_____________________________________________________________________________________________________ *Corresponding author: E-mail: dejeneab@gmail.com; International Journal of Plant & Soil Science 21(6): 1-17, 2018; Article no.IJPSS.39076 ISSN: 2320-7035 Nitrate Leaching under Farmers’ Fertilizer and Irrigation Water Use in the Central Rift Valley of Ethiopia Dejene Abera 1,2* , Kibebew Kibret 2 , Sheleme Beyene 3 and Fassil Kebede 4 1 Ethiopian Institute of Agricultural Research, Melkassa Research Centre, P.O.Box 436, Adama, Ethiopia. 2 School of Natural Resources Management and Environmental Sciences, College of Agriculture and Environmental Sciences, Haramaya University, P.O.Box 138, Dire Dawa, Ethiopia. 3 Department of Plant and Horticultural Science, College of Agriculture, Hawassa University, P.O.Box 05, Hawassa, Ethiopia. 4 Ethiopian Environment and Forest Institute, P.O.Box 24536, Addis Ababa, Ethiopia. Authors’ contributions This work was carried out in collaboration between all authors. Author DA designed the study, wrote the protocol, managed the field work, performed the statistical analysis, and wrote the first draft of the manuscript. The co-authors read the proposal and the manuscript and gave feedback for the improvement of the study. All authors read and approved the final manuscript. Article Information DOI: 10.9734/IJPSS/2018/39076 Editor(s): (1) Aamir Raina, Department of Botany, Aligarh Muslim University, Aligarh, India. Reviewers: (1) Marija Ćosić, University of Belgrade, Republic of Serbia. (2) Mustafa Ünlü, Cukurova University, Turkey. Complete Peer review History: http://www.sciencedomain.org/review-history/23545 Received 3 rd December 2017 Accepted 9 th February 2018 Published 8 th March 2018 ABSTRACT In conventional furrow irrigated agriculture, excess water often causes leaching of nitrate-nitrogen. This experiment was aimed at quantifying nitrate leaching under farmers’ fertilizer and irrigation water use practices. It involved factorial combination of four rates of nitrogen fertilizer (0, 92, 184, and 368 kg N ha -1 ) and two levels of irrigation (100% crop water requirement =1.00 CWR and farmers’ practice =1.25 CWR). It was conducted in onion (Allium cepa L.) planted drainage lysimeter at Melkassa Agricultural Research Center in 2015/16 cropping season. Nitrogen loss for the production season was determined from leachate collected every 10+ 3 days interval. Nitrogen Original Research Article