Trends and Spatial Patterns of Sorghum and Millet Production in the Northern Savannah Agro-climatic Zone of Ghana; A statistical Appraisal

Sorghum and Millet are the two most essential kinds of cereal, among many others, grown in the Northern Savannah Climatic Zone (NSAZ) of Ghana. The zone has climatic and ecological conditions which are well- suited to the cultivation of these crops. The high dependence on the two crops as major staples has ensured that they become essential crops whose production results in food security. However, output for these crops has suffered challenges emanating from unpredictable climatic conditions and high cost of inputs. This paper investigates and compares the level of productivity and rates of change for the two crops between the period 1960 and 2015 using the Mann-Kendall (MK) trend analysis. An assessment of the spatial dynamics that identifies areas of high production between the period 1992 and 2015 carried out using ordinary kriging interpolation. Sorghum production is at a much higher level of output with a maximum production level of 387,400 metric tonnes in the year 1997 compared to the maximum of Millet which is at 245,550 metric tonnes in the year 2008. The seasonal analysis reveals a very high increase in output for both crops for the period 1990 to 2010 (season 4) and the lowest season of production from 1970–1980 (season 2). Notably, the North-Eastern part of the Upper East region around the Bawku East, Bawku West and the Garu-Tempane districts are the areas with the highest levels of output which lies between latitudes 10° and 11°N which are the areas much drier. The general levels of productivity reveal that both crops have increased in output over the period of study, but Sorghum has seen a much higher rate of growth than Millet. The increase and decrease in production associated with a complimentary rise and reduction in Yield and Area harvested. The general spatial pattern of high Millet and Sorghum output and Yield varies over the entire Northern Savanah Agro-climatic Zone but with higher results recorded for the higher latitudes.