1: Use of Soil Surveys for Landscape Architecture 3
Modern Soil Survey Reports 3
2: Basic Information About Soils and Plants 9
Plant Requirements for Growth 9
What Is Soil? 9
3: Parts of a Soil (Soil Constituents)—Air, Water,
Minerals, and Organic Matter 21
Physical Parts of a Soil 21
Chemical Parts of a Soil 22
Biological Parts of a Soil 22
4: Physical Properties of Soils 27
Soil Texture 27
Soil Structure 30
Soil Bulk Density 32
Soil Depth 32
Soil Aeration 35
Soil Water 40
5: Movement of Water Across Soils (Erosion) 53
Erosion Defined 53
Types of Water Erosion 53
Types of Accelerated Erosion 54
Factors That Determine Extent of Erosion 57
6: Nature of Soil Erodibility 61
Soil Texture 61
Soil Structure 62
viii Contents
Soil Organic Matter 64
Soil Permeability 65
Use of a Nomograph to Evaluate Soil
Erodibility Using the Four Factors Above 65
7: Controlling Erosion 69
Improving Soil Structure 69
Covering Soil With Plants 72
Covering Soil With Mulch 72
Using Special Structures 78
8: Effective Water Use—Irrigation 83
Which Soils Are Suitable for Irrigation? 83
When Should Water Be Applied? 83
How Much Water to Add? 85
Kinds of Irrigation Systems 86
9: Chemical Properties of Soils for Growing Plants 91
Soil Reaction (pH) 91
Factors That Cause Acids to Form in Soils 96
Correcting Soil Acidity 99
Base-Forming Factors 101
Correcting Alkalinity in Arid Regions 103
10: Soil Nutrients (Soil Fertility) 107
Respiration vs. Photosynthesis 107
Elements Required by Plants (Essential Nutrients) 107
11: Macronutrients—Nitrogen 113
Nitrogen in Plants 113
Nitrogen in Soils 117
Transformations of Nitrogen in Soils 118
Decomposition (Mineralization) Processes 118
Nitrification = Formation of Nitrates 119
Nitrogen Fixation in Soils 122
Nitrogen Added to Soils From the Atmosphere 125
Losses of Nitrogen from Soils 125
12: Macronutrients—Phosphorus and Potassium 131
Phosphorus in Plants 131
Phosphorus in Soils 133
Contents ix
Factors Affecting Availability of Phosphorus in Soils 135
Practical Control of Phosphorus Availability 139
Potassium in Plants 140
Potassium in Soils 141
13: Macronutrients—Calcium, Magnesium, and Sulfur 147
Calcium and Magnesium in Soil Is Related to Liming 147
Amount of Limestone to Apply 148
Kinds of Lime 149
Neutralizing Power of Liming Materials 150
Fineness of a Limestone 150
When and How to Apply Lime 151
Soil Calcium and Magnesium Per Se 152
Plant Calcium and Magnesium 153
Sulfur in Plants 154
Sulfur in Soils 155
14: Micronutrients 157
Forms of Micronutrients Present in Soils 157
Factors Affecting Availability of Micronutrients 161
Anions—Boron, Chlorine, and Molybdenum 164
Soil Management and Micronutrient Needs 166
15: Fertilizers 169
Nitrogen Fertilizers 169
Phosphorus Fertilizers 173
Potassium Fertilizers 174
Sulfur Fertilizers 175
Micronutrient Fertilizers 175
Mixed Fertilizers 175
Farmyard Manures 176
Methods of Fertilizer Application 177
Movement of Fertilizers in Soils 179
16: Soil Organic Matter 183
Importance of Soil Organic Matter 183
Definition of Soil Organic Matter 183
Composition of Soil Organic Matter 183
Soil Changes When Organic Matter Is Added 184
Decomposition of Soil Organic Matter 186
Sources of Organic Matter 188