Comparison in Trend Analysis of Annual Rainfall Variability on Grain Yield Pattern in Gusau Station, Zamfara State, Nigeria

Abstract

Rainfall is a major determinant of agricultural production in any agro ecological zone like Gusau. Its seasonal and annual characteristics such as the  onset and  intra- seasonal   rainfall distribution that promote good crop yields are, however, characterized by marked fluctuations. This study compared 15 years (1996-2010) trend in annual rainfall variability on three grain crops yields (millet, sorghum and maize) in Zamfara State, Nigeria. Annual rainfall records for 15 years (1996–2010) for Gusau station were obtained from the Nigerian Meteorological Services Department, Lagos. Grain yield data for Millet, Sorghum and Maize from 1996-2010 were also obtained in kilogram per land hectare from the Zamfara State Agricultural Development Project (ZADP). The results of the various statistical tests were shown using graphs and statistical tables. The study revealed that both the five-year and ten-year moving averages for annual rainfall series showed lengthy and dry periods below the long-term mean from 1996-2001 with steady increases above the mean. In comparing the trends in the annual rainfall totals and pattern of grain yield within these periods, each grain yield pattern for the period was plotted in percentages against the years and it was observed that millet and sorghum were drought resistant because their values fell close or above normal indicating that they were able to cope with a decline in rainfall amount while maize was below normal. The Pearson’s Product Moment Correlation Coefficient and Pentad Sub-periodic Frequency of Significance at alpha= 0.05 also proved that millet and sorghum were positively correlated and appreciably significant to rainfall while maize was negative and insignificant except during the 3^rd period (2006-2010). The findings of this study concluded that millet and sorghum yields in the area have been economically appreciable and effectively able to cope with irregularities in rainfall attributes as low as 850 mm within the period. The study recommends that the research institutes should produce better adapted varieties of millet and other grains and government should subsidize the seeds to the farmers. Furthermore, there should be adequate provision for fertilizers, irrigation, weather forecasting and other agricultural technological infrastructure, modern knowledge on climate change adaptation and strengthening of the extension services.