Growth rate and doubling time of yam and cassava production in Nigeria

The growth rate and doubling time of yam and cassava output, yield and acreage was investigated from data obtained from a secondary source and analyzed using the exponential and quadratic function in trend variable. The study revealed the growth rate during the period under consideration, there were growth as well as retardation, and it also shows acceleration, stagnation and deceleration at different sub-periods for the variables. Average growth rate of 6.7% for yam hectares, 0.03% for yam yield and 7.2% for yam output, translating into doubling time of 10 years for yam hectare, -0.8 year for yam yield and 62 years for yam output were estimated. The average rate of growth for cassava hectare was 11.1%, -0.498% for cassava yield and 8.5% for output. This translates to doubling time of 1 year for cassava hectare,-0.5 year for cassava yield and 14 years for output. This study also revealed that the growth rates of yam and cassava production over the years have more of stagnation than acceleration and deceleration based on the changes in the macroeconomic policy of the country, which implies that planning of the macroeconomic policies were not better than the previous ones. It therefore, indicates that, although there has been some level of increase in some of the sub-periods, the policy presentation for yam and cassava did not in any way translate to sustained increase.