Climate change is described as the most universal and irreversible environmental problem facing the planet Earth. While climate change is already manifesting in Ethiopia through changes in temperature and rainfall, its magnitude is poorly studied at regional levels. The objective of this paper was to assess and quantify the magnitude of future changes of climate parameters using Statistical Downscaling Mode (SDSM) version 4.2 in Amhara Regional State which is located between 8°45‘N and 13°45‘N latitude and 35°46‘E and 40°25‘E longitude. Daily climate data (1979- 2008) of rainfall, maximum and minimum temperatures were collected from 10 observed meteorological stations (predictand). The stations were grouped and compared using clustering and Markov chain model, whereas the degree of climate change in the study area was estimated using the coupled HadCM3 general circulation model (GCM) with A2a emission scenarios (Predictors). Both maximum and minimum temperatures showed an increasing trend; the increase in mean maximum temperature ranges between 1.55°C and 6.07°C and that of the mean minimum temperature ranges from 0.11°C and 2.81°C. While the amount of annual rainfall and rainy days decreased in the study Regions in the 2080s. The negative changes in rainfall and temperature obtained from the HadCM3 model in the current study are alarming and suggest the need for further study with several GCM models to confirm the current results and develop adaptation options

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For ensuring food demand of the fast growing population in developing countries, quantification of crop yield gaps and exploring production constraints are very crucial. Sorghum is one of the most important climate change resilient crops in the rainfed farming systems of semi-arid tropics. However, there is little information about yield gaps and production constraints. This study aimed at analysing existing yield gaps and exploring major constraints of sorghum production in Southwest Ethiopia. A crop simulation model approach using AquaCrop and DSSAT was used to estimate potential yield and analyse the yield gaps. Model calibration and evaluation was performed using data from field experiments conducted in 2018 and 2019. Sorghum production constraints were assessed using a survey. The actual and water-limited yield of sorghum ranged from 0.58 to 2.51 and 3.6 to 6.47 t/ha, respectively for the period 2003–17. The regional yield gaps of sorghum for the targeted period were 3.02–3.95 t/ha with a mean value of 3.51 t/ha. Majority of respondent farmers considered seasonal rainfall risk (98%), poor soil fertility (86%), lack of improved varieties (78%) and inadequate weed management (56%) as major factors responsible for the existing yield gaps. The mean exploitable yield gap (2.5 t/ha) between water-limited and actual yield showed the level of existing opportunity for improvement in the actual productivity of sorghum. The gaps also call for introduction of proper interventions such as adoption of improved varieties, planting date adjustment, conservation tillage, fertilizer application and on time weed management.

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Understanding rainfall variability is important to establish crop calendar related agronomic decisions. To this end, we defined start and end of seasons, analyzed dry spell and evaluated conditional risks of alternative planting dates using a thirty years daily rainfall data across southern central rift valley of Ethiopia. Results showed that the probability of annual rainfall being greater than 1000 mm was 97, 24, 94, and 61%, in Dilla, Bilate, Shamana, and Hawassa clusters, respectively. The variability of annual total rainfall in the lowland areas of Dilla and Bilate was above 25%, whereas for Shamana and Hawassa was below 20%. Variability of seasonal rainfall during FMAM was 33.7%, which is higher than ONDJ (27.1%) and JJAS (27.9%), which could lead to maize plants suffering moisture stress during FMAM season. The onset of rains had variability of 29.2, 19.5, 17.5 and 26.5%, and also LGP showed variability of 22.8, 22.1, 21.2 and 20.3% in Shamana, Bilate, Hawassa, and Dilla clusters, respectively. Moreover Shamana, Bilate, Hawassa and Dilla clusters are hit by agricultural drought in one out of 2.61, 2.3, 2.5 and 2.5 years, respectively. Model based analysis of conditional risk of farmers planting dates also showed a success rate of less than 10, 7, 40 and 63% for maize variety in Shamana, Bilate, Hawassa and Dilla clusters, respectively. However, the success rate of risk taker farmers’ is higher than anticipated by the model. The farmers who take risk were encouraged in Shamana cluster by local edaphic, physiographic, socioeconomic and climatic differences. Hence, there is a need to seek real time local agro-metrological advisory and follow the necessary tactical and strategic farming decisions. Moreover, there is also a need to incorporate local factors with modern climate models to obtain synchronized calendar estimates.

The dry land areas of Ethiopia account for more than 66.6% of total land area, and are substantial crop producing areas fall within the semi-arid parts. As a result, crops experience moisture stress at any time during their growth stage. The first action to improve agricultural production in the dry land areas is to apply moisture conservation techniques and then use the limited water efficiently for enhancing water productivity. A study was conducted at Holte kebelle of Dirashae district from April 1, 2016-July 31, 2016 to evaluate effects of conventional practice and straw mulch applications on soil moisture conservation and yield of sorghum under rainfed agriculture with six levels of sorghum straw mulch. The experiment was designed as a single factor experiment in randomized complete block design and replicated four times. Soil moisture has been taken for six times of 30 cm interval up to sorghum root depth (90 cm) in 3 weeks interval and analyzed volumetric moisture content. Physical and chemical properties, Field Capacity and Permanent Wilting Point in respective depths were analyzed. The analysis of variance indicated that there was highly significant difference (p ≤ 0.05) for soil moisture contents determined at 0-30 cm, 30-60 cm and 60-90 cm at different sorghum growth stages and straw applied. 2.2 and 3.0 ton/ha straw mulch prolonged the days to harvesting due to more moisture conservation in the soil profile and significant in growth and yield parameters. The maximum volumetric soil moisture content was recorded in 2.2 and 3.0 ton/ha straw mulch, which were between the Field Capacity and Permanent Wilting Point at different growth stages of sorghum however, grain yield was higher in 2.2 t/ha. Based on the experiment therefore, application of 2.2 ton/ha of sorghum straw mulch was found more effective in conserving soil moisture for maximum yield under rain-fed agricultural system better than other treatments.

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