Effects of Rainfall Variability on Subsistence Crop Production in Kahangara Division of Magu District, Tanzania

Abstract

ABSTRACT Rainfall variability is a major problem that affects subsistence crop production all over the world. African countries are most affected, because they are very much dependent on rain fed subsistence agriculture for their livelihood. Rainfall in Kahangara Division varies from time to time, of which between the years 2008 and 2010 experienced the decline of rainfall. This variability in rainfall may have had an impact on subsistence crop production. However, no documented study has so far shown the relationship. Therefore, the purpose of this study was to examine the effects of rainfall variability on subsistence crop production. The specific objectives of this study were to: assess the historical rainfall variability at annual, seasonal and monthly scales over the period between 1990 and 2010 in Kahangara Division; and to establish the effects of rainfall variability on subsistence crop production in Kahangara Division. Cross-sectional survey research design was used. The study targeted 4711 households of subsistence farmers and simple random sampling was used to select a sample size of 355 households. In addition, purposive sampling was used to obtain four agricultural extension officers and one meteorologist as key informants. Primary data was collected through questionnaires, interviews, direct observation and photography. Documentary review was used to collect secondary data from Magu weather stations and Kahangara Division Agricultural Office. Quantitative data was analyzed using descriptive statistics such as frequency distribution, percentages, means, standard deviations, coefficient of variation, inter-annual variability and correlation analysis. These data was processed using Statistical Package for Social Science (SPSS) and Instat software. Qualitative data was analyzed by creating themes and patterns then evaluating the usefulness of information in answering research questions. The empirical analysis of rainfall suggests there are high variabilities of annual, seasonal and monthly rainfall amounts over the last 21 years. The correlation between rainfall variability and sweet potatoes yields (r = 0.799, p< 0.01) and cassava yields (r = 0.586 p< 0.01) are statistically significant at 0.01, and sorghum yields (r = 0.426 p< 0.05) is statistically significant at 0.05 significant level. Therefore, it was concluded that there is high annual, seasonal and monthly rainfall variability .in Kahangara Division and it affects sweet potatoes, cassava and sorghum production. This study recommends that there should be an investment on future water supply to supplement rainfall through rain water harvest. Moreover, farmers are advised to grow different crop varieties and they should change the planting dates. Further, the meteorology department should disseminate information on rainfall forecast to farmers so as to make them aware of the effects of rainfall variability which may be helpful to farmers on decision making.