BACKGROUND : Biochar-based fertilizer delay the nutrient release and perform a slow release effect for agricultural and environmental advantages. This experiment was conducted to evaluate agro-environmental impacts and estimate soil carbon sequestration to different application rates of modified supplemented biochar pellets.
METHODS AND RESULTS : The treatments consisted of 1) the control, 2) 40% N, 3) 60% N and 4) 60% N (0.07M MgO) of modified supplemented biochar pellets (MSBP) which were based on 40% N, 60% N and 60% N of recommended rate of nitrogen and 60% N (0.07M MgO) reacted with major nutrient solution and 0.07M MgO for rice cultivation. For the paddy water, the NH4-N and NO3-N concentrations in whole treatments were rapidly increased at 84 days and 40 days after transplanting, respectively. The PO4-P concentrations were highest at 9 days after transplanting, and their concentrations in the MSBP were generally lower than those of the control. For the paddy soil, NH4-N concentrations in the MSBP were higher than those of the control at 5 days after transplanting, while NO3-N concentrations were not significantly different in the treatments through rice cultivation. P2O5 concentrations in the control were higher than those of the MSBP until 40 days after transplanting while K2O concentrations were not significantly different among the treatment. The highest carbon sequestration was 970 kg ha-1 in the 60% N 60%(0.07M MgO), and the potential carbon storage in the 60% N(0.07M MgO) was higher at 222 kg ha-1 than the control during rice cultivation. It shown that the rice yield in the control was not significantly different between the 40% N and 60% N(0.07M MgO) application plots.
CONCLUSIONS : Application of MSBP for rice cultivation was effective for carbon sequestration as well as agro-environmental impacts even though nitrogen application rate was reduced at 40% based on recommended application rate of fertilizer. Therefore the MSBP might be useful to apply for carbon sequestration and nitrogen reduction of fertilizer as well as mitigation of agro-environmental impacts.