Use of biochar in enhancing crop yields and its nutrient depletion over time

Faecal sludge biochar, produced through pyrolysis, offers a dual solution to food insecurity in Africa and climate change by enhancing crop yields as a soil amendment while enabling carbon sequestration. This study investigated the effects of Rocket Astra (Eruca vesicaria subsp. sativa) on crop productivity and nutrient depletion over time, grown in sandy, acidic soil. Four treatments were compared: biochar alone, fertilizer alone, biochar plus fertilizer, and an untreated control. The biochar–fertilizer combination produced the highest yields for most parameters, except root length, where biochar alone excelled. Biochar alone outperformed fertilizer in overall yield, while the control group had the lowest productivity. The combination treatment also significantly reduced water runoff. However, results across growing cycles revealed marked nutrient depletion in cycle two, with declines in shoot and root biomass and increased water runoff. These findings underscore biochar’s potential for sustainable agriculture in sub-Saharan Africa, while highlighting the importance of addressing nutrient loss over time and implementing policies to support farmer adoption and knowledge dissemination.