Effect of Bone Char application in Reducing CO2 Emission and Improvement Organic Matter in Calcareous Soils

This study aims to identify the role of bone char (BC) application to calcareous soils in reducing CO2 emission and improving soil fertility compared to phosphate rock (PR). The bovine bone was subjected to anaerobic thermal decomposition (pyrolysis) for two hours at a temperature of 650 °C to produce bone char. Closed-system incubation experiments were conducted to follow the CO2 emission from the soil treated with BC or PR by rates 1.25 and 2.5%. CO2 emissions were tracked over 90 days at two different ambient temperatures (15+2 and 27+2oC). Results of the elemental composition of BC were similar to PR, but BC was characterized by the presence of organic carbon. The active surface groups of bone char are very similar to the phosphate rock groups, but the presence of organic matter resulted in the existence of C = C and O = C groups. A laboratory incubation experiment for 90 days was conducted for soil treated with bone char and tracking the emitted CO2. Application of BC to soil increased phosphorus solubility and retention of CO2 compared to phosphate rock (PR). Carbon dioxide (CO2) immobilization was very high in high temperature (27+2oC) reached 3274-3870 mg/kg soil compared to 101-242 mg/kg soil in low temperature (15+2 oC) in BC-treated soils. BC application to the soil in winter increased the organic carbon from 1.1 to 1.52%, while the percentage dropped from 0.79 to 0.55 in high temperature, with increasing of the dissolved organic carbon form by 40-60 mg/kg soil.