Assessment of Stage-Wise Deficit Furrow Irrigation Application on Maize Production at Koga Irrigation Scheme, Blue Nile River Basin, Ethiopia

Efficient irrigation management has an imperative role in managing integrated water resources. Deficit irrigation water application is among the most effective water management solutions. This study was conducted with the aim of evaluating the performance of stage-wise deficit irrigation (DI) application on irrigation efficiencies and to identify crop growth stages during which the crop can withstand water deficit with limited effect on yield and water productivity (WP). Maize (Melkassa-4 type) was selected as test crop as it is known to respond well to deficit irrigation. The experiment was conducted at Koga Irrigation Scheme, Blue Nile River Basin. The field experiment was arranged in randomized complete block design (RCBD) with three replications. The result showed that level of stage-wise deficit irrigation water application had a significant (P<0.05) impact on performance indices except distribution uniformity. Application efficiency increased with deficit level increases. The maximum application efficiency (83.5%) was noted when 0.25ETc was applied throughout the growing season. Effect of stage-wise application level had a significant (P<0.05) effect on agronomic parameters. The highest yield (58.92 qt/ha) was obtained when full irrigation was applied in all growth stages. The highest Physical water productivity (CWP) (1.65 kg/m3) and economic water productivity (CWP) (4.17 Birr/m3) were obtained when 50% deficit applied during 2nd and 3rd growth stages. On average, the crop was found to be moderately sensitive to water deficit since the average seasonal maize response factor (Ky) (1.04) value is slightly greater than one. In conclusion, this study showed that much water is saved when the crop is stressed by 50% during 2nd and 3rd growth stages.Keywords: Deficit irrigation, irrigation performance indices, Koga irrigation scheme, stage-wise, water productivity

Evaluation of Stage-Wise Deficit Furrow Irrigation Application on Water Advance - Recession Time and Maize Yield Components at Koga Irrigation Scheme, Ethiopia

Well-organized irrigation management has an imperative role for integrated water resources management. Deficit irrigation water application is among the most effective water management solutions. This study was conducted with the aim of evaluating the performance of stage-wise deficit irrigation (DI) application on water advance - recession time and maize yield components. Maize (Melkassa-4 type) was selected as test crop as it is known to respond well to deficit irrigation. The experiment was conducted at Koga Irrigation Scheme, Blue Nile River Basin. The field experiment was arranged in randomized complete block design (RCBD) with three replications. The result showed that level of stage-wise deficit irrigation water application had a significant (P<0.05) impact on mean advance time. The maximum advance rate across growth stages (0.144 m/s) was noted during the development stage. Effect of stage-wise application level had a significant (P<0.05) effect on agronomic parameters. The maximum (147.3 cm) and minimum (4.3 cm) plant height were recorded during late season and first growing stage at full irrigation level (Dall,0 (T6)) and application of 0.25ETc (Dall,75 (T4)) throughout the growth stages, respectively. Maximum (8.55cm) and minimum (3.17 cm) stalk diameter at knee height were obtained in treatment Dall,0 (T6) and Dall,75 (T4). Maximum (2) and minimum (1.07) number of ears per plant were obtained in full irrigation treatment (Dall,0 (T6)) and 0.25ETc irrigation treatment (Dall,75 (T4)) throughout the growing season, respectively. The highest yield (58.92 qt/ha) was obtained when full irrigation was applied in all growth stages. The maximum (164.28 qt/ha) and minimum (130.34 qt/ha) aboveground biomass were obtained when 100% of ETc and 0.25 of ETc were applied starting from the first to the end growth stages. Keywords: Agronomic parameters, Deficit irrigation, Koga irrigation scheme, Stage-wise, Water advance - recession time

Growth and yield components of tomato as influenced by nitrogen and phosphorus fertilizer applications in different growing seasons

Tomato is an important cash crop in Central Rift Valley of Ethiopia. However, the yield is constrained by poor soil fertility management and lack of appropriate/adequate fertilizers rates recommendation. Experiments were conducted at Melkassa on station with the objectives of evaluating effect of N and P fertilizer applications on growth and yield, and determining optimal requirements for tomato. The experiments were conducted under both cool season furrow irrigated and rain-fed conditions with variable fertility status of the fields. The treatments consisted of four rates of nitrogen (0, 50, 100 and 150 kg N ha-1) and four rates of P (0, 46, 92 and 138 kg ha-1). The experiments were laid out in a CRBD in a factorial arrangement and replicated three times using Melkashola variety. Data on growth and canopy characteristics such as plant height and stem diameter, main lateral branch length, canopy width and depth were measured from selected plants. Some of the growth and yield components such plant height, canopy diameter, canopy width, stem diameter, lateral branch length, total dry mass above the ground per plot, shoot fresh and dry weight, marketable and unmarketable fruit yield and total yield at harvest were measured were assessed. Maximum fruit yield was estimated from regression lines of applying 105 kg N ha-1 and 85 kg P ha-1 under furrow irrigated experiment (continuously cultivated field). However, the highest fruit yield was from application of 40 kg N ha-1 and 10 kg ha-1 for the rainfed experiment (relatively fertile field). Thus, results of both experiments were averaged to propose on farm verification of N and P requirement of tomato, N 73 kg ha-1 and P 48 kg ha-1 around Melkassa and similar soil types.Keywords: furrow irrigated, rain-fed, season, tomato, inorganic N and P fertilize

Ensuring sustainable water security through sustainable land management: Research evidences for policy

Sustainable land management (SLM) practices is a key to reducing rates of land degradation and has proven to ensure water security by increasing soil moisture availability, decreasing surface runoff, decreasing soil erosion, increasing infiltration, and decreasing flood discharge. Land degradation is adversely affecting over 75% of the Earth's land surface and could exceed 90% by 2050. The rate of soil erosion will increase by 66% during the period 2015–2070. Over 85% of the land in Ethiopia is moderately to very severely degraded at an estimated cost of $4.6 billion annually. So far, only 18% of Ethiopia's cropland area is covered by SLM practices for the last 40 years of intensive interventions. Water security, in turn, is a powerful and multidimensional option that includes water availability, accessibility, use, and stability across time. In Ethiopia, though, the interconnections between SLM and water security are intimate and numerous, their linkage is very loose and yet to be understood. Ethiopia is among the 16 LDCs and is critically water-insecure, implying that abundant natural water availability does not necessarily ensure water security as it might be poor water quality, inaccessible, and unsafe. Hence, national and local level of SLM and water security linkages, impacts, and policy implications must come on board in the least developing countries like Ethiopia. Therefore, SLM-water security policy is crucial in successful SLM because governments/higher officials are capable of promoting well-informed water security decisions

Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia

CITATION: Shiferaw, H. et al. 2021. Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia. Scientific Reports, 11:2688,doi:10.1038/s41598-021-81776-6.The original publication is available at https://www.nature.comDense impenetrable thickets of invasive trees and shrubs compete with other water users and thus disrupt ecosystem functioning and services. This study assessed water use by the evergreen Prosopis juliflora, one of the dominant invasive tree species in semi-arid and arid ecosystems in the tropical regions of Eastern Africa. The objectives of the study were to (1) analyze the seasonal water use patterns of P. juliflora in various locations in Afar Region, Ethiopia, (2) up-scale the water use from individual tree transpiration and stand evapotranspiration (ET) to the entire invaded area, and 3) estimate the monetary value of water lost due to the invasion. The sap flow rates of individual P. juliflora trees were measured using the heat ratio method while stand ET was quantified using the eddy covariance method. Transpiration by individual trees ranged from 1–36 L/day, with an average of 7 L of water per tree per day. The daily average transpiration of a Prosopis tree was about 3.4 (± 0.5) mm and the daily average ET of a dense Prosopis stand was about 3.7 (± 1.6) mm. Using a fractional cover map of P. juliflora (over an area of 1.18 million ha), water use of P. juliflora in Afar Region was estimated to be approximately 3.1–3.3 billion m3/yr. This volume of water would be sufficient to irrigate about 460,000 ha of cotton or 330,000 ha of sugar cane, the main crops in the area, which would generate an estimated net benefit of approximately US$320 million and US$ 470 million per growing season from cotton and sugarcane, respectively. Hence, P. juliflora invasion in the Afar Region has serious impacts on water availability and on the provision of other ecosystem services and ultimately on rural livelihoods.https://www.nature.com/articles/s41598-021-81776-6Publisher's versio

Technical and Institutional Evaluation of Geray Irrigation Scheme in West Gojjam Zone, Amhara Region, Ethiopia

Abstract: The technical and institutional performance evaluation of Geray Irrigation Scheme was made in order to identify management practices for implementation to improve the system operation and the performance of the irrigation system. The evaluation was made based on the selected performance indicators such as conveyance efficiency, application efficiency, water delivery performance, and maintenance indicators. The availability of institutional and support services were also investigated through a questionnaire administered to beneficiary farmers and other stakeholders. The results obtained showed that the main and tertiary canal conveyance efficiencies were 92 and 82 percents respectively. Many of the secondary and tertiary canals are poorly maintained and many of the structures are dysfunctional. Application efficiency monitored on three farmers' plot located at different ends of a given secondary canal ranges from 44 to 57 percent. Water delivery performance was only 71% showing a very substantial reduction from the design of the canal capacity. Maintenance indicator evaluated in terms of water level change (31.9%) and effectiveness of the infrastructures showed that the scheme management was in a very poor shape. Dependability of the scheme evaluated in terms of duration and irrigation interval showed that the scheme is performing below the intended level. The 47% of the land initially planned for development is currently under irrigation while there is no change in the water supply indicating that the sustainability of the scheme is in doubt. The cooperative support services that had been rendered to the beneficiaries in the past four years were found to be minimal. Moreover, there were few indicators that show the production was market oriented. The evaluation clearly revealed the fact that conflict resolution remains to be the duty of the local community authorities and Water User Associations (WUA) has no legal right to enforce its bylaws. In conclusion, the overall technical adequacy of the scheme is rated very poor requiring tremendous mobilization of the community to sustainably manage it. Proper institutional setup needs to be in place, and WUA needs to be more empowered in order to enforce its by-laws

Understanding Future Climate in the Upper Awash Basin (UASB) with Selected Climate Model Outputs under CMIP6

Climate change makes the climate system of a given region unpredictable and increases the risk of water-related problems. GCMs (global climate models) help in understanding future climate conditions over a given region. In this study, 12 GCMs from the CMIP6 (coupled model intercomparison project six) were evaluated and ranked based on their abilities to describe the historical observed series. The ensemble mean of bias-adjusted best five models of average annual precipitation showed an increment with an uncertainty range of (2.0–11.9) and change in the mean of 6.4% for SSP2-4.5 and (6.1–16.1) 10.6% for SSP5-8.5 in 2040–2069 relative to the historical period. Similarly, for 2070–2099, increments of (2.2–15.0) 7.9% and (11.8–29.4) 19.7% were predicted for the two scenarios, respectively. The average annual maximum temperature series showed increments of (1.3–2.0) 1.6 °C for SSP2-4.5 and (1.7–2.3) 2.0 °C for SSP5-8.5 in 2040–2069. At the same time, increments of (1.7–2.3) 2.0 °C and (2.8–3.2) 3.0 °C were predicted for 2070–2099. Furthermore, it was predicted that the average annual minimum temperature series will have increments of (1.6–2.3) 2.0 °C and (2.2–2.9) 2.5 °C for 2040–2069 and (2.1–2.7) 2.4 °C and (3.7–4.2) 4.0 °C for 2070–2099 for the two scenarios, respectively. An increase in precipitation with increased land degradation in the sub-basin results in a higher risk of flood events in the future. Improved soil and water conservation practices may minimize the adverse impacts of future climate change on the loss of agricultural productivity