Global Journal of Science Frontier Research, H: Environment & Earth Science, Volume 21 Issue 6

b) Trend in Yam Yield (Mt/Ha) in Nasarawa State Figure 1 shows the yam yield (Mt/Ha) trend in the state. The yam yield shows increasing trend in production over the periods under consideration from (2001-2015). From the result, the yearly yam yield shows an increase yield in 2010 and 2009, 21.69 and 21.56 respectively a slight drop of yield was recorded in the year 2002 of 14.52 (Mt/Ha). There was an increase in annual yam yield again in 2012 of 2015 (Mt/Ha) follow by a decrease in 2013. An increase in the quantity of yam yield was recorded in 2008, 2009, and 2010 respectively; there was a drop in yield of yam in 2011. Increase was recorded in the annual yam yield in Nasarawa state in 2012 of 20.46 (Mt/Ha). In the second decade, the amount of yam yield increase in 2012, then a steady yield of 19.46-19.51 which increase 2014 to 2015 with a slight variation between them. It is clear from the yam yield of Nasarawa state over the period (2001-2015), there was a steady increase, with 21.69 being the highest recorded trend of the annual yam yield, also shows a steady increase from 2007 (18.31), 2008 (20.21), 2009 (21.56) and 2010 (21.69). This means that the annual yam yield in Nasarawa state is gradual over the years in view. It may also mean that the high and favourable rainfall recorded, might be a reason for the increase of the yam yield in the study area. Figure 3: Yam Yield Mt/Ha Figure 4: Annual Minimum Temperature 0 5 10 15 20 25 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Yield (Mt/Ha) YEA… 0 5 10 15 20 25 30 TEMP. 0 C YEA… Analysis of Rainfall and Temperature Patterns on Yam Yield in Lafia, Nasarawa State, Nigeria © 2021 Global Journals 1 Global Journal of Science Frontier Research Volume XXI Issue VI Year 2021 38 ( H ) Version I