Biochar is a Carbon-rich product derived from the slow pyrolysis of organic materials under oxygen limited conditions. It is usually used as a soil amendment to increase soil fertility, boost agricultural productivity, and provide protection against some foliar and soil-borne diseases.
Scientists have been studying biochar as an approach to carbon sequestration and thus help mitigate climate change via reducing soil greenhouse gas emission. However, a group of Chinese scientists recently found that during the freeze-thaw cycles period, biochar addition in soil may stimulate soil emission of carbon dioxide (CO2) while reduce that of methane (CH4).
Their study was published in the recent issue of Plant, Soil and Environment entitled “Effects of biochar addition on CO2 and CH4 emissions from a cultivated sandy loam soil during freeze-thaw cycles”.
Previous studies have shown that soil N2O emissions decreased by 61% during freeze-thaw cycles through biochar addition. But what will that do to the emission of Carbon dioxide and methane, two of the major greenhouse gases that play a key role in global climate change?
To answer this question, LI Lanhai and his team from the Xinjiang Institute of Ecology and Geography simulate the freeze-thaw cycles in their lab. They hope to examine the effects of biochar additions on soil carbon dioxide and methane emissions during freeze-thaw cycles.
Their study showed that soil CO2 emissions were stimulated by both freeze-thaw cycles and biochar addition. In the meantime, the biochar addition promoted the intake of CH4, especially under freeze-thaw conditions.
“Although there are some limitations in this study, the results still indicate that the effects of biochar additions on soil C emissions may be different between control and freeze-thaw conditions,” said LI.
More in-situ observations are expected in further studies to make systematic evaluations on the effects of biochar on greenhouse gas emissions during the freeze-thaw cycles, according to the researchers.