Climate Variables and Their Impacts on Yield of Food Crops in Makwanpur and Ilam Districts of Nepal

Abstract

Climate change and variability is predicted to have negative impact mostly in countries which depend on rain-fed agriculture. This chapter intends to assess impact of climate variables on the yield of major food crops in two hilly districts: Makwanpur and Ilam of Nepal based on district-level time series data from 1978 to 2008. Trend analysis of climate variables shows that, in both Makwanpur and Ilam districts, temperature (minimum and maximum) is increasing both in summer and winter crop growing seasons with exception in Ilam district where minimum temperatures in both seasons are declining. Except for summer rainfall in Makwanpur, rainfall is decreasing in both the districts. This trend of climate variables tends to influence the yields of major food crops; paddy, wheat, maize, millet, barley and potato. The results of this study show that only minimum temperature has significant effect on yields of major food crops in Makwanpur. Marginal rise in minimum temperature reduces yields of paddy and maize but has no significant impact on yields of other crops in Makwanpur. Maximum temperature and rainfall tend to influence the yield trends of some major food crops in Ilam district. Higher maximum temperature tends to increase maize yield while rainfall tends to increase yields of paddy and wheat in Ilam district. Apart from paddy, the combined effect of climate variables indicates that yields of all other major crops are declining in Makwanpur. In Ilam, climate variables reduce the yields of paddy, wheat and millet while that of maize, potato and barley are increased.