Article InformationKnowledge of crop evapotranspiration (ETc), the combined process of evaporation and plant transpiration, is important in agriculture for scheduling farm operations and designing and managing irrigation and drainage systems. Development of crop coefficient (Kc) can enhance crop evapotranspiration (ETc) estimates in specific crop growth stages. However, locally determined Kc information is not available for many important crops in Ethiopia. This research was, therefore, conducted to determine growth stage specific Kc and crop water use for sorghum (Sorghum bicolor L.) var. Gambella-1107 at the Melkassa Agricultural Research Center which is located in a semi arid climate zone in Ethiopia. Drainage type lysimeter was used to measure Gambella-1107 crop water use under water balance system on a clay loam soil and local weather data were used to determine the reference evapotranspiration (ETo). Crop coefficient was developed from measured ETc and ETo calculated using weather data. The growth stages of the crop were assessed as the seasonal change of plant height (pH), leaf area (LA) and leaf area index (LAI). The yield obtained was 5.3 t ha -1 and the measured LAI were 0.2, 4.2, 4.9 and 1.6 at the initial, development, midseason and late season stages, respectively. The maximum LAI was achieved when the plants reach their maximum height at mid-season stage with high crop evapotranspiration due to leaf enlargement that increases transpiration. The measured ETc values were 53.8, 138.5, 214.4, and 94.0 mm during the initial, development, midseason and late-season stages, respectively, and the seasonal total value was 500.7 mm. The calculated Kc values for the crop were 0.45, 0.83, 1.18 and 0.78 during the initial, development, mid-season and late-season stages, respectively. These values were greater than those reported in FAO publication for sorghum varieties which could be a result of soil, climate and crop genetic differences. This suggests the need for developing site-specific Kc values for proper irrigation management.

Exploring micro-level evidences is critical to fine tune effective adaptation options to cope with the adverse impact of climate change. In this regard, detailed studies on climate change adaptation options are not available in the study areas. Hence, the objective of this study was to assess farmers' climate change adaptation options and determinant factors that influence their choice. Data were collected from 253 respondents randomly using probability proportional to the sizes (PPS) of the population of each district and peasant association from which sample households to be drawn. Descriptive statistics were employed to assess adaptation options while the multinomial logit model (MNL) was used to identify factors influencing households' choices. The results revealed that farmers use change in crop type /variety, soil and water conservation practices, crop diversification, change in planting date and irrigation practices as climate change adaptation options. Educational level of the household head, age of the household head, sex of the household head, farm income, access to extension service, access to credit, access to climate information and agro-ecological settings were the most important determinant factors that affect significantly the choice of farmers to climate change adaptations. Therefore, an effort that enhances farmers' awareness to climate change and creates the capacity to adopt climate resilient options is an important strategy that should be considered by a variety of societal groups, including policy makers, and farmers support organizations.

Assessment of climate variability at local level has enormous advantage in Ethiopia, where the driver of the economy is agriculture. This study was conducted to analysis rainfall and temperature variability to guide sorghum production in Miesso. Daily climate data was obtained from the National Meteorological Service Agency of Ethiopia (NMA). Temporal rainfall variability was assessed through the timing of onset date, end date, length of growing season and dry spell length using INSTAT climate guide. Temperature variability was examined in terms of pattern, trend and probability of exceedence. The long-term annual rainfall showed high variability from year to year with 25% coefficient of variation. Seasonally, the MAM total rainfall showed high variability than the JJAS total rainfall at Miesso. Rainfall onset date and length of growing season were highly variable. Higher minimum temperature values (>16 o C) are observed from April to August whereas maximum temperature reaches its lowest level in December, but increase again to maximum in June and start to decline as of July. The minimum and maximum temperatures showed an increasing trend both seasonally and annually. To avert the risks of rainfall and temperature variability the use of seasonal climate outlook is recommended for adjusting farm operations and farming system decisions in Miesso areas.

Vertisols cover large part of the high rainfall areas of Ethiopia. However, the potential of these soils is not well exploited because of heavy water logging during the main rain season. A study was conducted to investigate the interactive effects of soil drainage and fertilizer application on the productivity of Vertisols. Factorial combinations of four planting beds (Broadbed and furrow (BBF) with 100 cm bed size, broadbed and furrow with 80 cm bed size, ridge and furrow (RF) with 30 cm bed size, and flatbed) and two fertilizer levels (unfertilized and fertilized with 64 kg N ha-1 & 46 kg P2O5 ha-1) in RCBD were experimented for the sustainable use and improved productivity of Vertisols in Northeastern Ethiopia in the 2006/2007 cropping season. Results revealed that ridge and furrow bed (RF) drained more excess water than the broadbed and furrow beds (BBF) and the flatbed (F), but with yield penalties. Soil drainage using broadbed and furrows (BBF) and nitrogen and phosphorus fertilization reduced days to heading and maturity by 12 and 15%, respectively. The broadbed and furrow and the nitrogen and phosphorus fertilization package increased grain yield by 90%, grain nitrogen and phosphorus uptakes by 183 and 252%, and stover nitrogen and phosphorus uptakes by 152 and 121%. Thus, planting in broadbed and furrows (BBF), disregard of the bed size, with fertilizer application is recommended for bread wheat production on vertisols in Northeastern Ethiopia.

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