Nutrient Release from Mangrove Biochar in Brackish Water

Mangrove biochar residues from Samut Songkhram province were used for nutrient release in brackish water. The batch experiment studies of nutrient releases from biochar including nitrite, nitrate, ammonia and orthophosphate release in brackish water at salinity level of 30 ppt were compared with without salinity (0 ppt). The 1.25 g biochar was added in glass bottles containing 250 mL of brackish water. The bottles were placed in the incubator shaker at 100 rpm, 27 ^oC for 2, 4, 6, 8, 24, 48, 96, 144, and 240 hr. Results showed that the release of total inorganic-N at 30 ppt had higher release than at the salinity of 0 ppt. The released concentrations of inorganic-N at equlibrium were 0.209 and 0.623 mg-N/L for salinities at 0 and 30 ppt, respectively. However, the releases of ortho-phosphate were different as nutrient reached the equilibrium time at 240 hr, with the concentrations of 0.472 and 0.387 mg-N/L for salinities at 0 and 30 ppt, respectively. The nutrient releases from mangrove biochar in brackish water showed that the nutrient can be gradually released at 30 ppt and provide the N:P ratio higher than at 0 ppt. Therefore, the mangrove biochar can be used as a slow release ferilizer for aquaculture ponds, which is environmental friendly than chemical fertilizer.