Coping with drought for food security in Tigray, Ethiopia Araya Alemie Berhe Thesis committee Thesis supervisor Prof.dr.ir. L. Stroosnijder Professor in Land Degradation and Development Thesis co-supervisor Dr. S.D. Keesstra Lecturer at the Land Degradation and Development Group Other members Prof. dr. K.E. Giller, Wageningen University Prof. dr. D. Gabriels, Ghent University, Belgium Dr. G. Sterk, Utrecht University Dr. A. Bekele, ICRAF Nairobi, Kenya This research was conducted under the auspices of Graduate School: C.T. de Wit Production Ecology and Resource Conservation Coping with drought for food security in Tigray, Ethiopia Araya Alemie Berhe Thesis submitted in fulfilment of the requirements for the degree of doctor at Wageningen University by the authority of the Rector Magnificus Prof. dr. M.J. Kropff, in the presence of the Thesis Committee appointed by the Academic Board to be defended in public on Thursday 16 June 2011 at 11 a.m. in the Aula. Araya Alemie Berhe Coping with drought for food security in Tigray, Ethiopia, 172 pages. Thesis, Wageningen University, Wageningen, NL (2011) With references, with summaries in Dutch and English ISBN 978-90-8585-925-3 Also published as Tropical Resource Management Papers, No. 100 (2011); ISSN 0926-9495 Financially supported by Netherlands Fellowship Programme (NFP) Land Degradation & Development (LDD) Group of Wageningen University Acknowledgements First of all, I would like to thank God for His helps and blessings in my personal life. I am deeply grateful to the Netherlands Organization for Higher Education (NUFFIC) Netherlands for supporting my study and research. Without the Netherlands Fellowship Programme (NFP) it would not have been possible to present this work. I am also grateful to the Regional Universities Forum for capacity building in Agriculture (RUFORUM) for supporting part of my field works. I would like to thank Mekelle University and Mekelle agricultural research center for providing me an experimental field site to carry out my research. Also thanks to the National Meteorological Organization for providing climate data. My very special thanks go to my promoter and supervisor, Prof. dr. ir Leo Stroosnijder, for accepting me as PhD student in his group and for his efforts which enabled me to benefit from NUFFIC scholarship. Prof. Leo, your very organized follow-up and endless support gave me encouragement, morals, and interest to keep concentrating on my research. I am grateful for your guidance, advices, and constructive comments. I have learned a lot from your useful qualities and enjoyed working under your supervision. I am deeply thankful to my co-supervisor, Dr. Saskia Keesstra for her intellectual advices and interest in my research. Dr. Saskia, you had been very keen to help me and I have benefited a lot from your constructive comments. I shared inspiring discussions during your field supervision visit to Ethiopia which made me to develop tremendous confidence in my work. I would like to thank Dirk Meindertsma for his supports from my first year stay at Wageningen University until he retired. Dirk had special qualities in handling his PhD students. I wish him long prosperous life. I am also grateful to Demie Moore for her special support in language edition/advices. My sincere appreciation goes to Marnella for facilitating housing and other facilities during my last stay at Wageningen University. I would like to thank all those who have contributed to this research works. I was lucky enough to get tremendous technical supports from well qualified local scientists: Dr. Kiros Melles Hadgu, Dr. Solomon Habtu, Dr. Girmay G. Samuel, Dr. Tadesse Dejen, Dr. Mitiku Haile, Dr. Yemane Tsehaye and Dr. Amanuel Zenebe. Your scientific contributions, encouragements, advices and comments were indeed helpful. I am grateful to Dr. Abdulkadir Kedir and Dr. Kendeya G. Hiwet for facilitating many administrative aspects of my research. My sincere appreciations go to Agazi and Lijalem for their helps in providing many scientific equipments and contributing their skills during my research works. I am thankful to Mekelle University staff members who helped me in preparing field layout, field measurements and data collections: Negash Aregay, Tesfakiros Semere, Dr. Haddis Abrha, Afewerk Kebede and Kibrom Berhe. I would like to thank my students Sisay Fntahun, Abrham Tezera, Mache Berhe, Samuel Tafere and Yakob Amare for devoting their time organizing my data. I am grateful for those farmers who spend their time for interviews and group discussions. I would like to thank Wim Spaan, Jan de Graaff, Geert Sterk, Aad Kessler, Saskia Visser and Piet Peters for the warm and unforgettable social events. I would like to thank LDD students: Birhanu, Alemayehu, Desire, Feras, Nadia, Ali, Abraham, Adermus, Charlot, Bony, Rudolf, Monique, Cathelijne and Innocent for the nice friendships. Last but not least I would like to thank my parents for their prayers. My mother passed away in July 2009, just during time of intense data collection. I am thankful to Dr. Girmay G. Samuel, Dr. Haddis Abrha, Dr. Yemane Tsehaye, Assefa Atsbha and Kebede Manjur for encouraging me all the time. I am also very grateful to my wife, Abrehet G. Hiwot, for her patience of loneliness during my absence. Table of Contents Chapter 1 Introduction 1 Chapter 2 A new agro-climatic classification for crop suitability zoning in 7 northern semi-arid Ethiopia. Chapter 3 Assessing drought risk and irrigation need in northern Ethiopia. 23 Chapter 4 Crop coefficient, yield response to water stress and water productivity 47 of teff (Eragrostis tef (Zucc.)). Chapter 5 Simulating yield response to water of teff (Eragrostis tef) with 67 FAO’s AquaCrop model. Chapter 6 Determination of local barley (Hordeum vulgare) crop coefficient and 85 comparative assessment of water productivity for crops grown under the present pond water in Tigray, northern Ethiopia. Chapter 7 Test of AquaCrop model in simulating biomass and yield of water 97 deficient and irrigated barley (Hordeum vulgare). Chapter 8 Risk assessment by sowing date of barley (Hordeum vulgare) in northern Ethiopia. 115 Chapter 9 Effects of tied ridges and mulch on barley (Hordeum vulgare) rainwater 131 use efficiency and production In northern Ethiopia. Chapter 10 Conclusions and synthesis. 147 References 157 Summary 165 Samenvatting 167 PE&RC PhD Education Certificate 171 Curriculum vitae and author’s publications 173 Chapter 1 Introduction Introduction 1.1 Problem definition Droughts are a major obstacle to food security in Ethiopia. Development of strategies to effectively cope with drought and increase crop success is fundamental to ensure food security and improve the livelihood of the people of this country. The Ethiopian economy is highly dependent on agriculture. Agriculture is the largest sector of the economy accounting for 80 – 85 % of the income of its people; and about 46% of its GDP and 90% of its export earnings (FDRE, 1997; UNDP, 2002). Agriculture in Ethiopia consists primarily of small-holder farmers using low level technology in a mixed crop-livestock farming system, and is highly dependent on natural rainfall. The main natural hazard responsible for food shortages in Ethiopia is drought. Food shortages have been one of the most important problems in Ethiopia with, each year on average, 1 to 5 million Ethiopians facing the risk of food insecurity (USAID, 2002). Many people believe that the drought risk is principally associated to rainfall characteristics of the area. Rainfall variability and associated droughts have historically been identified as the major causes of food shortages and famine in the country (Pankhurst and Johnson, 1988). A large part of Ethiopia has a semi-arid climate. The rainfall in semi-arid Ethiopia is characterized by its uncertainty in space and time. Reports show that rainfall variability has caused significant problems for the country’s economy and food production in the last three decades (Tilahun, 1999; Bewket and Conway, 2007). Over the last decade the situation has worsened due to human induced climate change. This climate change seems to have increased the uncertainty and variability in the rainfall, making cropping more difficult. Projections of climate scenarios indicate that crop production may be limited by severe water and heat stress (Vorosmarty et al., 2000). In northern Ethiopia severe droughts took the lives of millions, and destroyed crops and animals in 1971/1972, 1984/1985 and 2002/2003. Tigray is one of the northern regions of Ethiopia, and is the most severely affected by drought. Drought events occur every 2 to 4 years. These frequent droughts cause serious decreases in the income of the people who fully depend on agriculture. Many people live with chronic hunger (Devereux, 2000). On average, nearly 1 million people per year depended on food aid during the period 1995 to 2002 (TDPPC, 2002). People remain vulnerable and desperate as they do not have enough resources to cope with the vagaries of the weather. Crop failure due to occurrence of short and long dry spells is common, yet little is really known about how the seasonal rainfall variability and distribution influences the occurrence of seasonal soil water drought. Furthermore, there is limited understanding of the relation between past rainfall, soil water variability and the resulting crop failures in northern Ethiopia. While crop-climate suitability classifications exist, those currently in use are not very relevant to semi-arid northern Ethiopia. An improved agro-climatic classification will help policy makers, investors and agriculturists derive better crop suitability information and amend some existing cropping limitations, as well as plan for better short- and long-term development strategies under climate change scenarios. In northern Ethiopia, the rainfall is torrential and falls in short intense events which often result in high runoff. Infiltration into the soil is negatively affected by the nature of the rainfall. The high runoff damages crops by taking away the fertile soil and exposing the crop roots to direct sunlight (Nyssen et al., 2005).