Biogeochemical silicon cycle and carbon sequestration in agricultural ecosystems

Global agricultural ecosystems, the largest biospheric sources of atmospheric carbon dioxide (CO2), may turn into considerable net carbon (C) sinks through adopting management strategies advised by research. As C sequestration is usually coupled with the silicon (Si) cycle, strategic manipulation of the biogeochemical Si cycle in agricultural ecosystems offers a not yet fully explored possibility to enhance C sequestration. This review summarizes current knowledge of C sequestration coupled with the Si cycle and its management in agricultural ecosystems. Carbon sequestration is coupled with the Si cycle through many processes including dynamics of phytoliths and aggregates, and silicate weathering at different temporal and spatial scales. Cultivation of deep rooting crops, erosion mitigation with buffer strips, fertilization of Si-rich materials are some of the potential management strategies to increase both crop production and C sequestration coupled with the Si cycle. Further questions such as identifying the controlling factors of bioavailable Si pools and C sequestration, and quantifying the cost-efficiency of different management strategies to manipulate the Si cycle with the aim to enhance C sequestration should be investigated.