Tillage, sole and intercrop systems and soil amendment influence on sorghum grain and stover nutrient levels

Sorghum [Sorghum bicolor (L) Moench) is a major grain crop in Burkina Faso. A three-year experiment was conducted in the Sudanian zone to determine the combined effects of tillage methods (T) and cropping systems with different soil amendments (CS/SA) on plant nutrient concentrations and related this to human and cattle nutrient requirements. The analysis of variance indicated that tillage, soil amendment nor cropping system affected the stover nutrient concentration of grain sorghum. Nitrogen, P, K, S, Ca, Mg, Zn, Mn and Cu concentrations in grain were all influenced by the Y x T interaction largely due to increased nutrient concentrations for no-till in 2012 and tied ridges in 2013. As grain yield increased, grain N, Ca, Mg and Mn concentrations decreased while P and Zn increased. Grain N, P, Mg, S, Fe and Zn concentrations met human nutritional requirements, while K, Ca, Mn and Cu were deficient and merited supplementation. Nutrient gross means indicated that cattle nutrient requirements were met for N, P, Mg, Fe and Zn, but low for K, Ca, S, Mn and Cu. Tillage, CS/SA and Y had no or small effects on the nutrient concentrations of sorghum grain and stover. The agroecological zones in 2012 and 2013 indicated most nutrients to be adequate for human and cattle diets, but not for K, Ca, Mn and Cu.