Temperature sensitivity of respiration in biochar-amended soils with different textures, moisture levels and fertilizer treatments

A b s t r a c t. Biochar additions change the temperature sensitivity (Q 10 ) of soil respiration.The aim of this study was to assess the effects of biochar on the Q 10 of CO 2 emissions from fertilized sandy and silty loam soils with different moisture contents.Soil samples fertilized with NPK and NPK+manure (NPK+M) were incubated at temperatures of 5 to 15°C, and 15 to 25°C, under 60 and 100% water holding capacity (WHC).Microbial biomass C, pH and soil organic C concentration were measured in soils with and without biochar.The mean Q 10 values varied from ~1 to 2 in most cases.The addition of biochar to silty loam affected the Q 10 in the NPK+M treatment after 24 h, and the Q 10 value increased from 0.90 to 1.36 at 5/15°C, while it decreased from 1.90 to 1.36 at 15/25°C.A similar effect of biochar was found with a sandy loam soil at 60% WHC.The lower Q 10 for CO 2 emissions after biochar application were particularly evident under higher temperatures and water saturated conditions.These results indicate that biochar can decrease the temperature sensitivity of native SOC mineralization and potentially enhance C sequestration in soils at higher temperatures.K e y w o r d s: biochar, Q 10 , soil respiration, fertilization, C sequestration, global warming