Characterization of Agriculturally Important Rainfall variables for agricultural decision making, Hawassa, Ethiopia Group members Mr. Gizachew Legesse (EIAR/MARC) Mr. Minilik Tsega (EIAR/ HQ) Mr. Eshetu Zewidu (EIAR/MARC) Mr. Eskinder (EIAR/Mehoni ARC)

In Central Rift valley of Ethiopia, agriculture interfaces with extreme temporal and spatial variability of climate factors. Amongst which rainfall is the most variable and the most important that greatly influence agricultural production and productivity. For these reason, accurate analysis of rainfall is needed to generate valuable agro- climatic information that helps to reduce risks level of crop production. Introduction

Study site Rainfall analysis was performed for Hawassa zuria district that is found in Sothern Nation Nationality People (SNNP) regional state of Ethiopia.

1 Collecting and organizing climate data and establishing flat databases suited for INSTAT and Genstat software 2 Turning climate data into useful information through analysis and interpretation 3 Application of the information for better decision making Approach: Generation of Climate information through analysis

Rainfall variables and criteria for rainfall characterization 1 Start of the Season (SOS) Criteria: 3 days RT > 20mm and no dry spell of >10 days for the next 30 days 2 End of the Season (EOS) Criteria: any day after first of September, when soil water starts to be at permanent deficit (WB < 50%). 3 Length of Growing Period (LGP) Criteria: EOS -SOS 4 Total Season Water (TSW) Criteria: The sum of rainfall total b/n SOS and EOS 5. Risk of a long dry spell The risk of longer dry spell of 5, 7, 10 and 15 days after sowing for any potential sowing date

Crop Coefficient for crop water requirement satisfaction index for maize crop variety having 140 day maturity period Value of crop coefficient for maize crop was taken from LEAP software (fig) Crop coefficient was interpolated for 14 dekade of the given cropping season using INSTAT software Computing CWRSI for maize variety having 140 day maturity period

I. Monthly Rainfall total ( ) Rainfall amount from April to September is greater than 100 mm per month.

I. Probability of occurrence of rainfall ( ) The overall chance of rainfall reveled that the probability of occurrence of rainfall in Hawassa ranges from 0.45 to 5.5 from 2 nd dekade of April to the last dekade of September

Average daily rainfall total per rainy day ( ) The average daily rainfall total per rainy days is 6.56 mm

Onset of rainy season( ) Based on the T- test result from the two onset definition (SOSWD) and (SOS ), there is no significance difference in risk of failure (Replanting needed three times ). The onset of rainy season in Hawassa ranges from April 1 to June 14.

Onset and Cessation of rainy season( ) The mean onset and cessation of rainy season are 110 th (April 2 nd dekade) and 251 th ( September 1 st dekade) DOY, respectively. Thus, the growing season accommodate about 141 days length of growing periods.

Probability of occurrence of LGP( ) From the result, the probability of occurrence of LGP, the chance of getting 140 days and less within the season is about 50%. one can recommend crop variety having 140 and less maturity period.

Risk of Dry spell, Hawassa, Ethiopia Analysis of the risk of dry spell longer than 5, 7, 10, and 15 days shows that the risk of dry spell of longer than 10 and 15 days is less than 1 % in the growing period (April 2 nd dekade to September 1 st dekade). While, 5 and 7 day risk of dry spell gradually increases in month of May about 2.5 and 6.2 %. The result informed that farmer can use 140 day crop variety while considering the adjustment of planting time not coincide the risk of dry spell in the month May with that of sensitive growth stage of the selected crop (like flowering time).

Summary of rainfall variables(SOS, EOS,LGP and SRT)( )

Crop Water Requirement Satisfaction Index for maize crop variety having 140 day maturity period

Crop water requirement satisfaction index for 140 maize variety CWRSI analytical result of 31 year cropping season reveals that Maize crop having 140 maturity period was fully satisfied in 11 years. whereas in less than 70 % is only 1 years (2000). This may cause yield reduction.

Rainfall characterization analytical result raveled that in Hawassa zuria districts have unimodal rainfall characteristics with average starting of main rainy season in 2 nd dekade while ending in 1 st dekade of September. The risk of dry spell longer than 7,10 and 15 days is relatively low (<3%). Thus, season can accommodate 140 LGP having 500mm on average. CWRSI result indicate that maize crop varieties having 140 day maturity period have been satisfied from seasonal rainfall. Based on the result, maize crop having 140 day maturity period can be successfully grown the Hawassa zuria districts A knowledge of rainfall characteristics in terms of onset and cessation date, length of growing period, seasonal rainfall amount and duration of intermittent dry spell as well as CWRSI, are very useful for planning various agricultural operations. Conclusion

Thank you!