Effects Of Rainfall Variability On Farming Activities In Machakos Sub County, Kenya

ABSTRACT

Varying climatic conditions with increased uncertainty mainly in rainfall and temperature are

salient features in marginal areas globally, adversely affecting farming activities particularly in

Africa. Kenya experiences variations of annual rainfall with considerable uncertainty. These

variations ranging from below 500mm to above 2000mm annually, cause droughts and floods

respectively, affecting farming activities and yields. This study focused on Machakos sub

County, a semi arid area, East of Central Kenya highlands. Information on the effects of rainfall

variability on farming activities in Machakos, have concentrated on small holder maize

cultivation and covered broad areas of the Eastern region and Machakos County, leaving out

other crops and livestock. They mainly cover the period between 1930 - 1990. After this period,

very scanty information exists. The main objective of the study was to investigate the influence

of rainfall variability on farming activities in Machakos sub County, focusing on Maize, Coffee

and Cattle farming. The specific objectives were to; establish the historical rainfall variability at

monthly, seasonal and annual basis in Machakos sub County between 1990 - 2014; determine the

human factors that influence rainfall variability in Machakos sub County and to assess the

relationship between rainfall variability and Coffee, Maize and Cattle Yields in Machakos sub

County. A cross sectional research design was used. A sample of 384 from 35,605 households

was drawn using the Webster (1995) formulae and stratified into units based on the twelve

locations. Primary data was collected through; household questionnaires, interviews, observation

and photographs. Publications from Meteorological Department Nairobi and sub county

Agricultural offices provided secondary data. Using SPSS, quantitative data was analyzed using

descriptive statistics such as Means, Standard deviation and percentages. Inferential statistics

using Pearson’s Correlation coefficient was used to determine relationships between variables.

Coefficient of variability, Relative variability and Precipitation Concentration index measured

Rainfall Variability. Qualitative data was analyzed through themes and patterns, conclusion and

generalization. The study established that monthly, seasonal and annual rainfall distribution in

Machakos sub County was highly variable, erratic and unpredictable over the 25 years with a CV

of 24% and a PCI of 10. Human activities influencing rainfall variability such as overgrazing and

deforestation were evidenced by high land carrying capacity, use of firewood and charcoal as the

main source of fuel and timber extraction. Correlation between annual rainfall totals and maize

yields (r = 0.632) and coffee yields (r = 0.695) were statistically significant at 0.05 significance

level. Maize and coffee yields increased with high rainfall. Cattle production showed a positive

relationship with the rainfall trends. There is high temporal rainfall variability (CV of 24% and

PCI of 10) in the sub County. Deforestation, overgrazing and over cropping are evident. Rainfall

variability has a strong relationship with Maize, Coffee and cattle farming and yields.

Disseminating information on rainfall forecasts, rainwater harvesting for irrigation, proper cattle

stocking, a forestation and reforestation programs were highly recommended.