Spatio-temporal variability and rainfall trend affects seasonal calendar of maize production in southern central Rift Valley of Ethiopia

Abstract

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.

Linking Climate Change Information with Crop Growing Seasons in the Northwest Ethiopian Highlands

“…Our results align with [61], who emphasized the significant variability in seasonal rainfall, especially during the cropping season, potentially resulting in moisture stress for maize plants and impacting the LGP. A slightly similar result for LGP, ranging between 137 and 205 days for the NW Ethiopian highlands, has been reported in the mapping of climate vulnerability and poverty in Africa (current condition of 2000) by [62,63] also suggested a planting date in April and an LGP of 180 days for maize (grain) in East Africa's high-altitude areas. The LGP estimation obtained in both time periods has a minimum LGP ≥ 118 days, which is above the threshold LGP (90 days).…”

Exploring adaptation responses of maize to climate change scenarios in southern central Rift Valley of Ethiopia

“…Shamana cluster have a mean minimum and maximum temperature of 15.5 and 26.4 °C, respectively. Similarly Bilate, Hawassa and Dilla clusters have mean minimum and maximum temperature of 19.3 and 28.4 °C, 14.2 and 27.1 °C and 15.8 and 28.0 °C, in respective areas 42 .…”

“…The long term average annual rainfall for Shamana, Bilate, Hawassa and Dilla clusters is 972.0 ± 97.8 mm, 758.7 ± 125.8 mm, 953.9 ± 57.5 mm and 1298.2 ± 70.4 mm 42 , respectively. About 33.0 and 42.9% of the average annual rainfall in Shamana cluster is received during ONDJ and JJAS period, respectively.…”

“…Southern central Rift Valley of Ethiopia is one of the most vulnerable regions to climate risks, where increased temperatures and changes in rainfall patterns have been altering the evapotranspiration rate and reducing water availability for maize crop 41 , 42 . Moreover, soil conditions have been changing due to the associated land degradation processes over the years and hence the old management recommendations may not be efficient, thus making generation of new adaptation options a necessity.…”