Precipitation Effectiveness and Yam Production in Kwara State, Nigeria

Abstract

Insufficiency  in  the  production  of  food  crops  in  Nigeria  has  been  linked  with  variation  in  rainfall  features.  This  paper  examined  the  impacts  of  variation in rainfall onsets, cessations and length of growing season on yam yield  in  Kwara  State,  Nigeria  to  proffer  a  solution  to  the  problem  of  food  insecurity in the state. Rainfall data were collected monthly for six stations in  Kwara  State  between  1961-2017  (57  years).  Yam  yield  data  were  also  collected  for  the  same  period.  Since  no  separate  record  of  yam  is  kept  for  each climatic station, mean climatic data were calculated to match the yam yield record obtained from the above stations. Rainfall onset, cessation and Length  of  Growing  Season  (LGS)  were  calculated  from  monthly  values.  Decadal  partitioning  of  both  the  crop  and  rainfall  features  was  made  to  show  variations.  Time  series  analysis  was  employed  to  study  trends.  The  strength  of  the  relationship  between  the  length  of  the  growing  season  and  yam  yield  was  also  conducted  using  correlation  analysis.  The  result  showed  an  upward  trend  of  onset  of  rain  coupled  with  a  downward  trend  in late cessation of rain and a decline in the length of the growing season. On a decadal basis, increasing frequency of delayed onset of rain and late cessation was observed. Length of growing season exhibits a positive (r = 0.455**)  relationship  with  yam  yield.  Suggestions  were  made  on  how  to  attain sustainable efficient yam cropping in the study area.