The effects of woodchip biochar application on crop yield, carbon sequestration and greenhouse gas emissions from soils planted with rice or leaf beet

Pot experiments were performed to examine the effects of biochar application on crop growth and yield, soil properties, soil carbon sequestration, and greenhouse gas emissions from soil. The biochars were produced by the pyrolysis of woodchips from Japanese Cedar thinned from plantation trees. Two biochars were investigated; one produced at 290 °C (BC290), the other at 700 °C (BC700). Characteristic soils from Taiwan, namely the acidic Pinchen series (Pc) and the alkaline Hoshin series (Hb) were selected for the investigation. The different biochars (BC290 or BC700) were applied at two different rates, either 2% or 5% and the soils planted with either rice or leaf beet. The results showed that the application of biochar increased the soil pH and the available K, but had no significant effect on crop growth and yield. The application of 5% BC700 produced the most significant carbon sequestration with both rice and leaf beet. The application of 5% BC700 also significantly reduced the cumulative CO2e emissions from both the Pc (52%) and Hb (46%) soils planted with rice, while the application of 2% BC700 significantly reduced the cumulative CO2e emission from the Pc soil (47-58%), but not consistently from the Hb soil planted with leaf beet. Results of this study suggested that the application of biochar from waste wood was a perspective option to reduce greenhouse gases (as N2O or CO2e) emitting from fertilized soils and to enhance soil properties (as pH, available K).