Nutrient uptake and productivity of four tropical cropping systems under biochar amendment

Integrated measures including climate‐smart options have been proposed to improve crop production in sub‐Saharan Africa. However, there are limited studies exploiting biochar (BC) use under different cropping systems in the region. We evaluated nutrient uptake, grain and biomass yields, and economic viabilities of integrated use of BC under cereal‐ and legume‐based cropping systems in Ghana. The two‐factor field experiment was conducted in three consecutive cropping seasons and comprised soil amendments (BC, NPK fertilizers, 50% NPK + 50% BC, and control) and cropping systems (sole maize [ Zea mays ], maize intercropped with soybean [ Glycine max (L.) Merr.], sole soybean and cowpea [ Vigna unguiculata L.]). Generally, sole application of mineral fertilizers increased ( p  < .05) maize grain yield more than the 50% NPK+50% BC. Conversely, the 50% NPK + 50% BC generally produced similar yields ( p  > .05) of cowpea and soybean as the sole application of the 100% recommended NPK rates. For maize biomass yield, 50% NPK + 50% BC generally outperformed the sole NPK and sole BC treatments. Nutrient uptake in maize was higher in sole NPK and the integrated plots under sole cropping than in intercropping system. Nitrogen uptake of maize in 50% NPK + 50% BC was 12–22% higher in sole cropping than in intercropping system. The value/cost ratio under NPK was above the economic threshold (>2.0) under cropping systems. For 50% NPK + 50% BC, the economic threshold was only exceeded under intercropping cropping system, indicating a considerable intercropping benefits in integrated biochar and mineral fertilizer application.