A Multlvaviate Time Series Analysis of Agrometeorological Data to Assess the Effect of Climate Variability on Production of Sorghum: The Case of Melkassa, Ethiopia
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Date
2011-06
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Addis Ababa University
Abstract
Climate change affects all economic sectors to some degree, but the agricultural sector is
perhaps the most sensitive and vulnerable. In the last three decades, Ethiopia has been affected
by climare-related hazards. Agriculture, the most dominant sector in the national economy, has
been most at risk because of its dependence on seasonal rainfall. Anticipated climate change has
negatively impacted the agricultural sector due to increased temperatures and decreased or
greater variability in precipitation, leading to increased food insecurity.
The aim of this thesis is to study the effects of rainfall and temperature on sorghum yield over
long period of time.
The study consists of thirty two years consecutive summer seasons total summer rainfall in mm,
average temperature in degree centigrade and sorghum yield of medium maturing Gambella-
1107 variety in quintal per hectare (Qlh) which is used as a control variety in Melkossa
Research Center of E1AR. Multivariate time series analysis that is Vector Auto Regressive model
is used for this study.
The results obtained show that rainfall and yield are highly variable. Rainfall shock has
significant impact on rainfall temperature and yield, temperature shock has a significant impact
on temperature rainfall and yield and also yield shock has a significant impact on yield. It was
observed that rainfall variation could fully be explained by its own innovations. For
temperature, in the first round, 56% variation of temperature has resulted ji-om the shock of its
own innovation and 44% variation resulted from the change in rainfall. Yield variation of up to
48.1% is explained by changes in rainfall amounts, the percentage contribution of yield shock
for its forecast variance is around 48.6%.
There exist high inter annual variability in summer rainfall total which is an evidence to climate
variability in the study area and also yield is highly variable. Past year and following year
rainfall temperature and yield are autocorelated and rainwater is a principal component in
determining sorghum yield.
Keywords: VAR, Sorghum(Gambella#1107 variety), Melkassa
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Keywords
VAR, Sorghum(Gambella#1107 variety, Melkassa