Trend analysis of productivity of some selected cereal crops in Nigeria: 1983-2008.

摘要

The study aimed at examining the trends of productivity of maize and sorghum in Nigeria between 1983 and 2008. Time series data in respect of annual yield (Kg/hectare) of the selected arable crops covering the period of study were obtained. Productivity was assessed using area harvested i.e. the quantity of crop produced per unit area harvested, given that yield growth rate remains the most commonly used indicator of productivity growth in a developing country’s agriculture. Trend analysis of the productivity of the crops was undertaken to determine changes across period of production. Trends of crops’ productivity were analyzed using graphical methods. Ratios and percentages were used to measure productivity (yield) growth rates of the selected crops of study. Data fitted on line graphs using Linear, Exponential, Polynomial and Logarithmic functional forms with trend lines created through the line graphs and extended over five (5) periods enabled quantitative analysis of the data and forecast. Polynomial function which gave the best fit in terms of the magnitude of the coefficient of determination (R2) was chosen and presented. Trend analyses show a stagnating and or declining growth rate for the crops of study while the current and future trends of productivity as depicted by the R2 values in respect of maize was strong at 0.678 and relatively weak for sorghum at 0.292. It is recommended that measures conducive for farmers to achieving stable yields for enhanced performance of crops in terms of productivity, pricing and marketability and expansion of cultivable land be adopted. Key Words: Productivity, Growth Rate, Functional Form, Analytical Trend, Coefficient of Determination.