Feed the Future Innovation Lab for Small-Scale Irrigation
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Item Advances in water resources research in the Upper Blue Nile basin and the way forward: A review(Journal of Hydrology, 2018) Dile, Yihun Taddele; Tekleab, Sirak; Ayana, Essayas K.; Gebrehiwot, Solomon G.; Worqlul, Abeyou W.; Bayabil, Haimanote K.; Yimam, Yohannes T.; Tilahun, Seifu A.; Daggupati, Prasad; Karlberg, Louise; Srinivasan, Raghavan; ElsevierThe Upper Blue Nile basin is considered as the lifeline for ∼250 million people and contributes ∼50 Gm3/year of water to the Nile River. Poor land management practices in the Ethiopian highlands have caused a significant amount of soil erosion, thereby threatening the productivity of the Ethiopian agricultural system, degrading the health of the aquatic ecosystem, and shortening the life of downstream reservoirs. The Upper Blue Nile basin, because of limited research and availability of data, has been considered as the “great unknown.” In the recent past, however, more research has been published. Nonetheless, there is no state-of-the-art review that presents research achievements, gaps and future directions. Hence, this paper aims to bridge this gap by reviewing the advances in water resources research in the basin while highlighting research needs and future directions. We report that there have been several research projects that try to understand the biogeochemical processes by collecting information on runoff, groundwater recharge, sediment transport, and tracers. Different types of hydrological models have been applied. Most of the earlier research used simple conceptual and statistical approaches for trend analysis and water balance estimations, mainly using rainfall and evapotranspiration data. More recent research has been using advanced semi-physically/physically based distributed hydrological models using high-resolution temporal and spatial data for diverse applications. We identified several research gaps and provided recommendations to address them. While we have witnessed advances in water resources research in the basin, we also foresee opportunities for further advancement. Incorporating the research findings into policy and practice will significantly benefit the development and transformation agenda of the Ethiopian government.Item APEX-MODFLOW: A New integrated model to simulate hydrological processes in watershed systems(Environmental Modelling & Software, 2021) Bailey, R. T.; Tasdighi, A.; Park, S.; Tavakoli-Kivi, S.; Abitew, T.; Jeong, J.; Green, C. H. M.; Worqlul, A. W.; Department of Civil and Environmental Engineering, Colorado State University, USA; Blackland Extension and Research Center, Texas A&M AgriLife, USA; US Department of Interior, Bureau of Land Management, USA; INTERA Incorporated, 3838 W. Carson Street, #380, Torrance, CA, 90503, USAAPEX (Agricultural Policy/Environmental eXtender) is an oft-used agroecosystem model but has limited use in groundwater-driven watersheds due to a simplistic representation of groundwater processes. This paper presents the linkage of APEX and the groundwater flow model MODFLOW into a single modeling code. The mapping of recharge, groundwater head, and groundwater-surface water interactions are handled internally via subroutines. The APEX-MODFLOW model is applied to three watersheds in the United States for testing code accuracy and hydrologic state variables and fluxes: the Animas River Watershed, Colorado and New Mexico (3543 km2); the Price River Watershed, Utah (4886 km2); and the Middle Bosque River Watershed, Texas (470 km2). Whereas the hydrology of the Animas River and Price River watersheds is driven by snowmelt and spring runoff, the hydrology of the Middle Bosque River Watershed is driven by summer thunderstorms. The model can be used for scenario analysis in groundwater-driven watersheds.Item Assessing potential land suitable for surface irrigation using groundwater in Ethiopia(Applied Geography, 2017) Worqlul, Abeyou W.; Jeong, Jaehak; Dile, Yihun T.; Osorio, Javier; Schmitter, Petra; Gerik, Thomas; Srinivasan, R.; Clark, Neville; ElsevierAlthough Ethiopia has abundant land for irrigation, only a fraction of its potential land is being utilized.This study evaluates suitability of lands for irrigation using groundwater in Ethiopia using GIS-basedMulti-Criteria Evaluation (MCE) techniques in order to enhance the country's agricultural industry.Key factors that significantly affect irrigation suitability evaluated in this study include physical landfeatures (land use, soil, and slope), climate (rainfall and evapotranspiration), and market access (proximity to roads and access to market). These factors were weighted using a pair-wise comparison matrix,then reclassified and overlaid to identify suitable areas for groundwater irrigation using a 1-km grid.Groundwater data from the British Geological Survey were used to estimate the groundwater potential,which indicates the corresponding irrigation potential for major crops. Results indicated that more than6 million ha of land are suitable for irrigation in Ethiopia. A large portion of the irrigable land is located inthe Abbay, Rift Valley, Omo Ghibe, and Awash River basins. These basins have access to shallowgroundwater (i.e., depth of groundwater less than 20 m from the surface) making it easier to extract. Thecomparison between available groundwater and total crop water requirements indicate that groundwater alone may not be sufficient to supply all suitable land. The study estimates that only 8% of thesuitable land can be irrigated with the available shallow groundwater. However, groundwater is a viableoption for supplementing surface water resources for irrigation in several basins in the countryItem Assessment of smallholder farmers’ demand for and adoption constraints to small-scale irrigation technologies: Evidence from Ethiopia(Agricultural Water Management, 2021) Tesfaye, M. Z.; Balana, B. B.; Bizimana, J.-C.; Arba Minch University, Arba Minch, Ethiopia; University of Milano-Bicocca, Milano, Lombardy, Italy; International Food Policy Research Institute (IFPRI), Abuja, Nigeria; Texas A&M University, College Station, Department of Agricultural Economics, TX, USAIncreasing agricultural productivity through irrigation technologies is recognized as an effective way to improve smallholders’ livelihoods and food security in developing countries. However, most smallholder farmers do not have access to irrigation technologies. Using a double-bounded contingent valuation survey data from smallholders in Ethiopia and probit and bivariate probit models, this paper analyzes smallholder farmers’ demand for agricultural water lifting technologies (WLTs) and the factors affecting the demand for these technologies. Assessment of farmers’ preferences among three water lifting technologies available in local markets (motorized pump, rope and washer and pulley) show that farmers prefer motorized pumps to pulley or rope and washer technologies. Use of motorized pumps is more efficient and save labour than pulley or rope and washer technologies. However, results show that smallholders are constrained by inadequate access to financing options to adopt more efficient and labour-saving water lifting technology and hence operate below the production possibility frontier. Enhanced access to finance could help ease this constraint and allow smallholders to acquire more efficient irrigation technologies, enhance adoption and improve productivity. With a growing population pressure and land fragmentation in rural Ethiopia, the livelihoods of smallholders depend mainly on the meagre land endowment they possess. Increasing the productivity of land using yield enhancing technologies, particularly multiple cropping per year via small-scale irrigation is key to improve their livelihoods. Targeted interventions are thus warranted to mitigate the key adoption constraints such as improving access to credit and technical know-how of smallholders.Item Assessment of Suitable Areas for Home Gardens for Irrigation Potential, Water Availability, and Water-Lifting Technologies(Water, 2018) Assefa, Tewodros; Jha, Manoj; Reyes, Manuel; Srinivasan, Raghavan; Worqlul, Abeyou W.; MDPIThe study was conducted in Lake Tana Basin of Ethiopia to assess potentially irrigable areas for home gardens, water availability, and feasibility of water-lifting technologies. A GIS-based Multi-Criteria Evaluation (MCE) technique was applied to access the potential of surface and groundwater sources for irrigation. The factors affecting irrigation practice were identified and feasibility of water-lifting technologies was evaluated. Pairwise method and expert’s opinion were used to assign weights for each factor. The result showed that about 345,000 ha and 135,000 ha of land were found suitable for irrigation from the surface and groundwater sources, respectively. The rivers could address about 1–1.2% of the irrigable land during dry season without water storage structure whereas groundwater could address about 2.2–2.4% of the irrigable land, both using conventional irrigation techniques. If the seven major dams within the basin were considered, surface water potential would be increased and satisfy about 21% of the irrigable land. If rainwater harvesting techniques were used, about 76% of the basin would be suitable for irrigation. The potential of surface and groundwater was evaluated with respect to water requirements of dominant crops in the region. On the other hand, rope pump and deep well piston hand pump were found with relatively the most (26%) and the least (9%) applicable low-cost water-lifting technologies in the basin.Item Berken plow and intercropping with pigeon pea ameliorate degraded soils with a hardpan in the Ethiopian highlands(Geoderma, 2021) Fenta, H. M.; Hussein, M. A.; Tilahun, S. A.; Nakawuka, P.; Steenhuis, T. S.; Barron, J.; Adie, A.; Blummel, M.; Schmitter, P.; Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Ethiopia; International Water Management Institute (IWMI), Addis Ababa, Ethiopia; Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA; International Water Management Institute, Colombo, Sri Lanka; International Livestock Research Institute (ILRI), Addis Ababa, EthiopiaClosing the yield gap and enhancing efficiency in rainfed maize production systems in Ethiopia requires urgent action in increasing the productivity of degraded agricultural land. The degradation of land through continuous compaction and decline in the organic matter has resulted in a wide-spread formation of a hardpan that restricts deep percolation, prevents plant root development, and, ultimately can lead to increased erosion. Studies exploring practical low-cost solutions to break the hardpan are limited in Ethiopia. The main objective was to evaluate soil mechanical (i.e. modified plow or Berken plow) or biological intervention (i.e. intercropping with pigeon pea) effectiveness to enhance soil water management and crop yield of rainfed maize systems whilst reducing soil erosion and runoff. Five farm fields, each including four plots with different tillage treatments, were monitored during two rainy seasons in 2016 and 2017. The treatments were: (i) farmers practice under conventional (CT) tillage; plots tilled three times using an oxen driven local plow Maresha, (ii) no-till (NT), (iii) Berken tillage (BT), plots tilled three times using an oxen pulled Berken plow, and (iv) biological (CT + Bio), tap-rooted pigeon pea intercropped with maize on plots conventionally tilled. Results showed that mean tillage depth was significantly deeper in the BT (28 cm) treatment compared to CT and CT + Bio (18 cm) treatments. Measured soil penetration resistance significantly decreased up to 40 cm depth under BT and maize roots reached 1.5 times deeper compared to roots measured in the CT treatment. Under BT, the estimated water storage in the root zone was estimated at 556 mm, 1.86 times higher compared to CT, 3.11 times higher compared to NT and 0.89 times higher compared to CT + Bio. The positive effects on increased water storage and root development resulted in an average increase in maize grain (i.e. 15%, 0.95 t ha−1) and residual above ground biomass (0.3%, 6.4 t ha−1) leading to a positive net benefit of 138 USD ha−1 for the BT treatment compared to the CT treatment. The negative net benefit obtained under CT and CT+Bio was mainly related to the high labor cost related to plowing, weeding, planting, and fertilizer application whilst in the NT this was related to the significantly lower maize yields. The positive effects in the BT treatment, and to some extent the CT+Bio treatment show great potential for smallholder rainfed maize systems where degraded soils with hardpans and high variability in rainfall prevail.Item Beyond the drinking glass: expanding our understanding of water-nutrition linkages(Feild Exchange, 2017) Mekonnen, D. K.Water access and management play central roles in determining nutritional outcomes. Water-for-nutrition is most often approached from a WASH (water, sanitation and hygiene) perspective, where the aim is to improve water quality and practices for domestic water supply, thus reducing the burden of water-related diseases in a population. A WASH focus for improving nutritional outcomes is especially pertinent, given recent evidence highlighting the role of diarrhoeal disease and environmental enteropathy in determining child stunting. However, there are a number of water-nutrition pathways in addition to WASH that would benefit from greater attention in research and discussion. A session aimed at expanding our understanding of water-nutrition linkages was organised during the 2016 Stockholm World Water Week (26 August to 5 September, 2016). The session was organised by the International Food Policy Research Institute (IFPRI) in collaboration with the Center for Development Research (ZEF) at the University of Bonn, USAID, and Texas A&M University.Item Business Model Scenarios and Suitability: Smallholder Solar Pump-based Irrigation in Ethiopia(IWMI, 2018) Otoo, Miriam; Lefore, Nicole; Schmitter, Petra; Barron, Jennie; Gebregziabher, GebrehaweriaThis report outlines a business model approach to assessing the feasibility and for encouraging investment in smallholder solar pump irrigation. It also proposes a new methodology for mapping the suitability of solar energy-based irrigation pumps. The proposed business model framework and the methodology for suitability mapping are applied to Ethiopia as a case study, based on data from existing case studies and reports. A brief analysis outlines the regulatory and institutional context for investment in solar pump irrigation, and the ways in which it both constrains and attempts to support investment. The report identifies and outlines three business model scenarios that present opportunities for investing in smallholder solar pump-based irrigation, which would contribute towards sustainable intensification for food and nutrition security. The business model scenarios are based on the value proposition of supplying water to smallholder farmers for irrigated agricultural production. Analysis of potential gains and benefits suggests that direct purchase of solar pumps by farmers is feasible, and that out-grower schemes and pump supplier options with bundled financing offer promising solutions. The potential constraints that different investors may face in up-scaling the business models are also discussed, particularly within institutional, regulatory and financial contexts. The report provides development actors and investors with evidence-based information on the suitability and sustainability of solar pump irrigation in Ethiopia, as well as suggestions for helping to enable smallholders to invest in individually-owned, smallholder photovoltaic (PV) solar pumps.Item Characterizing shallow groundwater in hillslope aquifers using isotopic signatures: A case study in the Upper Blue Nile basin, Ethiopia(Journal of Hydrology: Regional Studies, 2021) Setargie, T. A.; Tilahun, S. A.; Schmitter, P.; Moges, M. A.; Gurmessa, S. K.; Tsunekawa, A.; Tsubo, M.; Berihun, M. L.; Fenta, A. A.; Haregeweyn, N.; Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia; The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori, 680-8553, Japan; The International Water Management Institute, Nile Basin and East Africa Office, Addis Ababa, Ethiopia; Department of Geology and Geophysics, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia; Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan; International Platform for Dryland Research and Education, Tottori University, 1390 Hamasaka, Tottori, 680-0001, JapanStudy region: Robit-Bata watershed, Upper Blue Nile basin, Ethiopia. Study focus: Stable isotopes of water (Oxygen-18 and Deuterium) were used as tracers to estimate the contribution of groundwater in shallow hillslope aquifers to streamflow in the Robit-Bata watershed. To assess the spatiotemporal variability of shallow groundwater and develop a hydrograph separation technique, we collected rainfall, shallow groundwater, and streamflow samples and analyzed their δ18O and δ2H isotopic compositions. The local meteoric water line (LMWL) and local evaporative line (LEL) of the study area were determined and compared with the global meteoric water line (GMWL). A standard unweighted two-component isotope-based hydrograph separation model was used to determine the percentage contribution of shallow groundwater to streamflow. New hydrological insights for the region: The LMWL (δ2H = 8.63·δ18O + 18.2) mostly showed heavy isotopic enrichment relative to GMWL, and the LEL (δ2H = 5.45·δ18O + 6.96) indicated isotopic enrichment compared to Ethiopian lakes. Shallow groundwater responded rapidly to rainfall, with good spatial correlation depending on topographic positions of wells. Pre-event water contributed <50% to peak discharge in July, but >90% when the watershed reached maximum storage. This finding gives insight towards the predominant runoff generation process and has significant implications for sustainable dry season irrigation expansion in the area as the sub-surface flow drains out of the watershed from October onwards reducing water tables in the shallow wells.Item Conservation Agriculture Saves Irrigation Water in the Dry Monsoon Phase in the Ethiopian Highlands(Water, 2019) Belay, Sisay A.; Schmitter, Petra; Worqlul, Abeyou W.; Steenhuis, Tammo S.; Reyes, Manuel R.; Tilahun, Seifu A.; MDPIWater resources in sub-Saharan Africa are more overstressed than in many other regions of the world. Experiments on commercial farms have shown that conservation agriculture (CA) can save water and improve the soil. Nevertheless, its benefits on smallholder irrigated farms have not been adequately investigated, particularly in dry monsoon phase in the Ethiopian highlands. We investigated the effect of conservation agriculture (grass mulch cover and no-tillage) on water-saving on smallholder farms in the Ethiopian highlands. Irrigated onion and garlic were grown on local farms. Two main factors were considered: the first factor was conservation agriculture versus conventional tillage, and the second factor was irrigation scheduling using reference evapotranspiration (ETo) versus irrigation scheduling managed by farmers. Results showed that for both onion and garlic, the yield and irrigation water use efficiency (IWUE) was over 40% greater for CA than conventional tillage (CT). The soil moisture after irrigation was higher in CA compared with CT treatment while CA used 49 mm less irrigation water. In addition, we found that ETo-based irrigation was superior to the farmers’ irrigation practices for both crops. IWUE was lower in farmers irrigation practices due to lower onion and garlic yield responses to overirrigation and greater water application variability.Item Conservation agriculture with drip irrigation: Effects on soil quality and crop yield in sub-Saharan Africa(Journal of Soil and Water Conservation, 2020) Assefa, Tewodros; Jha, Manoj; Reyes, Manuel; Worqlul, Abeyou W.; Doro, L.; Tilahun, S.; MDPIThe traditional agriculture production system in sub-Saharan Africa (SSA) caused significant soil erosion and degradation of soil quality. In addition, dependability of rainfall for irrigation needs limits the crop production. Advanced agricultural practices are thus needed at the local level to sustain the livelihood of smallholder farmers in the region. In this study, conservation agriculture (CA) practice with drip irrigation technology was compared (using field experiments and watershed modeling) with the traditional conventional tillage (CT) practice for its potential in improving soil quality and crop productivity in the region. Biophysical data were collected (2015 to 2017) from a total of 43 paired plots (CA and CT) at four study sites in SSA: Dangishita and Robit in Ethiopia, Yemu in Ghana, and Mkindo in Tanzania. The Agricultural Policy/Environmental eXtender (APEX) model was calibrated and validated with reasonable efficiency in simulating crop yields for both CA and CT practices; average PBIAS ≤±12% and ≤±11%, for CA and CT. The impact of the CA system on soil quality (soil carbon [C] and nitrogen [N]) was analyzed based on the well-tested model prediction results. The total C and N were increased under CA across the study sites on average by 6% and 4.1%, when compared to CT over the study period. Both the experiment and model prediction showed that crop yield was significantly improved by CA—on average 37.4% increases across the sites when compared to CT. Conservation agriculture with drip irrigation was an efficient local strategy to improve crop production in the region while enhancing the ecosystemItem Conservation and Conventional Vegetable Cultivation Increase Soil Organic Matter and Nutrients in the Ethiopian Highlands(Water, 2022) Belay, S. A.; Assefa, T. T.; Worqlul, A. W.; Steenhuis, T. S.; Schmitter, P.; Reyes, M. R.; Vara Prasad, P. V.; Tilahun, S. A.; Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar, Ethiopia; Blackland Research Center, Texas A&M AgriLife Research, Temple, TX 76502, USA; Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14850, USA; International Water Management Institute, Yangon 11081, Myanmar; Sustainable Intensification Innovation Laboratory, Department of Agronomy, Kansas State University, Manhattan, Kansas, KS 66506, USAAgriculture in Africa is adversely affected by the loss of soil fertility. Conservation agriculture (CA) was introduced to curb the loss of soil fertility and water shortages and improve crop productivity. However, information on how CA practices enhance soil quality and nutrients is scarce in the sub-Saharan Africa context. The objective of this study was to investigate the effects of CA and conventional tillage (CT) on soil organic matter and nutrients under irrigated and rainfed vegetable on-farm production systems. During the dry and wet monsoon phases in the northern Ethiopian Highlands, a four-year experiment with CA and CT was carried out on ten vegetable farms under rainfed and irrigated conditions. Although the increase in concentration of organic matter in CA was generally slightly greater than in CT, the difference was not significant. The average organic matter content in the top 30 cm for both treatments increased significantly by 0.5% a−1 from 3% to almost 5%. The increase was not significant for the 30–60 cm depth. The total nitrogen and available phosphorus concentrations increased proportionally to the organic matter content. Consequently, the extended growing season, applying fertilizers and livestock manure, and not removing the crop residue increased the nutrient content in both CA and CT. The increase in CA was slightly greater because the soil was not tilled, and hay was applied as a surface cover. Although CA increased soil fertility, widespread adoption will depend on socioeconomic factors that determine hay availability as a soil cover relative to other competitive uses.Item Constraints of small-scale irrigated fodder production and nutrition assessment for livestock feed, a case study in Ethiopia(Agricultural Water Management, 2021) Worqlul, A. W.; Dile, Y. T.; Schmitter, P.; Bezabih, M.; Adie, A.; Bizimana, J.-C.; Srinivasan, R.; Lefore, N.; Clarke, N.; Blackland Research Center, Texas AgriLife Research, Temple, TX, USA; Spatial Sciences Laboratory, Texas A&M University, College Station, TX, USA; International Water Management Institute C/o Irrigation Head Office, Yangon, Myanmar; International Livestock Research Institute, Addis Ababa, Ethiopia; Department of Agricultural Economics, Texas A&M University, College Station, TX, USA; The Norman Borlaug Institute for International Agriculture, Texas A&M AgriLife Research, College Station, TX, USALivestock is an integral part of the agricultural system in sub-Saharan Africa, serving as a food source, income, fertilizer, and power for farming and transportation. However, the productivity of the livestock system has been hampered due to a lack of sufficient quantity and quality feed. This study evaluates the gaps and constraints of fodder and nutritional potential for livestock feed using small-scale irrigation (SSI). The study comprised of 30 randomly selected farmers from two different ecological zones in Ethiopia. Half of the farmers cultivated Napier grass (Pennisetum purpureum) in the Robit watershed in northern Ethiopia, and the other half cultivated mixed vetch (Lathyrus cicera) and oats (Avena sativa) in Lemo watershed in southern Ethiopia. The Soil and Water Assessment Tool (SWAT) and Agricultural Policy Environmental eXtender (APEX) were applied in an integrated manner to assess the impacts of SSI at the watershed and field-scale levels, respectively. The watershed-scale analysis showed that there is a substantial amount of surface runoff and shallow groundwater recharge that could be used for dry season fodder production using irrigation. Field data calibrated APEX model indicated that Napier yield could be maximized with 550 mm of water in Robit watershed. While in the Lemo watershed, maximum vetch and oats yield may be achieved with 250 mm of water. The major constraints for Napier and oats production in the study sites were soil fertility, especially nitrogen and phosphorus, and vetch production was limited by high temperature. Fodder samples were collected at the time of harvest to evaluate feed quality. The nutritional analysis indicated that Napier grass has a higher dry matter and ash (mineral) content compared to oats and vetch. However, vetch has higher crude protein content (18%) compared to Napier (10%) and oats (6%). Overall the study indicated that cultivating vetch provided superior performance in terms of providing quality feed and environmental services.Item Constraints of small-scale irrigated fodder production and nutrition assessment for livestock feed, a case study in Ethiopia(Agricultural Water Management, 2021) Worqlul, W. A.; Dile, T. Y.; Schmitter, P.; Bezabih, M.; Adie, A.; Bizimana, J-C; Srinivasan, R.; Lefore, N.; Clarke, N.; Blackland Research Center, Texas AgriLife Research, Temple, TX, USA; Spatial Sciences Laboratory, Texas A&M University, College Station, TX, USA; International Water Management Institute C/o Irrigation Head Office, Yangon, Myanmar; International Livestock Research Institute, Addis Ababa, Ethiopia; Department of Agricultural Economics, Texas A&M University, College Station, TX, USA; The Norman Borlaug Institute for International Agriculture, Texas A&M AgriLife Research, College Station, TX, USALivestock is an integral part of the agricultural system in sub-Saharan Africa, serving as a food source, income, fertilizer, and power for farming and transportation. However, the productivity of the livestock system has been hampered due to a lack of sufficient quantity and quality feed. This study evaluates the gaps and constraints of fodder and nutritional potential for livestock feed using small-scale irrigation (SSI). The study comprised of 30 randomly selected farmers from two different ecological zones in Ethiopia. Half of the farmers cultivated Napier grass (Pennisetum purpureum) in the Robit watershed in northern Ethiopia, and the other half cultivated mixed vetch (Lathyrus cicera) and oats (Avena sativa) in Lemo watershed in southern Ethiopia. The Soil and Water Assessment Tool (SWAT) and Agricultural Policy Environmental eXtender (APEX) were applied in an integrated manner to assess the impacts of SSI at the watershed and field-scale levels, respectively. The watershed-scale analysis showed that there is a substantial amount of surface runoff and shallow groundwater recharge that could be used for dry season fodder production using irrigation. Field data calibrated APEX model indicated that Napier yield could be maximized with 550 mm of water in Robit watershed. While in the Lemo watershed, maximum vetch and oats yield may be achieved with 250 mm of water. The major constraints for Napier and oats production in the study sites were soil fertility, especially nitrogen and phosphorus, and vetch production was limited by high temperature. Fodder samples were collected at the time of harvest to evaluate feed quality. The nutritional analysis indicated that Napier grass has a higher dry matter and ash (mineral) content compared to oats and vetch. However, vetch has higher crude protein content (18%) compared to Napier (10%) and oats (6%). Overall the study indicated that cultivating vetch provided superior performance in terms of providing quality feed and environmental services.Item Deep Tillage Improves Degraded Soils in the (Sub) Humid Ethiopian Highlands(Land, 2019) Abidela Hussein, Misbah; Muche, Habtamu; Schmitter, Petra; Nakawuka, Prossie; Tilahun, Seifu A.; Langan, Simon; Barron, Jennie; Steenhuis, Tammo S.; MDPIIntensification of rainfed agriculture in the Ethiopian highlands has resulted in soil degradation and hardpan formation, which has reduced rooting depth, decreased deep percolation, and increased direct runoff and sediment transport. The main objective of this study was to assess the potential impact of subsoiling on surface runoff, sediment loss, soil water content, infiltration rate, and maize yield. Three tillage treatments were replicated at five locations: (i) no tillage (zero tillage), (ii) conventional tillage (ox-driven Maresha plow, up to a depth of 15 cm), and (iii) manual deep ripping of the soil’s restrictive layers down to a depth of 60 cm (deep till). Results show that the posttreatment bulk density and penetration resistance of deep tillage was significantly less than in the traditional tillage and zero-tillage systems. In addition, the posttreatment infiltration rate for deep tillage was significantly greater, which resulted in significantly smaller runoff and sedimentation rates compared to conventional tillage and zero tillage. Maize yields were improved by 6% under deep tillage compared to conventional tillage and by 29% compared to no tillage. Overall, our findings show that deep tillage can be effective in overcoming some of the detrimental effects of hardpans in degraded soils.Item The determinants of irrigation participation and its impact on the pastoralist and agro-pastoralists income in Ethiopia: A review study.(Cogent Food & Agriculture, 2019) Asrat, Dagninet; Anteneh, Adugnaw; Taylor & FrancisThis review identified factors that determine the decision of a household to participate in irrigation, and its impact on the income of pastoralists and agro-pastoralists. In Ethiopia, agriculture is the basic economic sector in which the country relies for its social and economic development. In Ethiopia, the majority of population directly or indirectly engaged in agriculture where around 95% of the country’s agricultural output is produced by smallholder farmers. However, the sector has remained in its rudimentary stage, especially in dry lands of Ethiopia. The recurrent drought is the key factor, causes vulnerability to agro-pastoralists and pastoralists. To alleviate the problem, the government of Ethiopia has taken irrigation agriculture subsector as the main strategies in the overall country’s development agenda and gives high priority to irrigation development, including smallholder and large-scale commercial schemes to exploit the untapped resources. Ethiopia is considered as the water tower of Africa. However, currently, only 5% is actually irrigated, which is very low. The basic factors influencing the decision of smallholder farmers to participate in irrigation farming are demographic, socioeconomic and institutional characteristics. Hence, to make considerable improvement on the decision to adopt irrigation, actions should be taken by household heads, government of Ethiopia, national and international organizations.Item Economic and food security effects of small-scale irrigation technologies in Northern Ghana(Elsevier, 2019) Balana, Bedru; Bizimana, Jean-Claude; Richardson, James W.; Lefore, Nicole; Adimassu, Zenebe; Herbst, Brian K.Small-scale irrigation (SSI) technologies can be useful not only to increase crop productivity and income but also as a viable adaptation practice to climate variability. A farm simulation model (FARMSIM) and data from selected SSI technologies piloted in northern Ghana under the ‘Feed the Future-Innovation Lab for Small Scale Irrigation’ (ILSSI) project were used to assess the economic feasibility of the SSI technologies and their potential to improve income and nutrition of smallholder farm households. Three dry season irrigated crops (onion, corchorus, amaranthus) grown under three agricultural water management regimes were analysed. Results show that adoption of the SSI technologies could increase the net farm profit by 154%–608% against the baseline depending on the ‘crop type - SSI technology’ combination. Nutrition levels also improved significantly as a result of the improvements in crop yields due to irrigation and use of complementary inputs. However, the results further reveal that the options that utilize capital-intensive SSI technologies such as solar-powered water pumps to grow high value cash crops are constrained by the high investment cost. Currently, farmers tend to choose low-cost SSI technologies such as a traditional watering-cans, which generate low economic returns. Improving access to credit or alternative financing schemes could mitigate the capital constraints and enable smallholders to gain more benefits from participating in market-oriented high-value irrigated productionItem Effect of climate change on land suitability for surface irrigation and irrigation potential of the shallow groundwater in Ghana(Computers and Electronics in Agriculture, 2019) Worqlul, Abeyou W.; Dile, Yihun T.; Jeong, Jaehak; Adimassu, Zenebe; Lefore, Nicole; Gerik, Thomas; Srinivasan, Raghavan; Clarke, Neville; ElsevierEstimating the potential land resources suitable for irrigation and evaluating the possible impact of climate change on land suitability is essential for planning a sustainable agricultural system. This study applied a GIS-based Multi-Criteria Evaluation (MCE) technique to evaluate the suitability of land for irrigation in Ghana for a baseline period (1990 to 2010) and future time horizons 2050s (2041 to 2060) and 2070s (2061 to 2080). Key factors considered to evaluate the suitability of the land for irrigation include biophysical features (such as climate, land use, soil, and slope) and socioeconomic factors (such as proximity to roads and population density). These factors were weighted using a pairwise comparison matrix then reclassified and overlaid on a 30 m grid to estimate the irrigation potential of the country. Groundwater data from the British Geological Survey (BGS) were superimposed onto the land suitability map layer to evaluate the irrigation potential and the accessibility of shallow groundwater with simple water lifting technologies. Downscaled and bias-corrected future climate data from HadGEM2-ES under Representative Concentration Pathways (RCP) 4.5 emission scenario were used to represent the future climate horizon. Due to climate change, on average, rainfall will increase by 15 mm and 20 mm from the baseline period in the 2050s and 2070s, respectively. The average temperature shows a consistent increase in the majority of Ghana and a higher rate of increase is expected in the 2070s. Consequently, the rising temperature will increase the potential evapotranspiration by 6.0% and 7.6% in the 2050s and 2070s, respectively. The suitability analysis indicates that approximately 9% of the country is suitable for surface irrigation under the baseline period. A large portion of the potential land is located in the southwestern part of the country. The potential suitable land has an average groundwater access of 12 m from the surface with an average borehole potential yield of 2.5 L/second, which makes it favorable for utilization of simple water lifting technologies. Due to climate change, 9.5% of the suitable land will become unfavorable for irrigation in 2050s, and it is expected to reach 17% in 2070s.Item The effect of nitrogen-fertilizer and optimal plant population on the profitability of maize plots in the Wami River sub-basin, Tanzania: A bio-economic simulation approach(Agricultural Systems, 2020) Kadigia, I. L.; Richardson, J. W.; Mutabazi, K. D.; Philip, D.; Mourice, S. K.; Mbungu, W.; Bizimana, J.-C.; Sieber, S.; School of Agricultural Economics and Business Studies, Sokoine University of Agriculture, P.O. Box 3007, Morogoro, Tanzania; Soil-Water Management Research Programme, Sokoine University of Agriculture, P.O. Box 3003, Morogoro, Tanzania; Department of Agricultural Economics, Texas A&M University, 600 John Kimbrough Blvd/AGLS Blg, College Station, TX 77843-2124, USA; Department of Crop Science and Horticulture, Sokoine University of Agriculture, P.O. Box 3005, Morogoro, Tanzania; Department of Engineering Sciences and Technology, Sokoine University of Agriculture, P.O. Box 3003, Morogoro, Tanzania; Leibniz-Centre for Agriculturald Landscape Research, Eberswalder Straße 84, 15374 Müncheberg, Germany; Department of Agricultural Economics, Faculty of Life Sciences Thaer-Institute, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, GermanyMaize (Zea mays L.) is the essential staple in sub-Saharan Africa (SSA) and Tanzania in particular; the crop accounts for over 30% of the food production, 20% of the agricultural gross domestic product (GDP) and over 75% of the cereal consumption. Maize is grown under a higher risk of failure due to the over-dependence rain-fed farming system resulting in low income and food insecurity among maize-based farmers. However, many practices, including conservation agriculture, soil and water conservation, resilient crop varieties, and soil fertility management, are suggested to increase cereal productivity in Tanzania. Improving planting density, and the use of fertilizers are the immediate options recommended by Tanzania's government. In this paper, we evaluate the economic feasibility of the improved planting density (optimized plant population) and N-fertilizer crop management practices on maize net returns in semi-arid and sub-humid agro-ecological zones in the Wami River sub-Basin, Tanzania. We introduce a bio-economic simulation model using Monte Carlo simulation procedures to evaluate the economic viability of risky crop management practices so that the decision-maker can make better management decisions. The study utilizes maize yield data sets from two biophysical cropping system models, namely the APSIM and DSSAT. A total of 83 plots for the semi-arid and 85 plots for the sub-humid agro-ecological zones consisted of this analysis. The crop management practices under study comprise the application of 40 kg N-fertilizer/ha and plant population of 3.3 plants/m2. The study finds that the use of improved plant population had the lowest annual net return with fertilizer application fetching the highest return. The two crop models demonstrated a zero probability of negative net returns for farms using fertilizer rates of 40 kg N/ha except for DSSAT, which observed a small probability (0.4%) in the sub-humid area. The optimized plant population presented 16.4% to 26.6% probability of negatives net returns for semi-arid and 14.6% to 30.2% probability of negative net returns for sub-humid zones. The results suggest that the application of fertilizer practices reduces the risks associated with the mean returns, but increasing the plant population has a high probability of economic failure, particularly in the sub-humid zone. Maize sub-sector in Tanzania is projected to continue experiencing a significant decrease in yields and net returns, but there is a high chance that it will be better-off if proper alternatives are employed. Similar studies are needed to explore the potential of interventions highlighted in the ACRP for better decision-making.Item Effect of rainfall variability and gauge representativeness on satellite rainfall accuracy in a small upland watershed in southern Ethiopia(Hydrological Sciences Journal, 2020) Tessema, K. B.; Haile, A. T.; Amencho, N. W.; Habib, E.; Arba Minch Water Technology Institute (AWTI), Arba Minch University, Arba Minch, Ethiopia; International Water Management Institute, Addis Ababa, Ethiopia; Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, USAThe actual accuracy of satellite rainfall products is often unknown due to the limitation of raingauge networks. We evaluated the effect of gauge representativeness error on evaluation of rainfall estimates from the CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) rainfall product. The reference data were collected using an experimental raingauge network within a small watershed of 1690 ha, which is comparable to the CHIRPS resolution. The study applied a total bias approach, decomposed into hit, missed and false biases, and an error-variance separation method to evaluate gauge representativeness error at the scale of CHIRPS pixel size, as well as modeled the spatial correlation field of daily rainfall with a three-parametric exponential model. The results indicate that the gauge representativeness error is still too large to ignore in evaluating satellite rainfall. However, it is significantly affected by sample size and caution should be exercised when the rainfall data has a small sample size.