This incubation study assessed the effects of unpyrolyzed Calotropis procera and its biochar produced at different
pyrolysis temperatures as well as incubation periods on carbon (C) emission, ammonia (NH3) volatilization, soil
quality indicators and nutrient availability of alkaline sandy soil. Five treatments were studied in this experiment:
unamended soil (CK), unpyrolyzed calotropis (UPC), calotropis biochar at 250 °C (CB250), calotropis biochar at
400 °C (CB400), and calotropis biochar at 650 °C (CB650). These amendments were applied to the soil at level
of 4% (w/w). The results of this study showed that applying unpyrolyzed calotropis residues increased cumulative
CO2 emission from the soil by 117.3, 239.4 and 232.0% over CB250, CB400, and CB650, respectively, by the end of
incubation. Compared to the unamended soil, applying CB250 reduced cumulative NH3 volatilization in soil by
71.5%, which attributed to ammonia adsorption because of increased cation exchange capacity and decreased
soil pH, but CB650 increased cumulative NH3 volatilization by 73.3% after the 3-day incubation as a result of
high soil pH. The available phosphorus in soil improved significantly (p ≤ 0.01) with adding unpyrolyzed
calotropis residues and its biochar produced at different pyrolysis temperatures compared to the unamended
soil. The values of available phosphorus in the soil under study influenced significantly by pyrolysis temperatures
of produced biochar; this is due to the pyrolysis of feedstocks increases labile phosphorus. Thenceforth, using biochar is an important strategy for enhancing carbon sequestration, decreasing ammonia volatilization and improving soil quality parameters in arid regions.