Impacts of meteorological drivers and agricultural practices on sorghum, millet and sesame yields in semi-arid lands in Sudan

In sub-Saharan Africa rain-fed agriculture cropping system uses a limited agricultural technology, occupies more than 95% of cultivated land. The impact of meteorological drivers on crop yields, and, in addition, the effects of herbicide application on farm productivity were examined at two locations; with a 70km distance between them, El Mazmum and El Dali in semi-arid Sudan. For ten successive years (2001-2010), a time series of annual and monthly precipitation as well as the yields of sorghum, millet and sesame were analyzed. The Mann-Kendall test and Sen’s slope estimator methods were used to examine the significance and the slope of the trends in precipitation and yields. Analyses of variance (ANOVA and t-test) were used to establish the variation in crop yields. Annual precipitation during the ten-year period showed no significant trends at the two locations at 95% or 99% confidence levels. Sorghum and millet yields at one location showed significant declining trends at both 95% and 99% confidence levels. Linear regression indicated a clear positive correlation between residual (de-trended) precipitation and the yield of both sorghum at El Mazmum (R2 = 0.38) and the yield of sesame at El Dali (R2 = 0.49). Responses of crop yields to herbicide application showed insignificant differences as compared to non-herbicide-based cultivation. Results suggest that the variation in crop yields is mainly caused by the inter-annual variability of precipitation and inadequate farming practices.