Impact of rainfall variability and agricultural factors on maize yeild in Lusaka Province, 1976 to 2002

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Banda, Kamuna,Ackim
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There are many non climatic factors influencing the agricultural potential of an area, but of the climatic factors, the most important are the distribution in time and the amount of rainfall. The purpose of this study is to probe rainfall variability based on the persistence model which follows a theoretical distribution, and the theory of runs which requires that time series of rainfall data be considered as a success or failure about a selected truncation level. The overall objective of the study was to investigate the rainfall patterns, the agricultural factors, some drought run parameters and the frequency of their occurrence during the period 1976-2002 in relation to maize yields. The methodology included the use of probability sampling techniques, time series analysis, magnitude frequency analysis and the principal axis factor analysis in which 15 variables were correlated yielding six factors which were then orthogonally rotated and their factor matrices interpreted in terms of content of the variables that loaded most highly. The major findings were that there exists high rainfall variation within Lusaka Province whilst coefficients of variation show that Lusaka Province displays no evident trend. It has been established that it were wet spells in drought years that increased maize yields. Lusaka is prone to one-year droughts with the most severe droughts not being the most intense droughts. It has been discovered that before 1988 few factors influenced high maize yields whilst after 1989 the factors at interplay doubled causing Lusaka Province to plummet in rank in level of production. The conclusion was that there was an increase in the length of the growing season without a corresponding increase in maize yield due to the strong influence of the Southern Oscillation Index and Sea Surface Temperatures on rainfall variability. For purposes of implementing study results, recommendations were made. These included the need for an effective early warning unit, adapting farming to wet spells, improved input provision and marketing, and need for further research on individual agricultural factors. Application of study results should help farmers and agricultural officers in adopting the right kind of farming methods adapted to the changing environment and agricultural practices in the country
Rainfall intensity duration frequencies -- Zambia