Front Matter.indd - Soil and Water Conservation Society

© SWCS. For Individual Use Only.

Environmental 

Benefits 

of Conservation 

on Cropland 

The Status of 

Our Knowledge 


Environmental 

Benefits 

of Conservation 

on Cropland 

The Status of 

Our Knowledge 

Max Schnepf and Craig Cox, Editors 

Soil and Water Conservation Society 

Ankeny, Iowa 


Copyright @ 2006 by the Soil and Water Conservation Society 

All rights reserved 

Manufactured in the United States of America 

Library of Congress Cataloging-in-Publication Data 

Environmental benefits of conservation practices on cropland : 

the status of our knowledge / Max Schnepf and Craig Cox, editors. 

p. cm. 

Includes bibliographical references and index. 

ISBN-13: 978-0-9769432-3-5 

ISBN-10: 0-9769432-3-9 

1. Agricultural conservation--United States. 2. Agriculture and state--United States. 3. Agricultural landscape 

management--United States. 4. Environmentalism--United States. I. Schnepf, Max, 1941- II. Cox, Craig A. (Craig Alan) 

S604.6.E58 2007 

630.973--dc22 

2007002199 

All photos are from the Photo Gallery, Natural Resources Conservation Service, U.S. Department of Agriculture. 


CONTENTS 

vi Contributors 

vii Foreword 

Craig Cox 

ix Preface 

Max Schnepf 

1 

1 Soil management practices 

Randall Reeder and Dale Westermann 

2 

89 Water management practices, rain-fed cropland 

J.L. Baker, M.J. Helmers, and J.M. Laflen 

3 

131 Water management practices, irrigated cropland 

Dean E. Eisenhauer, David Bjorneberg, and Dale Westermann 

4 

149 Nutrient management practices 

Andrew N. Sharpley, John P. Schmidt, and Gary W. Hergert 

5 

195 Pest management practices, pesticide mitigation 

R. Don Wauchope 

6 

243 Pest management practices, integrated pest management 

H. Michael Linker 

7 

269 Landscape management practices 

R. Lowrance, T.M. Isenhart, W.J. Gburek, F.D. Shields, Jr., 

P.J. Wigington, Jr., and S.M. Dabney 

318 Index 


AUTHORS 

J.L. Baker 

Professor, Department of 

Agricultural and Biosystems 

Engineering, Iowa State 

University, Ames 

David Bjorneberg 

Agricultural Engineer, 

Northwest Irrigation and 

Soil Research Laboratory, 

Agricultural Research 

Service, U.S. Department of 

Agriculture, Kimberly, Idaho 

S.M. Dabney 

Research Agronomist, 

National Sedimentation 

Laboratory, Agricultural 

Research Service, U.S. 

Department of Agriculture, 

Oxford, Mississippi 

Dean E. Eisenhauer 



Engineering, University of 

Nebraska, Lincoln 

W.J. Gburek 

Hydrologist, Pasture 

Systems and Watershed 

Management Research 

Unit, Agricultural Research 

Service, U.S. Department 

of Agriculture, University 

Park, Pennsylvania 

M.J. Helmers 

Assistant Professor, Department 

of Agricultural and 

Biosystems Engineering, 

Iowa State University, Ames 

Gary W. Hergert 

Professor, Agronomy-Horticulture, 

Panhandle Research 

& Extension Center, University 

of Nebraska, Scottsbluff. 

T.M. Isenhart 

Associate Professor, Department 

of Natural Resources 

Ecology and Management, 


J.M. Laflen 



Engineering, Iowa State 

University, Ames 

H. Michael Linker 

Integrated Pest Management 

Coordinator, College of Agriculture 

and Life Sciences, 

and Professor, Crop Science 

and Entomology, North 

Carolina State University, 

Raleigh 

Richard Lowrance 

Ecologist, Southeast 

Watershed Research Unit, 



Agriculture, Tifton, Georgia 

Randall Reeder 

Associate Professor, Department 

of Food, Agricultural 

and Biological Engineering, 

Ohio State University, 

Columbus 

Andrew N. Sharpley 

Soil Scientist, Pasture 






Park, Pennsylvania; now 

with Crop, Soil and Environmental 

Sciences, University 

of Arkansas, Fayetteville. 

John P. Schmidt 

Soil Scientist, Pasture 






Park, Pennsylvania 

F.D. Shields, Jr. 

Research Hydraulic Engineer, 

National Sedimentation 




Oxford, Mississippi 

R. Don Wauchope 

Research Chemist and 

Collaborator, Southeast 

Watershed Research Unit, 



Agriculture, Tifton, Georgia 

Dale Westermann 

Soil Scientist, Northwest 

Irrigation and Soil Research 




Kimberly, Idaho 

P.J. Wigington, Jr. 

Research Hydologist, U.S. 

Environmental Protection 

Agency, Corvallis, Oregon 

REVIEWERS 

Soil management 

Seth Dabney 



Agriculture, Oxford, Mississippi 

Gyles Randall 

Department of Soil, Water, 

and Climate, University of 

Minnesota, Waseca 

Cathy Sebold 

Natural Resources Conservation 

Service, U.S. 


Lincoln, Nebraska 

Bruce Wight 


Service, U.S. 


Lincoln, Nebraska 

Water management 

Jerry Bernard 


Service, U.S. 


Washington, D.C. 

Mike Burkart 



Agriculture, Ames, Iowa 

Brook Harker 

Agriculture and Agri-Food 

Canada, Regina, Saskatchewan 

Eilenn Kladivko 

Department of Agronomy, 

Purdue University, West 

Lafayette, Indiana 

Jerry Lemunyon 



of Agriculture, Fort 

Worth, Texas 

Nurient 

management 

Dennis Francis 



of Agriculture, Lincoln, 

Nebraska 

Bill Kuenstler 



of Agriculture, Fort 

Worth, Texas 

Antonio Mallarino 

Department of Agronomy 


Dwayne Westfall 

Soil and Crop Sciences 

Department, Colorado State 

University, Fort Collins 

Pest management 

David Eckhardt 

U.S. Geological Survey, 

Ithaca, New York 

Cathleen Hapeman 



of Agriculture, Beltsville, 

Maryland 

Landscape 

management 

Tom Drewes 


Service, U.S. 


Beltsville, Maryland 

Peter Groffman 

Institute of Ecosystem Studies, 

Millbrook, New York 

Lyn Townsend 


Service, U.S. 


Portland, Oregon 

Mark Weltz 



of Agriculture, Beltsville, 

Maryland 

© SWCS. For Individual Use Only. 

vi

FOREWORD 

This book is a product of two important changes 

in U.S. agricultural conservation policy: (1) the 

advent of the environmental movement and (2) 

major increases in funding for U.S. Department 

of Agriculture (USDA) conservation programs. 

For decades, the primary purpose of agricultural 

conservation programs was to improve the 

productivity of U.S. farms and ranches and to 

protect the “natural resource base” that sustained 

the agricultural enterprise. In the past 15 

years the environmental agenda—water quality, 

air quality, biodiversity, among other objectives—has 

superseded traditional objectives as 

the primary purposes of agricultural conservation 

programs. This change in goals, in my view, is 

the most important development in U.S. agricultural 

conservation programs since their inception 

in the 1930s. 

This change in purpose has been accompanied 

by a very large increase in funding for 

U.S. Department of Agriculture conservation 

programs and a new emphasis on improving the 

environmental management of working farms and 

ranches. Departmental conservation programs now 

account for expenditures of more than $4.5 billion 

a year, nearly double what was spent annually 

for those programs prior to the 2002 farm bill. 

Demands to document what taxpayers’ are getting 

for their investment in conservation have increased 

hand-in-hand with the increase in funding. 

These two policy changes create an urgent 

need to retool conservation practices, programs, 

and policy to meet the environmental challenge 

and to improve our ability to quantify, or at least 

simulate, the effect conservation practices and 

programs are having on environmental outcomes. 

Both of these needs can only be met by retooling 

and building our science base to inform environmental 

management in agricultural landscapes. 

This book is intended to be a first step toward 

retooling and building that science base by documenting 

what we know and what we don’t know 

about the effect current conservation practices 

applied to cropland have on the environment. Our 

goal was to consolidate current scientific knowledge 

to (1) immediately enhance the effectiveness 

of conservation programs and (2) make strategic 

decisions about strengthening our science base in 

the future. 

Our task proved more difficult than anticipated, 

but also more rewarding. After reading 

these chapters, I am left with a greater sense 

of optimism that we can achieve our ultimate 

objective—enhancing productivity, sustaining our 

resource base, and improving the environment 

simultaneously. 

Clearly, we know much more than we are using 

on a day-to-day basis to improve environmental 

quality in agricultural landscapes. We could 

increase immediately the effectiveness of our 

efforts by wider and sustained application of the 

knowledge of practice effects and interactions 

contained between the covers of this book. A 

more intensive effort to translate science into 

practice would pay large dividends for taxpayers, 

agriculture, and the environment. The benefit, for 

example, of more precise targeting of conservation 

practices emerges in these pages as perhaps 

the biggest short-term opportunity to increase the 

effectiveness of our efforts. Where conservation 

practices are placed on the landscape appears to 

be as important to determining environmental 

effects as which specific practices are applied. 

Translating what we currently know into more 

effective tools for targeting effort and investing 

more in research and development to produce and 

deploy more effective tools should, I think, be a 

high priority for policymakers, research leaders, 

and program managers. 

Finally, it is clear that we have in hand conservation 

practices and systems that, if applied 

effectively, produce real and meaningful environmental 

benefits. Those practices and systems are 

the “low-hanging fruit” that, if harvested, would 

accelerate production of the environmental benefits 

agriculture needs and taxpayers want. 

There are many more reasons for optimism 

contained in this book—too many to list here. 

But there also is ample evidence of the magnitude 

of the challenge we face and the imperative 

of making strategic investments now to improve 

our ability to meet that challenge. I hope this 

book helps to improve conservation science, 

practice, programs, and policies. Most importantly, 

I hope this book is just the beginning—a 

helpful contribution to a strategic, coordinated, 

and effective effort to meet the environmental 

challenge confronting our nation’s agriculture. 

— Craig Cox 

This book 

is intended 

to be a first 

step toward 

retooling and 

building that 

science base 

by documenting 

what 

we know 

and what we 

don’t know 

about the 

effect current 

conservation 

practices 

applied to 

cropland 

have on the 

environment. 


vii

PREFACE 

In 2004, as an adjunct to the Conservation Effects 

Assessment Project (CEAP), U.S. Department 

of Agriculture officials asked the staff of the 

Soil and Water Conservation Society to undertake 

a comprehensive literature review as a means of 

documenting the environmental effects of incorporating 

conservation practices into agricultural 

operations. The prime objective of this effort 

was to construct a scientific foundation for the 

CEAP initiative by documenting what we know 

and don’t know about the environmental effects 

of putting conservation practices on the land. 

Through CEAP, departmental officials hope to 

quantify the environmental benefits of conservation 

efforts more rigorously than in the past. 

The first phase of the work by Society staff was 

to focus on what effects conservation practices 

applied to cropland might have with regard to 

four environmental outcomes: water quality, soil 

quality, water conservation, and air quality. The 

Wildlife Society simultaneously undertook an 

assessment of cropland conservation practice 

effects on fish and wildlife habitat. Subsequent 

assessments were to look at practice effects on 

grazing land, wetlands, and other land uses. 

A decision was made to divide the assessent 

into five basic conservation systems—soil management, 

water management, nutrient management, 

pest management, and landscape management—then 

subdivide each of those conservation 

systems into two basic cropping systems—rainfed 

cropland and irrigated cropland. 

A lead author was then selected for each chapter—based 

on the demonstrated capability and 

expertise of that individual to deal with the assigned 

subject matter. Each lead author was given 

the discretion to recruit co-authors. 

Authors were asked to undertake a comprehensive 

literature search and summarize, in an 

integrated fashion, what is know and not known 

about the following five elements: 

• Positive and/or negative environmental 

effects on water quality, soil quality, water 

conservation, and air quality, in that order. 

• Interactions and potential tradeoffs among 

conservation practices, systems, and environmental 

outcomes. 

• Key factors driving the magnitude and direction 

of environmental effects, interactions, and 

tradeoffs. 

• The degree of confidence that could be accorded 

the documented environmental effects. 

• Critical gaps in knowledge that called for 

additional research. 

To achieve some consistency among chapters, 

authors were given a standardized outline to follow. 

A workshop, held in January 2005 to review and 

critique initial drafts of chapters, involved authors 

and peer reviewers (who also reviewed subsequent 

manuscript drafts). At that workshop, participants 

opted to forego the rain-fed versus irrigated 

cropping system division except in the case of the 

chapters on water management practices. Their 

rationale was simply that too much duplication 

would be introduced into the various chapters if 

the division were retained. A later decision to split 

the pest management practices chapter into two 

chapters—pesticide mitigation and integrated pest 

management—was based on unrelated factors, 

including a change in authors. 

Workshop participants also agreed on a “division 

of labor” among the chapters with respect 

to the conservation practices covered (see list on 

page x). All conservation practices commonly 

applied to cropland and for which the Natural 

Resources Conservation Service had established 

a national standard were divided among the 

five subject areas—soil management practices, 

water management practices, nutrient management 

practices, pest management practices, and 

landscape management practices. A few practices 

were placed in multiple chapters because authors 

felt compelled to cover those practices to achieve 

the degree of comprehensiveness requested. 

Authors also were allowed to add to the list 

practices for which no national standard exists to 

accommodate innovation and new technologies. 

The project proved to be a real challenge for 

authors, reviewers, and editors. Literature searches 

proved especially difficult, in part because of 

the volume of published information available on 

certain conservation practices and in part because 

of the lack of published research on other practices. 

Also difficult was the location of so-called 

“gray” literature—those extension bulletins, technical 

notes, and other materials regularly issued 

by agencies and academic institutions. In the end, 

much of that material was ignored. 

So, for what it is worth, here is the final product 

of this ambitious undertaking. Shortcomings 

likely are obvious. At the same time, project 

participants pulled together an enormous amount 

of material relating to the environmental effects 

of putting conservation practices on cropland, 

material that should prove useful to conservation 

policymakers and practitioners alike. 

Society staff members thank the authors and 

reviewers for their significant contributions to 

this effort. Thanks also are due officials of the 

U.S. Department of Agriculture’s Agricultural 

Research Service and Natural Resources Conservation 

Service who supported the effort financially 

and otherwise. 

— Max Schnepf 


ix

CROPLAND CONSERVATION PRACTICES 

During a workshop held as part of this literature review project, authors and peer reviewers created a list of all cropland-oriented conservation 

practices for which Natural Resources Conservation Service personnel had set national standards. Those practices were then divided among the 

five general topics dealt with in this book. A handful of additional conservation practices or activities for which no national standards exist were 

then added to the list, which follows. Generally, authors attempted to avoid duplicate coverage of a specific practice from one chapter to another, 

but that was not always possible. 

Soil management practices 

Alley cropping 311 

Conservation cover 327 

Conservation crop rotation 328 

Contour buffer strip 332 

Contour farming 330 

Contour orchard 331 

Cover crop 340 

Critical area planting 342 

Cross-wind ridges 

589A 

Cross-wind trap strips 

589C 

Deep tillage 324 

Field border 386 

Herbaceous wind barrier 603 

Mulching 484 

PAM 450 

Residue management, mulch till 

329B 

Residue management, no till/strip till 

329A 

Residue management, ridge till 

329C 

Residue management, seasonal 344 

Salinity and sodic soil management 610 

Stripcropping 585 

Surface roughening 609 

Tree/shrub establishment 612 

Vegetative barrier 601 

Windbreak/shelterbelt establishment 380 

Windbreak/shelterbelt renovation 650 

Water management practices 

Ditch vegetation 

Diversion 362 

Drainage water management 554 

Filter strip 393 

Grade stabilization structure 410 

Grassed waterway 412 

Hillside ditch 423 

Irrigation canal/lateral 320 

Irrigation ditch/canal lining, plain concrete 

428A 

Irrigation ditch/canal lining, flexible membrane 

428B 

Irrigation ditch/canal lining, galvanized steel 

428C 

Irrigation field ditch 388 

Irrigation land leveling 464 

Irrigation regulating reservoir 552 

Irrigation storage reservoir 436 

Irrigation system, microirrigation 441 

Irrigation system, sprinkler 442 

Irrigation system, surface/subsurface 443 

Irrigation system, tailwater recovery 447 

Irrigation pipeline, aluminum tubing 

430AA 

Irrigation pipeline, asbestos-cement 

430BB 

Irrigation pipeline, nonreinforced concrete 

430CC 

Irrigation pipeline, high-pressure, 

underground, plastic 

430DD 

Irrigation pipeline, low-pressure, 

underground, plastic 

430EE 

Irrigation pipeline, steel 

430FF 

Irrigation pipeline, reinforced plastic mortar 

430GG 

Irrigation pipeline, rigid gated pipeline 

430HH 

Irrigation water management 449 

Mole drain 482 

Open channel 582 

Precision land forming 462 

Pumping plant 533 

Riparian forest buffer 391 

Riparian herbaceous cover 390 

Rock barrier 555 

Row arrangement 557 

Structure for water control 587 

Subsurface drainage 606 

Surface drainage, field ditch 607 

Surface drainage, main/lateral 608 

Terrace 600 

Tile line drainage innovations 

Underground outlet 620 

Vertical drain 630 

Water and sediment control basin 638 

Waterspreading 640 

Water well 642 

Well decommissioning 351 

Nutrient management practices 

Anaerobic digester, ambient temperature 365 

Anaerobic digester, controlled temperature 366 

Atmospheric resources quality management 370 


Composting facility 317 


Feed management 592 

Manure transfer 634 

Nutrient management 590 

Roof-runoff structure 558 

Waste treatment lagoon 359 

Waste storage 313 

Waste utilization 633 

Wastewater treatment strip 635 

Well-water testing 355 

Pest management practices 

Atmospheric resources 

quality management 370 

Conservation cover 327 



Mulching 484 

Pest management 595 

Landscape management practices 

Corridor connectivity 

Channel bank vegetation 322 

Channel stabilization 584 

Dam 402 

Early succession habitat 

development/management 647 

Green-tree reservoir 

Impoundment 

Perennial vegetation re-establishment 

Pond 378 

Restoration/management of 

declining habitats 643 

Riparian forest buffer 391 

Riparian herbaceous cover 390 

Stream habitat 

improvement/management 395 

Streambank-shoreline protection 580 

Structure for water control 587 

Upland wildlife habitat management 645 

Water and sediment basin 638 

Wetland creation 658 

Wetland enhancement 659 

Wetland restoration 657 

Wetland wildlife habitat improvement 644 

Windbreak/shelterbelt establishment 380 


x

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