SOIL QUALITY IN ORGANIC CROPPING SYSTEMS

173 Pages·2016·1.29 MB·English

by  Clark, Kerry M.

SOIL QUALITY IN ORGANIC CROPPING SYSTEMS
________________________________________________________________________
A Dissertation Presented to
The Faculty of the Graduate School
At the University of Missouri
________________________________________________________________________
In Partial Fulfillment
Of the Requirements for the Degree
Doctor of Philosophy
_______________________________________________________________________
By
KERRY MAUREEN CLARK
Drs. Randall Miles and Robert Kremer, Dissertation Supervisors
MAY 2016
The undersigned, appointed by the Dean of the Graduate School,
Have examined the dissertation entitled
SOIL QUALITY IN ORGANIC CROPPING SYSTEMS
Presented by Kerry Maureen Clark
A candidate for the degree of
Doctor of Philosophy
And herby certify that, in their opinion, it is worthy of acceptance.

_______________________________________________________________
Randall J. Miles (Chair)

______________________________________________________________
Robert J. Kremer (Co-Chair)

______________________________________________________________
Stephen H. Anderson

______________________________________________________________
Kelly A. Nelson
DEDICATION
This work is dedicated to William and Dolores Clark
and
Pieter Los, Jill Staples, Kristen Veum, Jodie Reisner, Christi Cole and Kristin Bilyeu
ACKNOWLEDGEMENTS
I would like to thank Dr. David Sleper, my mentor and supervisor in the Soybean
Breeding Program for nearly twenty years. Dr. Sleper always encouraged further
education and not only gave me the opportunity to take soils classes while working for
him but he also paid for one semester of coursework. He always had the highest trust in
me and I have always had the greatest respect for him.
Dr. Randall Miles deserves thanks for getting me interested in soil science over 30
years ago and for being a mentor as I earned my soil morphologist license and then
conducted research in soil health. He allowed me to be assistant coach to the MU soil
judging team and turned the reins over to me for a successful showing by the team in
2013. I have taken every course Dr. Miles has taught at MU and have enjoyed each of
them. Dr. Robert Kremer opened my eyes to the incredible world of soil microorganisms
and has been an instrumental collaborator on grants that fund my research and the
Organic Program at MU. His patience and advice have been instrumental in my success.
Dr. Stephen Anderson and Dr. Kelly Nelson have served as valuable committee members
with sage advice and questions that encourage deeper analysis than I might otherwise
have considered.
I am deeply grateful to Jill Staples, my research assistant and Dara Boardman, my
fellow PhD student. Without Jill, I would not have completed this research. She is an
excellent scientist, lab manager, data collector and logistician. I would like to thank Dr.
Kristen Veum, who has assisted me with lab analysis, data analysis and general good
advice. I am very grateful to Donna Brandt and Russell Dresbach at the MU Soil Health
Assessment Center for their fast and fastidious assistance with my PLFA samples and
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also sharing lab protocols. I am also grateful to Jodie Reisner for her encouragement and
advice, Amanda Wolfgeher for taking soil samples in one of our worst drought seasons
ever, Debi Kelly for her collaboration on the organic project and Dr. Robert Myers for his
leadership in cover crop and soil health research at MU and throughout the Midwest.
More thanks to Christi Cole, who helped cover my work while I was in classes and to Dr.
Kristin Bilyeu, who opened up new opportunities for meaningful research.
Finally, my deepest gratitude goes to my parents, who have seen me very little
since I began my quest for a PhD. From them I learned to absorb as much information as
possible, work hard and dream big. I also thank my brother, Casey Clark, who helped me
wrap up my lab analysis in the final hours of this project.
This work was funded by the Ceres Trust and the USDA NIFA under cooperative
agreements 0032909 and 003211. Any opinions, findings, conclusions or
recommendations expressed in this dissertation are those of the author and do not
necessarily reflect the view of the U.S. Department of Agriculture or the Ceres Trust.

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TABLE OF CONTENTS
Acknowledgements………………………………………………………………………. ii
List of Tables………………………………………………………………...………..… ix
List of Figures………………………………………...……………….………………. xvii
CHAPTER ONE ................................................................................................................. 1
INTRODUCTION .............................................................................................................. 1
Bibliography .................................................................................................................... 8
CHAPTER TWO .............................................................................................................. 13
CORN, SOYBEAN AND WHEAT PRODUCTION ON A CLAYPAN SOIL USING
CONVENTIONAL ORGANIC AND ORGANIC NO-TILLAGE PRACTICES ........... 13
Abstract ......................................................................................................................... 13
Keywords: .................................................................................................................. 14
Abbreviations: ........................................................................................................... 14
Introduction ................................................................................................................... 15
Materials and Methods .................................................................................................. 18
Research Site and Design .......................................................................................... 18
Weather ...................................................................................................................... 19
Equipment modification ............................................................................................ 19
Crop Management ..................................................................................................... 20
Crop Data Collection ................................................................................................. 21
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Soil Data Collection................................................................................................... 22
Statistical Analysis .................................................................................................... 22
Results and Discussion .................................................................................................. 22
Cover Crop ................................................................................................................ 22
Corn Population and Yield ........................................................................................ 25
Soybean Population and Yield .................................................................................. 28
Wheat Yield ............................................................................................................... 29
Soil Organic Carbon .................................................................................................. 30
Conclusion ..................................................................................................................... 31
Acknowledgements ....................................................................................................... 33
Bibliography .................................................................................................................. 42
CHAPTER THREE .......................................................................................................... 47
SOIL QUALITY IN CONVENTIONAL TILLED AND NO-TILL ORGANIC
SYSTEMS......................................................................................................................... 47
Abstract ......................................................................................................................... 47
Keywords ................................................................................................................... 48
Abbreviations............................................................................................................. 48
Introduction ................................................................................................................... 49
Materials and Methods .................................................................................................. 52
Research Site and Design .......................................................................................... 52
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Weather ...................................................................................................................... 53
Crop Management ..................................................................................................... 54
Soil Analyses ............................................................................................................. 55
Statistical Analysis .................................................................................................... 57
Soil Management Assessment Framework................................................................ 58
Results and Discussion .................................................................................................. 58
Soil Physical Indicator ............................................................................................... 58
Soil Biological Indicators .......................................................................................... 60
Soil Carbon ................................................................................................................ 60
PLFA ......................................................................................................................... 62
β-Glucosidase ............................................................................................................ 66
Soil Chemical Indicators ........................................................................................... 67
SMAF Soil Quality Index .......................................................................................... 68
Conclusion ..................................................................................................................... 70
Acknowledgements ....................................................................................................... 70
Bibliography .................................................................................................................. 83
CHAPTER FOUR ............................................................................................................. 91
EFFECT OF CROP ROTATION ON SOIL QUALITY AND THE WEED SEEDBANK
DURING THE THREE YEAR TRANSITION TO CERTIFIED ORGANIC
PRODUCTION ................................................................................................................. 91
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Abstract ......................................................................................................................... 91
Keywords ................................................................................................................... 92
Abbreviations............................................................................................................. 92
Introduction ................................................................................................................... 93
Materials and Methods .................................................................................................. 98
Research Site and Design .......................................................................................... 98
Weather ...................................................................................................................... 98
Crop Management ..................................................................................................... 99
Plant Analyses ......................................................................................................... 100
Weed Analyses ........................................................................................................ 100
Soil Analyses ........................................................................................................... 101
Statistical Analysis .................................................................................................. 104
Results and Discussion ................................................................................................ 105
Yield ........................................................................................................................ 105
Weed Suppression ................................................................................................... 108
Soil Quality .............................................................................................................. 109
Conclusions ................................................................................................................. 113
Acknowledgements ..................................................................................................... 114
Bibliography ................................................................................................................ 128
CHAPTER FIVE ............................................................................................................ 134
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TIMING AND METHOD OF ORGANIC CORN PLANTING IN COVER CROPS .. 134
Abstract ....................................................................................................................... 134
Keywords ................................................................................................................. 135
Abbreviations........................................................................................................... 135
Introduction ................................................................................................................. 136
Materials and Methods ................................................................................................ 138
Research Site and Design ........................................................................................ 138
Crop Management ................................................................................................... 139
Data Collection ........................................................................................................ 140
Statistical Analysis .................................................................................................. 140
Results and Discussion ................................................................................................ 141
Conclusion ................................................................................................................... 144
Acknowledgements ..................................................................................................... 144
Bibliography ................................................................................................................ 146
CONCLUSIONS............................................................................................................. 149
VITA ............................................................................................................................... 152

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