Effects of Climate Variability on Maize Yield in Nakuru County, Kenya
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Date
2019-05
Authors
Koimbori, Jackson Kinyanjui
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
The current climate in East Africa is characterised by large variability in rainfall and
temperature with occurrence of extreme events such as prolonged and severe droughts that
have led to increased cases of crop failure, hunger and destruction of habitats. This study
analyzed the effects of climate variability on maize yield among farm holders in Bahati Sub-
County, Kenya for the period 1985 to 2015. The specific objectives of this study were: to
establish climate variability trends in rainfall and temperature experienced by farm holders in
Bahati Sub-County, to analyze the effects of climate variability on maize yield in Bahati Sub-
County and to identify and evaluate the existing climate variability adaptation strategies
practised by farmers in Bahati Sub-County, Kenya. The climate parameters used included
rainfall onset, rainfall cessations, seasonal rain, annual rainfall, annual mean temperature,
maximum and minimum temperature. A descriptive case study was used relying on both
primary and secondary data. Stratified random sampling technique was used to select 394
households from Dundori, Kabatini, Kiamaina and Bahati wards based on Yamane (1967)
formula. Primary data was collected through household surveys and secondary data on rainfall
and temperature for the past 30 years (1985 to 2015) was purposively sampled and collected
from Nakuru Meteorological Station. Maize yield data for Bahati Sub-County was collected
from the MOA, Tegemeo Institute and Nakuru County Agricultural Office for the period 1985
to 2015. The data collected on rainfall, temperature and maize yields was analyzed using
Microsoft Office Excel 2010 and SPSS software version 23 to generate frequency tables, pie
charts, graphs and moving averages. The findings were that annual rainfall and maize yield
have shown a decreasing trend, while the average annual, maximum and minimum temperature
have shown an increasing trend from 1985 to 2015. Rainfall has shown a decreasing trend
during the long rain season and an increasing trend during short rain season. Rainfall variability
is significant in both seasonal and annual trends with the highest annual rainfall variation below
average occurred in 2000 with a variation of 350.40mm and highest annual variation above
average occurred in 2010 with a variation of 475.80mm. The long rain season recorded the
highest rainfall variation below average in 2000 with a variation of 253.17mm and the highest
rainfall variation above average in 2010 with a variation of 263. 53mm.The Short rain season
recorded the highest rainfall variation below average in 1985 with a variation of 111.08mm and
the highest rainfall variation above average in 1997 with a variation of 247.31mm. Annual
average temperature has shown an increasing trend ranging from 17.7°C in 1989 to 19.7°C in
2009. Maximum temperature trend has shown a slightly gradual increase of 0.008°C annually.
Minimum temperature trend has shown a slightly gradual increase of 0.075°C annually. Annual
maize yield variability has shown a decreasing trend ranging from +11,913 Tonnes in 2000 to
+62,615 Tonnes in 1988 above average. The findings revealed that there is a significant,
positive and strong relationship between rainfall trend and maize yield (r= 0.741, p = 0.000).
The study also revealed that there is a significant, moderate and negative linear relationship
between maximum temperature and maize yield (r= -0.510, p= 0.03). However, the study
findings also revealed that the relationship between minimum temperature and maize yield had
an insignificant, weak and negative relationship (r= -0.166, p= 0.372). Eighty-six-point three
percent of the respondents from the opinion findings strongly agreed that climate variability has
influenced their annual maize yield levels in Bahati Sub-County. Sixty-four-point five percent
of the respondents disagreed that the adaptation strategies implemented have improved maize
yields in the area. The study suggested for further research to be done on maize varieties that
are tolerant to climate variability and on the best adaptation strategies of reducing maize
farmer’s vulnerability to climate variability. Also, Nakuru meteorological station should
provide forecast prediction to the farmers on the onset and cessation of the growing season so
as to help maize farmers plant and harvest on time.
Description
A Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Science (Climatology) in the School of Pure and Applied Sciences of Kenyatta University