Abstract:

The use of biochar as a soil amendment to enhance soil fertility and agricultural productivity is being explored. This study investigates the impact of using coal as biochar on the availability and dynamics of organic elements, as well as its effect on soil microbial activity. The experiment was conducted on ferralsols in Mahitsy, Antananarivo, Madagascar, during the 2024 bean-growing season. Coal was applied at rates of 25, 50, 75, 100, or 125 g per planting hole, along with organic fertilizers: bat guano (30 g) or manure (150 g). Samples were collected at the pod ripening stage (R8). The results showed that applying 50 g of coal per hole significantly increased the microbial population to 1.85×10⁵ colony-forming units (CFU)/g and boosted microbial activity to 3.1 µg fluorescein-H/g soil. These results suggest that using coal as biochar positively influences soil microbial dynamics and could enhance soil health and agricultural productivity.