Analysis of Start, End and Length of the Growing Season and Number of Rainy Days in Semi-Arid Central Refit Valley of Oromia State, Ethiopia

Ethiopian agriculture is dominated by small holder farmers with an average per capita land holding of less than a hectare. The production system mainly depends on rain fed system and low input including fertilizer and pesticides used. In order to characterize the climate of Mieso, Melkassa, and Adami Tulu located in CRV of Ethiopia daily climate data were obtained from MARC for Mieso, Melkassa and Ademi Tulu and used for characterization using INSTAT V3.37. The mean start, end of season and length of growing season (LGS) are found to be May 26, September 14, and 99 days at Mieso site; May 27, October 1st and 97 days at Melkassa site; May 26, September 11, and 109 days in Adami Tulu site. The rainy days ranged from 92-165, 92-147, and 92-110 days in Mieso, Melkassa and Adami Tulu, respectively. Hence, developing new varieties and use of appropriate soil moisture conserving tillage practices will enhance adaptation capacity of farmers under changing climate in CRV of Ethiopia. The changes in rainfall conditions have a direct and immediate impact on the performance of agricultural sector as well as on the country’s total GDP. In order to characterize the climate of Mieso, Melkassa, and Adami Tulu located in CRV of Ethiopia daily climate data were obtained from MARC for Mieso, Melkassa and Ademi Tulu and used for characterization using INSTAT V3.37. The seasonal mean rainfall at Mieso, Melkassa and Adami Tulu is 438, 577.7 and 430.3 mm. The probability of occurrence of dry spell lengths of 5, 7, 10, and 15 days reaches minimum value during the peak rainy months and then starts to increase after the end of the rains. Generally, for the study periods the probability of longer dry spells increases rapidly from first dekadal of September onwards. To take risks of longer dry spells and decide to plant during earliest months of the season, farmers should get access to irrigation and also other mechanisms that minimize the loss of moisture from the farm land.