Vol.:(0123456789) 1 3 Water Conservation Science and Engineering (2023) 8:26 https://doi.org/10.1007/s41101-023-00201-3 RESEARCH Determination of Optimum Water Requirement and Irrigation Interval for Upland Rice at Fogera, Ethiopia Huluager Ayanaw 1  · Abebech Abera 2,3  · Ashebir Haile 4,5  · Hannibal Lemma 2 Received: 2 November 2022 / Revised: 2 November 2022 / Accepted: 8 June 2023 © The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd. 2023 Abstract Irrigation development is very much needed in developing countries as it enhances land, water, and labor productivity and improves the use of agricultural inputs. Ethiopia has 39.35 M ha of rice potential area, under this 3.7 M ha is irrigable. Regardless of the potential, the country is importing a huge amount of rice to fll the increasing food demand, and irrigated rice production was not practiced in the potential area. Determining crop water requirements and irrigation scheduling of rice are supremely important to improve rice production. The goal of this study is to determine yield response of upland rice under optimal irrigation scheduling in the Fogera plain. Thirty-one-year climate data of the study area was used to compute the reference crop evapotranspiration and efective rainfall using CROPWAT model decision support software. The research was conducted by fve experimental treatments; 20% recommended manageable allowable depletion (MAD) of rice as a control (100%), 60%, 80%, 120%, and 140% of the recommended MAD. Among the treatments, the combination of short irrigation intervals (4 day) with high irrigation amounts (651 mm) was found at 60% of recommended MAD levels. The optimum depletion level based on the highest yield (7164 kg/ha) 5 days short irrigation interval was obtained at 80% of recommended MAD. Therefore, optimum irrigation schedule was decided at 80% of the recommended MAD for Fogera plain. Irrigation Engineers, breeders, agronomists, and pathologist researchers should integrately investigate irrigated rice in diferent potenetial area. Keywords Irrigation scheduling · Manageable allowable depletion · Upland rice · NERICA-4 · Fogera plain Introduction Irrigation development is very much needed in developing countries as it enhances land, water, and labor productivity and improves the use of agricultural inputs. Ethiopia has an irrigation potential of 5.3 M ha of which 3.7 M ha can be developed using surface water sources, and 1.6 M ha using groundwater and rainwater management [1]. Based on the potential irrigation in Ethiopia is regarded as a fun- damental approach for reducing poverty and ensuring food security [2]. Irrigation development is critical for Ethiopia’s agricultural development to be sustainable and reliable. In Ethiopian agriculture, irrigation can enhance the income of smallholder farmers who live on a subsistence basis [3]. Irrigation development is an essential tool to promote lengthy economic growth, rural development, food security, and alleviating poverty [4]. To assist the irrigation devel- opment, adequate irrigation water needs to be distributed efciently for the crops at the right time. Correct irrigation scheduling would limit over, and/or under-irrigation situ- ations, and thus, help to avoid water loss due to deep per- colation and runof, and crop water stress. Rice is a new introduction to the country; its importance is well familiar as the production area reporting of about 10,000 ha in 2006 has increased to over 50,000 ha in 2018 [5]. In Ethiopia rice is classifed as the fourth, “National Food Security Crop” next to wheat, maize, and tef [6]. According to Mustofa * Huluager Ayanaw huluayanaw25@gmail.com 1 Jimma Agricultural Research Center, Ethiopian Institute of Agricultural Research, Addis Ababa, Jimma, Ethiopia 2 Faculty of Civil and Water Resources Engineering, Bahir Dar University, Bahir Dar, Ethiopia 3 Blue Nile Water Institute, Bahir Dar University, Bahir Dar, Ethiopia 4 African Center of Excellnec for Water Mnagement, Addis Ababa University, Addis Ababa, Ethiopia 5 Ethiopian Institut of Agricultural Research, Debre Zeit Agricultural Research Center, Addis Ababa, Ethiopia