Crop Water Requirement and Crop Coefficient of Tef (Eragrostis tef) in Central Rift Valley of Ethiopia

Tef is the most important native cereal crop to Ethiopia and widely grown under rain-fed agriculture. Irrigation is essential in arid and semi-arid areas where rainfall is unreliable and insufficient for crop production. Rational application of irrigation water is based on the knowledge of crop water requirement. Field study was undertaken at the experimental farm of Melkassa agricultural research center located in the central rift valley of Ethiopia. Non-weighing lysimeter was used to measure daily crop water requirement of tef grown on a clay loam soil. The reference evapotranspiration was determined from daily climatic data using Penman-Monteith method and Kc was obtained from the ratio of measured crop water requirement as obtained from water balance equation to estimated reference evapotranspiration. The measured crop water requirement values tef during growth stages of initial, development, mid-season and late season were 36.4 mm, 109.9 mm, 166.5 mm, and 50.9 mm, respectively. The corresponding Kc-values as a fraction during growth stages were 0.46, 0.88, 1.03 and 0.57. Fifth-order polynomials function was found to fit well to predict the crop coefficient values as functions of days after sowing that can be applicable in similar agro-climatic region for irrigation design and water management practices. Keywords: Crop water requirement, reference evapotranspiration, Kc, drainage lysimeter, tef DOI: 10.7176/JNSR/11-15-04 Publication date:August 31st 202

Crop Coefficient of Haricot Bean at Melkassa, Central Rift Valley of Ethiopia

Crop coefficient (Kc), the ratio of potential crop evapotranspiration to reference evapotranspiration, is an important parameter in irrigation planning and management. However, this information is not available for many important crops. A study was carried out at the experimental farm of Melkassa Agricultural Research Center of Ethiopian Agricultural Research Organization, which is located in a semi arid climate. Four drainage type lysimeters were used to measure the daily evapotranspiration of haricot bean, Awash Melka variety on a clay loam soil. Crop coefficient was developed from measured crop evapotranspiration and reference evapotranspiration calculated using weather data. The measured values of crop coefficient for the crop were 0.34, 0.70, 1.01 and 0.68 during initial, development, mid-season and late-season stages. These locally determined values can be used by irrigation planners and mangers at Melkassa and other areas with similar agroecological conditions

Impact of landscape management scenarios on ecosystem service values in Central Ethiopia

This study aimed at modeling scenarios of future land use and land cover (LULC) change and estimating ecosystem service (ES) values for the year 2051 compared to 2021 in Central Ethiopia. The future LULC changes for the year 2051 were simulated for four scenarios, namely Business-as-Usual (BAU), Rapid Agricultural Expansion (RAE), Ecosystems Protection and Agricultural Development (EPAD) and Landscape Ecosystems Restoration and Conservation (LERC). The four LULC change scenarios were simulated based on anticipated assumptions that were derived from existing spatial policies, a consultation workshop report on scenarios of agricultural development in Ethiopia, suitability analysis, population growth analysis and expert knowledge of the study area characteristics. We used a Multi-Layer Perceptron–Artificial Neuron Network (MLP–ANN) model-based projected LULC for the BAU scenario and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to generate RAE, EPAD and LERC scenarios in the study landscape. The benefit transfer method was used to estimate the total ES values and for trade-off analysis. The result showed that LULC changes in the study area varied across simulated scenarios compared to the base year 2021. Under the BAU and RAE scenarios, cultivated land increased by 146,548 ha (22%) and 193,965 ha (29%), whereas forest, water body, wetland and shrub-bush land were reduced. However, forest cover increased by 31,725 ha and 100,080 ha but bare land was reduced by 8466 ha (21%) and 10,379 ha (25%) under the EPAD and LERC scenarios. The forest cover annual rate of change was 3.2% and 6% under the EPAD and LERC scenarios. As a result, the total ES value increased by USD 24.5 and 78.5 million under the EPAD and LERC scenarios for the year 2051, whereas the total ES value was reduced under the BAU and RAE scenarios by USD 27.1 and 73.2 million. The trade-offs among ecosystem services were significantly synergized under the LERC scenario compared to RAE. Therefore, EPAD and LERC could be used as a reference for sustainable landscape planning and management. Landscape ecosystems restoration integrated with a sustainable agricultural intensification approach would enable us to ensure the sustainability of both agricultural production and ecosystem service synergies without negatively affecting the natural environment

Ecosystem service valuation along landscape transformation in Central Ethiopia

Land degradation and discontinuation of ecosystem services (ES) are a common phe nomenon that causes socio-economic and environmental problems in Ethiopia. However, a dearth of information is known about how ES are changing from the past to the future with regard to land use land cover (LULC) changes. This study aimed at estimating the values of ES based on the past and future LULC changes in central Ethiopia. Maximum likelihood classifier and cellular automata artificial neuron network (CA-ANN) models that integrate the module for land use change evaluation (MOLUSE) were used to classify and predict LULC. The CA-ANN model learning and validation was employed to predict LULC of 2031 and 2051. Following LULC change detection and prediction, the total ES values were estimated using the benefit transfer method. Results revealed that forests, wetlands, grazing lands, shrub-bush-woodlands, and water bodies were reduced by 9755 ha (37%), 4092 ha (38.4%), 21,263 ha (81%), 63,161 ha (25.7%), and 905 ha (1%), respectively, between 1986 and 2021. Similarly, forests, wetlands, grazing lands, shrub-bush lands, and water bodies will experience a decline of 1.5%, 0.5%, 2.6%, 19.6%, and 0.1%, respectively. Meanwhile, cultivated lands, bare-lands, and built-up areas will experience an increase between 1986 and 2051. The estimated total ES values were reduced by US$58.3 and 85.4 million in the period 1986–2021 and 1986–2051. Food production and biological control value increased while 15 other ES decreased throughout the study periods. Proper land use policy with strategic actions, including enforcement laws for natural ecosystems protection, afforestation, ecosystems restoration, and conservation practices, are recommended to be undertaken to enhance multiple ES provision

Quality assessment and evaluation of irrigation water and soil used for maize (Zea mays L.) production in Boloso Sore district, southern Ethiopia

Poor quality of irrigation water and soil are among the major factors determining maize productivity in Ethiopia. This study assessed and evaluated the quality of irrigation water and soil under maize production in Soke and Woybo irrigation schemes in Boloso Sore district, Ethiopia. Four water samples per site per season were collected from the first point of the irrigation schemes and farm gate for dry and rainy seasons in 2019/2020. Soil samples of 108 were collected from 36 points, from which 18 composited samples were taken for laboratory analysis. Results show that irrigation water of the two schemes is non-saline (electrical conductivity  potassium (7.3 mg l−1) > calcium (6.2 mg l−1) > magnesium (3.1 mg l−1). Moderate to severe sodicity (sodium adsorption ratio of 10.9) was also recorded. Sulfate, nitrate, and phosphate contents in water were trace, and increased during rainy seasons in downstream. Textural classes of soils are clay loam to clay, and less compact to restrict root penetration (bulk density ≤1.4 g cm−3), have slow infiltration rate (≤0.13 cm h−1), and medium level of total available water (≤178 mm m−1). Soils are strongly acidic to neutral (pH: 5–6.5), salt-free, and have low soil organic carbon (≤2.1%), low total nitrogen (≤0.1%), low available phosphorus and sulfur, and low Ca2+: Mg2+ ratio. It can be concluded that the irrigation water in the study area has cation imbalance (poor quality) which affects soil quality and maize productivity. Likewise, soils of the study area have poor quality. Lime application, efficient fertilizer use, and organic matter applications can be suggested. Further study on optimizing fertilizer rates and irrigation levels has to be conducted to improve maize productivity

Response of maize to irrigation and blended fertilizer levels for climate smart food production in Wolaita Zone, southern Ethiopia

Sustainable development needs climate-smart food production systems. This study examined maize responses to irrigation levels of 70, 85, and 100% crop evapotranspiration (ETc) and blended fertilizer rates of 0, 50, 100, and 150 kg ha−1, in factorial combinations. Blended fertilizer contains nitrogen, phosphorus, sulfur, and boron (NPSB). A field experiment was conducted for two seasons (2020 and 2021) in a randomized complete block design with three replications. Results indicate that the earliest tasseling (68 days), silking (73.5 days), and maturity (117 days) were recorded at the interaction effect of up to 30% deficit irrigation with 100 kg ha−1 NPSB. In response to the interaction effect of 30% deficit irrigation with the highest fertilizer level, the highest canopy cover (2.5) and stem diameter (4.35 cm) were recorded at 70% ETc × 150 kg ha−1 NPSB. Plants also produced the highest leaf area index (4.47) and height (2.53 m) at full irrigation level with the highest fertilizer. The highest cob length (23.4 cm), number of kernels per cob (586), thousand kernels weight (395g), biomass yield (23.27 ton ha−1), and grain yield (8.8 ton ha−1) were recorded at 100% ETc × 150 kg ha−1 NPSB . The highest harvest index (32.33%) and fertilizer use efficiency (51.1 kg kg−1) were recorded at 85% ETc × 100 kg ha−1 NPSB, and 100% ETc × 50 kg ha−1 NPSB, respectively. The highest water productivity was obtained in response to the main effects of 30% deficit irrigation (2.71 kg m−3) and 150 kg ha−1 NPSB (3.21 kg m−3). The future maize productivity is projected to decrease by up to 15.11% by 2030, 2050, and 2070, under two representative concentration pathways (RCP4.5 and RCP8.5). Based on the results, using 85% ETc with 100 kg ha−1 NPSB is optimum. Policymakers and agricultural offices better consider climate-smart maize production systems in Ethiopia