Trends and cycles of rainfall over Nigeria, as well as their implications for water resources and agriculture, have
been studied since 1960 on annual, seasonal and monthly bases. Rainfall data of 47 years (1960 – 2006) were
obtained for twenty stations over Nigeria for the evaluation of trends using the Mann-Kendall test. Auto
correlation spectral analysis was also used to detect cycles of rainfall. The result showed dominant peaks in
rainfall return at various rates. For instance, Akure, Benin, Calabar, Maiduguri and Yola stations had decreasing
trends of annual rainfall at rates of 1.084, 0.03, 1.80, 0.75, and 0.12 mm/month/yr, respectively with return
periods between 1-2 years and 7-10 years. Rainfall trends increased in about 75 % of the locations with return
period of dominant peaks varying between 1-2 years and 15 years. Abuja recorded the highest peak of rainfall
in the month of October at the rate of 4.7 mm/month/yr with return period of 1-2 years. These results indicate
different spatial effects on ecosystem and agriculture. Some of the implications of these trends on agriculture
and water resources vary from one station to another, depending on the trends and magnitude of return
period of rainfalls. Bauchi and Minna cities are expected to experience serious desertification and complete
depletion of underground water due to the effects of no change in trend of rainfall. Meanwhile, agricultural
activities are expected to thrive in places like Ibadan, Gusua, Osogbo and others that have moderate increase
in trends of rainfall and temperature.