Enhancing phytolith carbon sequestration in rice ecosystems through basalt powder amendment

Global warming as a result of rapid increase in atmospheric CO2 emission is significantly influencing world's economy and human activities. Carbon sequestration in phytoliths is regarded as a highly stable carbon sink mechanism in terrestrial ecosystems to mitigate climate change. However, the response of plant phytolith-occluded carbon (PhytOC) to external silicon amendments remains unclear. In this study, we investigated the effects of basalt powder (BP) amendment on phytolith carbon sequestration in rice (Oryza sativa), a high-PhytOC accumulator. The results showed that the contents of phytolith and PhytOC in rice increased with BP amendment. The PhytOC production flux in different rice plant parts varied considerably (0.005-0.041 Mg CO2 ha(-1) a(-1)), with the highest flux in the sheath. BP amendment can significantly enhance flux of phytolith carbon sequestration in croplands by 150 %. If the global rice cultivation of 1.55 x 10(8) ha had a similar flux of PhytOC production in this study, 0.61 x 10(7) to 1.54 x 10(7) Mg CO2 would be occluded annually within global rice phytoliths. These findings highlight that external silicon amendment such as BP amendment represents an effective potential management tool to increase long-term biogeochemical carbon sequestration in crops such as rice and may also be an efficient way to mitigate the global warming indirectly.