Evaluation of carbon dynamics of calcareous soils amended with biochar under the application of low-voltage electrical charge

Among the important health parameters in soil, soil organic carbon (SOC), microbial biomass carbon (MBC), microbial respiration (CO₂), water-soluble carbon (WSC) are the most affected parameters by environmental conditions. In this study, we investigated the effect of low-voltage electrical charged soil (VEC: 0_mV - 3.5_mV - 7.5_mV) with biochar (BC) application on calcic Vertisol soil in terms of soil health parameters under laboratory conditions. At the end, 37-week measurement, the highest amount of soil CO₂-C emission was seen with a low-voltage electrical charged application of BC+7.5_mV (12.89 mg CO₂-C kg⁻¹ soil week⁻¹), while the lowest amount was seen with the application of BC+0_mV (1.31 mg CO₂-C kg⁻¹ soil week⁻¹). The Fourier transform infrared (FTIR) spectrum that displayed different functional group activities with all the application and the highest increases were observed in the alkyne (C-Br) (547 cm⁻¹) and alkenes (=C-H) (964 cm⁻¹) groups with BC application, while the lowest increases were seen with BC+7.5_mV application. Examining the thermogravimetric (TGA) results, the smallest mass loss was observed with the BC+7.5_mV application (24.98%), while the highest was with BC+3.5_mV (21.41%). The highest breakdown in differential scanning calorimeter (DSC) was observed in BC-applied soil in the volatile C group [(EXO 1 (30- 200 °C)]. Especially in EXO 3 (385–475 °C), a high level of breakdown occurred, which was an indication of recalcitrant carbon groups. This study indicated that low-voltage electrical pulse was inappropriate for evaluation of soil C dynamics including SOC, WSC, MBC, and basal soil respiration.