Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat Utilization of aquaculture drainage for enhancing onion crop yield under surface and subsurface drip irrigation systems Azza I.E. Soliman a , M.M. Morad a , Kamal I. Wasfy a, *, M.A.M. Moursy b a Agricultural Engineering Department, Faculty of Agriculture, Zagazig University, Egypt b Water Management Research Institute, National Water Research Center, Egypt ARTICLE INFO Keywords: Aquaculture farms Groundwater resource Performance evaluation Onion yield ABSTRACT The main objective of the present study is to improve onion crop yield using aquaculture drainage under surface and subsurface drip irrigation systems. Field experiments are carried out on onion crop under conditions of two different water resources (groundwater and aquaculture drainage), two types of filters (screen filter for groundwater, while screen, sand and combined screen-sand filters for aquaculture drainage) and four different pressures (1.0, 1.2, 1.4 and 1.6 bar). The performance of the tested drip irrigation systems is evaluated based on filtration efficiency, discharge reduction, application efficiency, emitters clogging, emission uniformity, onion yield and water-use efficiency. The obtained experimental results show that irrigation with aquaculture drainage gives the highest onion yield of 19.17 Mg/fed for surface drip irrigation and 17.03 Mg/fed for subsurface drip irrigation compared to groundwater, which gives 17.55 Mg/fed for surface irrigation and 14.20 Mg/fed for subsurface irrigation. Surface drip irrigation achieves the lowest emitter clogging (5.98 % for groundwater and 5.86 % for aquaculture drainage) and the highest emission uniformity (90.22 % for groundwater and 89.91 % for aquaculture drainage) in comparison with a subsurface drip irrigation system that gives the lowest emitter clogging (7.98 % for groundwater and 7.55 % for aquaculture drainage) and the highest emission uniformity (91.04 % for groundwater and 90.54 % for aquaculture drainage) at 1.6 bar pressure. It is recommended to use aquaculture drainage for operating surface drip irrigation systems under pressure of 1.4 bar, using combined screen-sand filters for aquaculture drainage filtration, while screen filter for groundwater filtration. 1. Introduction Water for agriculture is crucial to the future of global food security because it uses more than 80 % of total water resources. However, the continued increase in demand for water by nonagricultural uses, as urban and industrial uses, has put the irrigation water demand in a closer examination and threatened food security. Now, with a global focus on sustainable development, especially in the agricultural sector, more efforts have been put into improving resource usage (Boyd et al., 2008). In general, the continuous reduction in water resources in the world, Egypt, in particular, has forced farmers to use other alternative resources. Aquaculture is an important source of non-traditional water that can be exploited for irrigation because it contains nutrients useful for the plant. It provides a unique way to participate towards socio-economic development and food security, during the multiple and sustainable use of water resources (Rana et al., 2005). Fish excrete waste nitrogen, in the form of ammonia which converted to nitrite and then to nitrate by bacteria, directly into the water through their gills (Nakada et al., 2007). Fish excreted nutrients directly by the microbial breakdown of organic wastes to be absorbed by crops. Fish feed supplies most of the nutrients required for crop growth (Abdelraouf and Hoballah, 2014). Reuse of aquaculture water can be considered as a solution of new ir- rigation water resources. This technology will enhance the efficiency and productivity of water use by plants in fish disposal without using fertilizers (Mustapha et al., 2014). Aquaculture effluents contain ap- propriate nutrients (nitrogen and phosphorus) that can be used by plants (Yildiz et al., 2017). The use of drainage water of fish farms (DWFF) for wheat irrigation were compared to canal freshwater (IW). The results showed that the wheat yield under DWFF was higher than IW treatment by between 11 and 51 % in 2014 and between 8 and 38 % in 2015. This is due to the additional amount of dissolved organic ni- trogen and other nutrients inherent in DWFF (Abdelraouf and Ragab, 2017). https://doi.org/10.1016/j.agwat.2020.106244 Received 19 October 2019; Received in revised form 2 May 2020; Accepted 3 May 2020 ⁎ Corresponding author. E-mail addresses: zezosalho@gmail.com (A.I.E. Soliman), drmorad555@yahoo.com (M.M. Morad), kamal.moursy@gmail.com (K.I. Wasfy), mohamed_anter@nwrc.gov.eg (M.A.M. Moursy). Agricultural Water Management 239 (2020) 106244 0378-3774/ © 2020 Elsevier B.V. All rights reserved. T