Enhancing phytolith carbon sequestration in rice ecosystems through basalt powder amendment

Global warming as a result of rapid increase in atmospheric COa emission is significantly influencing world＇s economy and human activities. Carbon sequestra- tion 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 produc- tion flux in different rice plant parts varied considerably （0.005-0.041 Mg CO_2 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 × 10^8 ha had a similar flux of PhytOC production in this study, 0.61× 10^7 to 1.54 × 10^7 Mg CO_2 would be occluded annually within global rice phytoliths. These findings highlight that exter- nal 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.

Phytolith carbon sequestration in bamboos of different ecotypes:a case study in China

Occlusion of carbon(C) within phytoliths(Phyt OC) is becoming one of the most promising terrestrial C sequestration mechanisms. This study explored the production of Phyt OC within 35 bamboo species belonging to three ecotypes using methods of microwave digestion. The aim of this study is to explore the present and potential C sequestration rate within phytoliths of bamboo species from three ecotypes. Phyt OC content in bamboos of three ecotypes ranges from 0.07 % to 0.42 %. The mean Phyt OC production flux decreases as: clustered bamboo(0.050 ±0.016 t CO2ha-1a-1) & mixed bamboo(0.049 ± 0.016 t CO2ha-1a-1) [ scattered bamboo(0.038 ± 0.020 t CO2ha-1a-1). The phytolith carbon sequestration in Chinese bamboo is estimated to be 0.293 ± 0.127 Tg(1 Tg =1012g) CO2a-1; approximately 75 %, 3 %, and 22 % of which is contributed from scattered, mixed and clustered bamboo, respectively. Taking the Phyt OC production flux of 0.18 ± 0.12 t CO2ha-1a-1and current annual area increasing rate of 3 %, global bamboo phytoliths wouldsequester 11.9 ± 7.9 Tg CO2a-1by 2050. Consequently,bamboo forests have significant potential to mitigate the increasing concentration of atmospheric CO2 by maximizing Phyt OC production flux and expanding bamboos.