Abstract:
First and foremost, I would like to thank Professor Nigussie Dechassa (PhD) (chairperson of the
advisory committee), for his well-articulated professional guidance, constructive criticisms,
hospitality and for all kinds of support he provided me starting from the problem identification up
to the completion of the work. In addition, his meticulous review of the manuscripts was pivotal
in enhancing the quality of the dissertation and its presentation. I also extend my gratitude to the
other members of the advisory committee Dr. Yibekal Alemayehu, Prof. Tamado Tana and Dr.
Bobe Bedadi for their encouragement and the critical reviews they made on the manuscripts that
make up this dissertation.
I would like to thank the World Bank-supported Africa Center of Excellence for Climate Smart
Agriculture and Biodiversity Conservation hosted by Haramaya University for funding the
research work. My gratitude also goes to Haramaya University for providing me with the
equipment I required for drip irrigation. My appreciation goes also to Wolaita Sodo University for
granting me a leave of absence with pay to pursue my study. I also thank agricultural experts of
the East and West Hararghe Zones as well as the smallholder potato farmers whom I interviewed
for their enthusiastic cooperation during the survey study. I solemnly acknowledge Lemide and
other field technical assistants working at Haramaya University’s main campus research site for
mobilizing the necessary resources to undertake the field experiments. I would also like to extend
my sincere gratitude to all technical assistants of the soil and horticulture laboratories of Haramaya
University especially, Dilnesa, Lemi, Bane, Dheresa, Shewa, Fuad, and Yonas
My wife, Helen Teshome, is a special person to me, my success means nothing without her in my
life. I could not have succeeded in passing through the toughest phase of my life at Haramaya
University without her support, encouragement, and prayers. I am also very thankful to my cute
children Mihiret and Robel for their love and support. I would like to thank my friends Mesfin
Tebeje, Firew Sisay, and Dr. Fikrey Tesfaye for providing me with multidirectional supports
during the study period. I express my heartfelt gratitude to my family members for their endless
encouragement and moral support during the whole period of the study. Above all, I would like to
praise and glorify the Almighty God for He made all things possible to finish my study
