Effects of biochar application on soil methane emission at different soil moisture levels

The aim of this study was to investigate the effects of biochar application on soil methane (CH₄) emission. Experiments were conducted over an 84-day incubation period with the following treatments: each of two soils (a paddy soil and a forest soil) was treated with or without biochar at three soil moisture levels (35, 60, and 100 % water-filled pore space (WFPS) for the paddy soil; 35, 60, and 85 % WFPS for the forest soil). Biochar application (P < 0. 05) significantly increased soil pH and stimulated C mineralization at the early incubation stage. The effects of biochar application on CH₄ emission were related to the soil moistures, with reduction of CH₄ emission at 35 and 60 % WFPS and stimulation at the highest soil moisture. While both soils changed from CH₄ sinks to sources by increasing soil moisture regardless of biochar addition, the effect was enhanced with biochar application. At lower soil moistures, the CH₄ oxidation activity in soils was higher with biochar than without biochar, while the trend became opposite at higher soil moistures. Therefore, the CH₄ production and consumption processes were influenced by different soil moisture levels and microbial communities of different soils.