Evaluation of chemical changes of plant residues in biochar and its effects on microbial respiration of two acidic and calcareous soils

Biochar is a carbon-rich solid produced via the thermal decomposition of plant biomass under anoxic conditions. It can be used as a modifier to improve soil chemical properties in soils with poor soil conditions and to enhance soil fertility through increasing soil organic carbon storage. On the other hand, biochar is a long-term mechanism for carbon sequestration in poor organic matter soils. It can affect soil chemical properties such as cation exchange capacity (CEC), acidity and nutrient concentration. The effect of three types of biochar prepared from beech residues, rice bran and pistachio shell on soil chemical properties were evaluated in this study. The biochars were obtained by heating various plant residues at 400 °C for 120 min under low oxygen conditions. Chemical decomposition results revealed that carbon and phosphorus concentrations increased as a result of conversion of plant residues to biochar, but nitrogen and hydrogen concentrations decreased. The results also showed that biochar has a significant effect on soil microbial respiration.