Int. J. Environ. Eng. Nat. Resour. Volume 1, Number 1, 2014, pp. 53-60 Received: May 25, 2014; Published: July 30, 2014 International Journal of Environmental Engineering and Natural Resources Effect of Some Weather Parameters on Maize Yield in Ibadan, Southwest, Nigeria Kamba John 1 and Ajayi Vincent Olanrewaju 2 1. Nigerian Meteorological Agency, Bill Clinton drive, Nnamdi Azikiwe International Airport Road, Abuja 2. Department of Meteorology, Federal University of Technology, PMB 704, Akure 340001, Nigeria Corresponding author: Ajayi Vincent Olanrewaju (voajayi@futa.edu.ng) Abstract: Weather parameters have been studied to imply significant impact on Maize in the study area. In this study, records of crop yields and some weather variables for a decade (2001-2010) were used to carry out a comprehensive study on the effect of some weather parameters on Maize yield in Ibadan. The climatic variables were computed from daily means into three different phase of growing season (MAM, JJA and JAS) growing season. Also employed is the Z-transformation of the annual yield anomaly data for Maize crop was indexed to show varying significance of annual effect of weather parameters on crop yield. Also correlation and regression analysis were used to analyze the effect of weather parameters on Maize yield. The correlations between maize yields were performed for annual, MAM, JJA and JAS to ascertain the season when weather parameter affect annual crop yield. The MAM season welded strongest influence on the annual crop yield while JAS which is the secondary planting season also has effect on the yield. The weather parameter with correlation coefficients from 0.5 and above was regressed using multi-linear regression at 95% confidence level to derive the Crop-climate prediction model. The results of this study showed that crop yields, maximum and minimum temperature, relative humidity, number of rain day and amount of rain fall varied significantly from year to year and from season to season. There was a significant relationship between crop yields, rain fall variability and temperature in the study area. Key words: Temperature, rainfall variability, Z-transformation, Crop-climate prediction models, correlation coefficients. 1. Introduction Nigeria is an agrarian country, because about 70% of the population engages in agricultural production at a subsistence level despite the fact that the country depends heavily on the oil industry for its budgetary revenues [1]. Agricultural holdings are generally small and scattered. Traditional smallholders, who use simple techniques of production and the bush-fallow system of cultivation, account for around two-thirds of Nigeria's total agricultural production. Nigeria's wide range of climate variation allows it to produce a wide variety of food and cash crops. However, food production could not keep pace with population increase. Food shortage is therefore linked with climate change [2]. Agricultural production in Nigeria is weather dependent. Extreme variations in rainfall, temperature and heat waves affect food production. Droughts, floods, and tropical rainstorms create food scarcity problems and mass movement/immigration of people. The Intergovernmental Panel on Climate Change (IPCC) defined Climate change as a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Drought is one of the side effects of climate change and variability which Akeh et al. [3] defined as a creeping phenomenon, characterized by extended period with rainfall below average, prolonged periods of dryness, high temperature and evapo-transpiration, very low humidity, and reduced soil moisture that affects crop physiology and field capacity water. WMO [4] also revealed that global rising temperature now estimated to be 0.2 ºC per decade or 1 ºC by 2040