Abstract
This study evaluated root and tuber crops yield under the changing climatic conditions in Kwara State, located in the Guinea savannah Zone of Nigeria. Rainfall data (1975-2014), minimum and maximum temperature (1985-2014) and yield data of cassava and yam covering a period of twenty years (1995-2014) were used for the assessment. A questionnaire was administered to a sample of 150 tuber crops farmers in twelve villages from Ilorin East, Asa and Moro Local Government Areas of Kwara State. The questionnaire was formulated to collect information on farmers Socio-economic characteristics, awareness and Perception of climate change and the various adaptation strategies been used. Trend analysis and standardized anomaly were performed on rainfall and temperature. Modified Walter’s method was used to determine rainfall onset, cessation and length of raining season. Co-integration and Error correction model test were the analytical tools employed in the analysis of effect of climate on cassava and yam yield. The results shows that, there is an increased in annual rainfall of about 3.5mm/year from 1975 to 2014. Minimum and maximum temperature from 1985 to 2014 have also statistically increased at 95% confidence level with minimum temperature increasing at a faster rate compared to maximum temperature. In addition, the analysis of daily rainfall data showed that, on the average, the onset and cessation dates were 30th March and 12th October, depicting both an early onset and cessation of rainfall leading to a decrease in length of raining season. The results obtained from Co-integration and Error correction model test indicate that there is a long-run relationships between the crop yield and annual rainfall, temperature and length of raining season. The output of yam was found to have a significant positive relationship with a coefficient of 0.00041 with the amount of rainfall. This shows that the production of yam irrespective of their increasing output was still dependent on the amount of rainfall. However, there was a negative relationship between cassava yield and rainfall though was not significant but temperature and length of raining season were significant in cassava model. Hence, increase in temperature and shortening of length of raining season will adversely affect the yield of cassava. The socio-economic survey revealed that majority of the respondents (91.3%) are aware of climate change with more than 92% of farmers indicating that temperature in the area had increased and about 56.2% of the respondents indicating that rainfall has also been on the increase. Moreover, the average adaptive capacity of the respondent was moderate (2.92), but majority of the respondents were highly adaptive to some individual adaptation strategies which are positively reflecting the trend of tuber crop yield in the area which shows an increasing trend. In conclusion, although there is a gradual decreasing in length of raining season over the last forty years, however, Kwara State is becoming wetter especially from 2003 to 2014.