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 (CH) 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 CH emission were related to the soil moistures, with reduction of CH emission at 35 and 60 % WFPS and stimulation at the highest soil moisture. While both soils changed from CH sinks to sources by increasing soil moisture regardless of biochar addition, the effect was enhanced with biochar application. At lower soil moistures, the CH oxidation activity in soils was higher with biochar than without biochar, while the trend became opposite at higher soil moistures. Therefore, the CH production and consumption processes were influenced by different soil moisture levels and microbial communities of different soils. [ABSTRACT FROM AUTHOR]