Short-term effects of biochar on soil CO2 efflux in boreal Scots pine forests
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CitationZhu, Xudan. Zhu, Tingting. Pumpanen, Jukka. Palviainen, Marjo. Zhou, Xuan. Kulmala, Liisa. Bruckman, Viktor J. Köster, Egle. Köster, Kajar. Aaltonen, Heidi. Makita, Naoki. Wang, Yixiang. Berninger, Frank. (2020). Short-term effects of biochar on soil CO2 efflux in boreal Scots pine forests. Annals of forest science, 77 (2) , 59. 10.1007/s13595-020-00960-2.
Using biochar as a soil amendment has been proposed to increase the carbon sequestration in soils. However, a more rapid soil organic matter turnover after biochar application might reduce the effectiveness of biochar applications for carbon sequestration. By raising the pyrolysis temperature, biochar with lower contents of labile carbohydrates can be produced.
To better understand the effects of biochar on boreal forest soil, we applied two spruce biochar with different pyrolysis temperatures (500 °C and 650 °C) at amounts of 1.0 and 0.5 kg m−2 in a young xeric Scots pine forest in southern Finland.
Soil CO2, microbial biomass, and physiochemical properties were measured to track changes after biochar application during the first summer.
Soil CO2 increased 14.3% in 1.0 kg m−2 treatments and 4.6% in 0.5 kg m−2. Soil temperature and pH were obviously higher in the 1.0 kg m−2 treatments. Differences in soil CO2 among treatments disappear after correcting by soil temperature and soil moisture.
Biochar increased soil CO2 mainly by raising soil temperature in the short term. Higher biochar application rates led to higher soil CO2 effluxes. The increase in soil CO2 efflux may be transient. More studies are needed to get the optimum biochar amount for carbon sequestration in boreal forest.