FACULTY OF AGRICULTURAL SCIENCES Institute of Plan Production and Agroecology in the ...

173 Pages·2010·2.84 MB·English

FACULTY OF AGRICULTURAL SCIENCES
Institute of Plan Production and Agroecology in the Tropics and Subtropics
University of Hohenheim
Field: Plant Production
Prof. Dr. Georg Cadisch

NUTRIENT MANAGEMENT AND SPATIAL VARIABILITY OF SOILS ACROSS
SCALES AND SETTLEMENT SCHEMES IN ZIMBABWE

Dissertation
Submitted in fulfillment of the requirements for the degree
“Doktor der Agrarwissenschaften”
(Dr.sc.agr. / Ph.D. in Agricultural Sciences)

to the
Faculty of Agricultural Sciences

Presented by
Juan Guillermo Cobo Borrero
Cali, Colombia
2010
This thesis was accepted as a doctoral dissertation in fulfillment of the requirements for the
degree “Doktor der Agrarwissenschaften” (Dr.sc.agr. / Ph.D. in Agricultural Sciences) by the
faculty Agricultural Sciences of the University of Hohenheim on 15.04.2010.

Date of oral examination: 08.06.2010

Examination Committee

Supervisor and Reviewer Prof. Dr. Georg Cadisch

Co-Reviewer Prof. Dr. Torsten Müller

Additional Examiner Prof. Dr. Hans Piepho

Dean of Studies and Head of the Committee Prof. Dr. Andreas Fangmeier
Dedicated to the memory of my beloved father

ACKNOWLEDGEMENTS

Doing a Ph.D. is a long ride, full of ‘ups and downs’. Therefore, it would be very boring to do
that journey alone and, in fact, simply impossible. Thus many people contributed to the
realization of this thesis.

Firstly, I would like to express my immense gratitude and appreciation to my professor, Dr.
Georg Cadisch, for accepted me as part of his research team, and for all the guidance and
support during the whole phase of my doctorate. I learned a lot from him; not only in front of
a spectrometer, interpreting data from a graph, or being critical to a paper. Thus, working
with Prof. Cadisch was a constructive experience, a pleasure and, moreover, an honor.

My sincere recognition also goes to Dr. Gerd Dercon, my direct supervisor. His incredible
ideas and constructive criticism made this thesis a reality. I have never met somebody so
passionate with his work, with rejecting or accepting an experimental hypothesis, or by
teaching about a geochemical process. I hope I could absorb something from that passion.
Prof. Dr. Thorsten Muller, Prof. Dr. Thomas Berger and Prof. Dr. Hans Piepho are also
acknowledged for their willingness on being part of my thesis committee and defense.

Without the initial support of Dr. Robert Delve this thesis would not exist. He encourages me
with pursuing my doctorate and received me within his group in TSBF-CIAT, Zimbabwe.
Moreover, he provided with the necessary funding during the 1st year of my PhD program
and financed the field data collection phase. Thus, I’m grateful to him for that. I also want to
express my thanks to Dr. Idupulapati Rao, Dr. Edmundo Barrios and the ‘Fondo para el
Desarrollo del Recurso Humano (FDRH)’ of CIAT for their support while I was still part of
TSBF-CIAT Colombia, where I worked for seven years.

The Faculty of Agricultural Sciences from the University of Hohenheim is deeply
acknowledged for providing me with a scholarship during two years of my doctoral program.
Dr. Ludwig Kammesheidt and Mrs. Bärbel Sagi are also thanked for giving me the
opportunity to work for them at Tropenzentrum (TROZ) as a HiWi (scientific assistant) once
my scholarship finished. The TROZ web page (https://troz.uni-hohenheim.de) is one of the
results of this work.
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Many thanks are also given to Prof. Dr. Ken Giller and his team at the University of
Wageningen; Dr. Keith Shepherd, Dr. Tor Vågen and their colleagues at ICRAF, Nairobi,
and Dr. Andrew Farrow and Dr. Pascal Sanginga at CIAT, Kampala, for all the valuable
discussions that helped me to develop my ideas during the development of my proposal.
Discussing with them showed me a world full of challenges, but also full of possibilities.

In Zimbabwe very special thanks are given to all the farmers in the three villages for all their
knowledge, patience and enthusiasm on this project. Particularly to the Mudimu and Katsiga
families (Kanyera village), to Mr. Mukazika and Mr. Chirimuta (Chomutomora village), and
to the Chidamba, Chitate and Njilayasvova families (Hereford farm). Thanks are also given
to Mrs. Progress Kahari, Progress Masiiwa and their colleagues from the Department of
Agricultural Research and Extension of the Ministry of Agriculture of Zimbabwe (AREX).
They provide me with logistic support and valuable information in each region. My gratitude
also go to all AREX and DAPP (Development Aid from People to People) officers in the
three villages: Joseph Nengare and Joseph Chirume (Kanyera), Philip Ngirazi and Farirai
Mabhiza (Chomotumora), and Nelson Guwakuwa and Magret Mushonga (Hereford).
Without them, working in each community would be simply not possible.

Especial thanks go to Chengetai Kadzere, my field assistant and translator, for his valuable
help and company during field activities. He was my ‘right hand’ and my ‘ears’. I’m also
grateful to Dr. Justice Nyamangara and Dr. Amon Murwira from the University of Zimbabwe
for our successful collaboration which yielded two master and two bachelor theses. Thanks
are given to those students: Tsitsi Yekeye, Lazarus Chapungu, Patience Mahembe and
Trylord Gotosa for their patience with me and their expertise, from which I learnt a lot. My
gratitude also goes to the rest of the staff at the University of Zimbabwe, and to all people at
TSBF-CIAT Zimbabwe, at the International Maize and Wheat Improvement Center
(CIMMYT) in Harare, and at the University of Bindura, for fruitful discussions and logistic
support.

Being in Zimbabwe was a great experience, and things would be very different without the
company of several people. Especially, I want to express my gratitude to Ashleigh Appel,
Christian Thielfelder, Ruth Verhey, Dixon Chibanda and Lynda Stranix for their friendship
and the hand they always gave me in difficult moments.

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In Germany thanks are also given to to Dr. Thomas Hilger, Dr. Carsten Marhon and Dr.
Frank Rashe for valuable discussions we had during my time in Hohenheim. I’m especially
grateful to Dr. Marhon for the translation of the summary to German. Thanks also go to my
two other master students, Coral Monje and Mercy Rewe, since it was a pleasure to work
with them. My appreciation also goes to Regina Geissler and Gabriele Kircher for
administrative support, and to Stefan Becker, Cheryl Batistel, Irene Chukwumah and the staff
of Landesanstalt für Landwirtschaftliche Chemie in the University of Hohenheim for their
assistance during laboratory analyses. I also thank Prof. Dr. Hans Piepho for statistical
advice, and Dr. Joachim Ingwersen and Yohannes Ayanu for GIS advice. Thanks also go to
Bruker Optik, especially to Andrea Schmidt, for their useful help during the data analyses of
mid-infrared spectra.

My appreciation also goes to my past and present colleagues and friends at the University of
Hohenheim, with which I shared offices, papers, lunches, trips, laughs, tears, drinks, cakes
and even famous recipes: Dr. Mingrelia España, Dr. Wanwisa Punsak, Dr. Tee Tuan Pang,
Dr. Agustin Mercado, Petra schmitter, Michael Scott Demyan, Juan Carlos Laso, Betha
Lusiana, Teodardo Jose Calles, Aunnop Puttaso, Melvin Lippe, Irene Chukwumah, Beni
Ndambi, Hanne Slaets, Christian Brandt, Thanh Nguyen, Dr. Carolina Gonzalez, Dr. Ana
Treydte, Silke Will, Marija Anyusheva, German Calberto, Manuel Narjes, Juana Cordoba,
Nuria Rodriguez Lopez, Sara González, Lorena Piles Tortajada, Fabian Klotz, Lourdes
Hernandez, Gabriela Bermejo, Jorge Samaniego and Stefanie Colombo.

Thanks are also given to all my family and friends in Colombia and worldwide, whom with
their messages or calls showed me that despite the distance (in space and time) they were
always here. From them, my mother deserves a very special place, as her support and
unconditional love has been critical for me to continue moving forward. The memory of my
father has been also a vital part of this enterprise. He died one year before I started my
doctorate, but he has been always with me… and always will.

Last but not least, I would like to finish thanking my girlfriend, Olga Beletskaya. Without all
her constant support, love and patience, I would never be able to find the strength for
finishing this thesis.
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TABLE OF CONTENTS

ACKNOWLEDGEMENTS .................................................................................................... v
TABLE OF CONTENTS ....................................................................................................... ix
LIST OF ABBREVIATIONS ............................................................................................. xiii
CHAPTER 1 GENERAL INTRODUCTION ...................................................................... 1
1.1. Background ..................................................................................................................... 3
1.2. Zimbabwe ........................................................................................................................ 3
1.2.1. Natural regions, vegetation and soils ....................................................................... 3
1.2.2. Land reform and the emergence of settlement schemes ........................................... 5
1.2.3. Small-scale farming systems ..................................................................................... 6
1.2.4. Soil fertility management strategies ......................................................................... 7
1.3. Soil spatial variability at different scales ........................................................................ 8
1.4. Techniques used in this study .......................................................................................... 9
1.4.1. Nutrient balances .................................................................................................... 10
1.4.2. Participatory approaches ....................................................................................... 11
1.4.3. Infrared spectroscopy ............................................................................................. 12
1.4.4. Geostatistics ........................................................................................................... 13
1.5. Justification ................................................................................................................... 14
1.6. Hypotheses .................................................................................................................... 15
1.7. Goal and objectives ....................................................................................................... 16
1.8. Outline of the study ....................................................................................................... 16
CHAPTER 2 NUTRIENT BALANCES IN AFRICAN LAND USE SYSTEMS
ACROSS DIFFERENT SPATIAL SCALES: A REVIEW OF APPROACHES,
CHALLENGES AND PROGRESS...................................................................................... 17
2.1. Abstract ......................................................................................................................... 19
2.2. Key words ..................................................................................................................... 20
2.3. Introduction ................................................................................................................... 20
2.4. Data retrieval criteria and analyses ............................................................................... 22
2.5. Results and discussion ................................................................................................... 23
2.5.1. Nutrient balances in Africa..................................................................................... 23
2.5.2. Methodological approaches and limitations .......................................................... 27
2.5.3. Nutrient balances at different spatial scales .......................................................... 33
2.5.4. Scaling-up challenges ............................................................................................. 38
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2.5.5. Vanguard techniques for nutrient balance studies ................................................. 43
2.6. Conclusions and further recommendations ................................................................... 46
CHAPTER 3 CROPPING STRATEGIES, SOIL FERTILITY INVESTMENT AND
LAND MANAGEMENT PRACTICES BY SMALLHOLDER FARMERS IN
COMMUNAL AND RESETTLEMENT AREAS IN ZIMBABWE ................................. 51
3.1. Abstract ......................................................................................................................... 53
3.2. Key words ..................................................................................................................... 54
3.3. Introduction ................................................................................................................... 54
3.4. Materials and methods .................................................................................................. 56
3.4.1. Selection and description of research sites ............................................................ 56
3.4.2. Community meetings, group activities and surveys ................................................ 57
3.4.3. Detailed assessment of stratified selected farmers ................................................. 58
3.4.4. Soil and plant analysis ............................................................................................ 59
3.4.5. Calculations and statistical analyses ..................................................................... 59
3.5. Results ........................................................................................................................... 60
3.5.1. Cropping systems .................................................................................................... 60
3.5.2. Maize performance ................................................................................................. 61
3.5.3. Partial nutrient balances ........................................................................................ 63
3.5.4. Factors affecting maize productivity ...................................................................... 65
3.5.5. Soil management practices ..................................................................................... 66
3.5.6. Farmers’ perceptions of soil fertility and crop productivity changes with time .... 68
3.6. Discussion ..................................................................................................................... 69
3.6.1. Linking crop production, soil fertility investments and soil quality ....................... 69
3.6.2. Access to nutrient resources ................................................................................... 70
3.6.3. Linking investments in soil fertility and land conservation to farmers’ perceptions
.......................................................................................................................................... 71
3.6.4. Policy implications and future research needs ...................................................... 72
3.7. Conclusions ................................................................................................................... 73
CHAPTER 4 INTEGRATION OF MID-INFRARED SPECTROSCOPY AND
GEOSTATISTICS IN THE ASSESSMENT OF SOIL SPATIAL VARIABILITY AT
LANDSCAPE LEVEL .......................................................................................................... 75
4.1. Abstract ......................................................................................................................... 77
4.2. Key words ..................................................................................................................... 78
4.3. Introduction ................................................................................................................... 78
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