Effect of climate variability on yields of selected staple food crops in northern Ghana

Agriculture in Ghana is vulnerable to the adverse effects of climate variability. This poses a challenge to food security across the country. Despite this vulnerability, limited research has been conducted to understand the effect of climate variability on the yields of staple food crops in Ghana. This study assessed the effect of climate variability on the yields of selected staple food crops (millet, sorghum, rice, groundnut and maize). The study used the Mann-Kendall trend test and multiple regression analysis to assess how climate variability (in annual rainfall, onset, cessation, number of dry days and temperature) has affected the yields of selected food crops in five districts in northern Ghana (Bole, Nanton, Tolon, Kassena Nankana East and Wa) over a 21-year period (1995–2016). Results suggested a marginal decrease in annual rainfall (p > 0.05) and a significant increase in temperature (p < 0.05) over the period of study in the districts. Variability in the onset, cessation, length of rainy days and number of dry days was statistically significant from year to year, and also across the districts (p < 0.05). Results indicated substantial variability in the yields of the selected staple food crops. Temperature, number of dry days, onset, annual rainfall and cessation explained about 43%, 32%, 30%, 25% and 14%, respectively of the variations in the yields of groundnut, sorghum, millet, maize and rice. Our results generally suggest that the changing climate substantially affects food production in the study districts, highlighting the need for adaptations including the use of agricultural diversification and the greater use of drought tolerant varieties of these staple crops, as well as the continuing investment in crop breeding programmes to enhance drought tolerance.