Carbon sequestration within millet phytoliths from dry-farming of crops in China


Phytoliths are noncrystalline minerals that form inside cells and cell walls of different parts of plants. Organic carbon in living cells can be occluded in phytoliths during plant growth. It has been documented that the occluded carbon within phytoliths is an important long-term terrestrial carbon reservoir that has a major role in the global carbon cycle. Common millet and foxtail millet have become typical dry-farming crops in China since the Neolithic Age. The study of carbon conservation within phytoliths in these crops could provide insights into anthropogenic influences on the carbon cycle. In this study, we analyzed the carbon content in phytoliths of common millet and foxtail millet. The results indicated that (1) common millet and foxtail millet contained 0.136% ± 0.070% and 0.129%± 0.085% phytolith-occluded carbon (PhytOC) on a dry mass basis, respectively; (2) based on the mean annual production of common millet and foxtail millet in the last 10 years, the phytolith occluded carbon accumulation rate of common millet and foxtail millet was approximately 0.023 ± 0.015 and 0.020± 0.010 t CO2 ha−1 a−1, respectively; (3) assuming a similar phytolith occluded carbon accumulation rate as for common millet (the highest accumulation rate was 0.038 t CO2 ha−1 a−1), this could result in the sequestration of 2.37 × 106 t CO2 per year for the 62.4 × 106 ha dry-farming crops in China. Although there was a decline in the annual production rate and planting area of foxtail millet during 1949 to 2008, the total phytolith carbon sequestration rate was 7×106 t CO2 within the 60-year period. However, phytolith occluded carbon has not yet been fully considered as a global carbon sink. Also, this carbon fraction is probably one of the best candidates for the missing carbon sink.


  1. 1

    Falkowski P, Scholes R J, Boyle E, et al. The global carbon cycle: A test of our knowledge of earth as a system. Science, 2000, 290: 291–296

    Article  Google Scholar 

  2. 2

    Schimel D. Terrestrial ecosystems and the carbon cycle. Glob Change Biol, 1995, 1: 77–91

    Article  Google Scholar 

  3. 3

    Kosten S, Roland F, Da Motta Marques D M L, et al. Climate-dependent CO2 emissions from lakes. Glob Biogeochem Cycles, 2010, 24: GB2007

    Article  Google Scholar 

  4. 4

    Post W, Peng T, Emanuel W, et al. The global carbon cycle. Amer Sci, 1990, 78: 310–326

    Google Scholar 

  5. 5

    Gifford R. The global carbon cycle: A viewpoint on the missing sink. Funct Plant Biol, 1994, 21: 1–15

    Google Scholar 

  6. 6

    Houghton R A, Davidson E A, Woodwell G M. Missing sinks, feedbacks, and understanding the role of terrestrial ecosystems in the global carbon balance. Glob Biogeochem Cycles, 1998, 12: 25–34

    Article  Google Scholar 

  7. 7

    Field C B. Plant physiology of the “Missing” carbon sink. Plant Physiol, 2001, 125: 25–28

    Article  Google Scholar 

  8. 8

    Clark D A. Are tropical forests an important carbon sink? Reanalysis of the long-term plot data. Ecol Appl, 2002, 12: 3–7

    Article  Google Scholar 

  9. 9

    Pacala S W, Hurtt G C, Baker D, et al. Consistent land- and atmosphere-based U.S. carbon sink estimates. Science, 2001, 292: 2316–2320

    Article  Google Scholar 

  10. 10

    Siegenthaler U, Sarmiento J L. Atmospheric carbon dioxide and the ocean. Nature, 1993, 365: 119–125

    Article  Google Scholar 

  11. 11

    Fang J Y, Guo Z D. Looking for missing carbon sinks from terrestrial ecosystem (in Chinese). Chin J Nat, 2007, 29: 1–6

    Google Scholar 

  12. 12

    Harrison K, Broecker W, Bonani G. A strategy for estimating the impact of CO2 fertilization on soil carbon storage. Glob Biogeochem Cycles, 1993, 7: 69–80

    Article  Google Scholar 

  13. 13

    Fang J Y, Piao S L, Zhao S Q. The carbon sink:the role of the middle and high attitudes terrestrial ecosystem in the Northern Hemisphere (in Chinese). Acta Phytoecol Sin, 2001, 25: 594–602

    Google Scholar 

  14. 14

    Rovner I. Plant opal phytolith analysis: Major advances in archaeobotanical research. In: Schiffer M B, ed. Advances in Archaeological Method and Theory Vol.6. New York: Academic Press, 1983. 225–266

    Google Scholar 

  15. 15

    Piperno D. Phytoliths: A Comprehensive Guide for Archaeologists and Paleoecologists. London: Altamira Press, 2006. 5–21

    Google Scholar 

  16. 16

    Parr J F, Sullivan L A. Soil carbon sequestration in phytoliths. Soil Biol Biochem, 2005, 37: 117–124

    Article  Google Scholar 

  17. 17

    Strömberg C. Using phytolith assemblages to reconstruct the origin and spread of grass-dominated habitats in the great plains of North America during the late Eocene to early Miocene. Paleogeogr Paleoclimatol Paleoecol, 2004, 207: 239–275

    Article  Google Scholar 

  18. 18

    Prasad V, Strömberg C, Alimohammadian H, et al. Dinosaur coprolites and the early evolution of grasses and grazers. Science, 2005, 310: 1177

    Article  Google Scholar 

  19. 19

    Parr J, Sullivan L, Chen B, et al. Carbon bio-sequestration within the phytoliths of economic bamboo species. Glob Change Biol, 2010, 16: 2661–2667

    Article  Google Scholar 

  20. 20

    Grace J. Understanding and managing the global carbon cycle. J Ecol, 2004, 92: 189–202

    Article  Google Scholar 

  21. 21

    Oldenburg C M, Torn M S, DeAngelis K M, et al. Biologically enhanced carbon sequestration: Research needs and opportunities. Report on the Energy Biosciences Institute Workshop on Biologically Enhanced Carbon Sequestration, 2008

  22. 22

    Jones R L, Beavers A H. Aspects of catenary and depth distribution of opal phytoliths in Illinois soils. Soil Sci Soc Amer J, 1964, 28: 413–416

    Article  Google Scholar 

  23. 23

    Wilding L P, Brown R E, Holowaychuk N. Accessibility and properties of occluded carbon in biogenetic opal. Soil Sci, 1967, 103: 56–61

    Article  Google Scholar 

  24. 24

    Mulholland S, Prior C. AMS radiocarbon dating of phytoliths. MASCA Res Pap Sci Archaeol, 1993, 10: 21–23

    Google Scholar 

  25. 25

    Smith F, Anderson K, Meunier J, et al. Characterization of organic compounds in phytoliths: Improving the resolving power of phytolith δ 13C as a tool for paleoecological reconstruction of C3 and C4 grasses. In: Meunier J D, Colin F, eds. Phytoliths: Applications in Earth Sciences and Hunman History. Netherlands: A.A. Balkema, 2001. 317–327

    Google Scholar 

  26. 26

    Carter J A. Phytolith analysis and paleoenvironmental reconstruction from Lake Poukawa Core, Hawkes Bay, New Zealand. Glob Planet Change, 2002, 33: 257–267

    Article  Google Scholar 

  27. 27

    Lu H Y, Wu N Q, Yang X D, et al. Phytoliths as quantitative indicators for the reconstruction of past environmental conditions in China I: Phytolith-based transfer functions. Quat Sci Rev, 2006, 25: 945–959

    Article  Google Scholar 

  28. 28

    Bremond L, Alexandre A, Wooller M J, et al. Phytolith indices as proxies of grass subfamilies on East African tropical mountains. Glob Planet Change, 2008, 61: 209–224

    Article  Google Scholar 

  29. 29

    Ge Y, Jie D M, Guo J X, et al. Response of phytoliths in Leymus chinensis to the simulation of elevated global CO2 concentrations in Songnen Grassland, China. Chinese Sci Bull, 2010, 55: 3703–3708

    Article  Google Scholar 

  30. 30

    Lu H, Zhang J, Wu N, et al. Phytoliths Analysis for the discrimination of Foxtail Millet (Setaria italica) and Common Millet (Panicum miliaceum). PLoS ONE, 2009, 4: e4448

    Article  Google Scholar 

  31. 31

    Ranere A J, Piperno D R, Holst I, et al. The cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexico. Proc Natl Acad Sci USA, 2009, 106: 5014–5018

    Article  Google Scholar 

  32. 32

    Li X Q, Zhou X Y, Zhang H B, et al. The record of cultivated rice from archaeobiological evidence in northwestern China 5000 years ago. Chinese Sci Bull, 2007, 52: 1372–1378

    Article  Google Scholar 

  33. 33

    Kelly E F, Amundson R G, Marino B D, et al. Stable isotope ratios of carbon in phytoliths as a quantitative method of monitoring vegetation and climate change. Quat Res, 1991, 35: 222–233

    Article  Google Scholar 

  34. 34

    Krull E S, Skjemstad J O, Graetz D, et al. 13C-depleted charcoal from C4 grasses and the role of occluded carbon in phytoliths. Org Geochem, 2003, 34: 1337–1352

    Article  Google Scholar 

  35. 35

    Lü H, Wang Y, Wang G, et al. Analysis of carbon isotope in phytoliths from C3 and C4 plants and modern soils. Chinese Sci Bull, 2000, 45: 1804–1808

    Article  Google Scholar 

  36. 36

    Blackman E. Observations on the development of the silica cells of the leaf sheath of wheat (Triticum aestivum). Can J Bot, 1969, 47: 827–838

    Article  Google Scholar 

  37. 37

    Piperno D. Phytolith Analysis: An Archaeological and Geological Perspective. San Diego: Academic Press, 1988. 43–44

    Google Scholar 

  38. 38

    Parr J, Sullivan L, Quirk R. Sugarcane phytoliths: Encapsulation and sequestration of a long-lived carbon fraction. Sugar Tech, 2009, 11: 17–21

    Article  Google Scholar 

  39. 39

    Fang J Y, Guo Z D, Piao S L, et al. Terrestrial vegetation carbon sinks in China, 1981–2000. Sci China Ser D-Earth Sci, 2007, 50: 1341–1350

    Article  Google Scholar 

  40. 40

    Wang Y J, Lu H Y. The Study of Phytolith and Its Application (in Chinese). Beijing: China Ocean Press, 1993. 37–43

    Google Scholar 

  41. 41

    Hodson M J, White P J, Mead A, et al. Phylogenetic variation in the silicon composition of plants. Ann Bot, 2005, 96: 1027–1046

    Article  Google Scholar 

  42. 42

    Parr J, Sullivan L. Phytolith occluded carbon and silica variability in wheat cultivars. Plant Soil, 2011, 342: 165–171

    Article  Google Scholar 

  43. 43

    Kerven G, Menzies N, Geyer M. Soil carbon determination by high temperature combustion: A comparison with dichromate oxidation procedures and the influence of charcoal and carbonate carbon on the measured value. Commun Soil Sci Plant Anal, 2000, 31: 1935–1939

    Article  Google Scholar 

  44. 44

    Chatterjee A, Lal R, Wielopolski L, et al. Evaluation of different soil carbon determination methods. Crit Rev Plant Sci, 2009, 28: 164–178

    Article  Google Scholar 

  45. 45

    Wang Y J. A study on the chemical compostion of phytolths (in Chinese). J Oceano Huanghai Bohai Seas, 1998, 16: 33–38

    Google Scholar 

  46. 46

    Lu H, Zhang J, Liu K-B, et al. Earliest domestication of Common millet (Panicum miliaceum) in East Asia extended to 10000 years ago. Proc Natl Acad Sci USA, 2009, 106: 7367–7372

    Article  Google Scholar 

  47. 47

    Chen W H. Agricultural Archaeology (in Chinese). Beijing: Cultural Press, 2002. 42–48

    Google Scholar 

  48. 48

    You X L. Chinese Agricultural History (in Chinese). Beijing: China Agricultural Press, 2008. 162–173

    Google Scholar 

  49. 49

    Chen X H. The Statistical Data of Chinese Agriculture (in Chinese). Beijing: China Agricultural Press, 2009. 1–236

    Google Scholar 

  50. 50

    Chai Y, Wan F S. A Report for Developing Strategies of Minor Grain Crops in China (in Chinese). Beijing: China Agricultural Science and Technology Press, 2007. 37–53

    Google Scholar 

  51. 51

    Wei Y H. Distribution, production and scientific research survey of bromcorn millet in China. In: Wei Y H, Wang X Y, Chai Y, eds. Chinese Common Millet (in Chinese). Beijing: China Agricultural Press, 1990. 6–11

    Google Scholar 

  52. 52

    Anthoni P, Freibauer A, Kolle O, et al. Winter wheat carbon exchange in Thuringia, Germany. Agriculp Forest Meteorol, 2004, 121: 55–67

    Article  Google Scholar 

  53. 53

    Zhang W J, Wang X J, Xu M G, et al. Soil organic carbon dynamics under long-term fertilizations in arable land of northern China. Biogeosciences, 2010, 7: 409–425

    Article  Google Scholar 

  54. 54

    Zhang F C, Zhu Z H. Harvest index for various crops in China (in Chinese). Sci Agricul Sin, 1990, 23: 83–87

    Google Scholar 

  55. 55

    Wang X Y, Wei Y H. Chinese Contents of Common Millet (in Chinese). Beijing: China Agricultural Press, 1990. 1–302

    Google Scholar 

  56. 56

    National Bureau of Statistics of China. China Statistical Yearbook: 2006 (in Chinese). Beijing: China Statistics Press, 2006

    Google Scholar 

  57. 57

    Gao Z L, Feng X P, Peng K S. Study on the dry land agriculture of north part of China and its sustainable development (in Chinese). Ecol Econ, 2005. 91–94

  58. 58

    Jones L, Milne A, Wadham S. Studies of silica in the oat plant. Plant Soil, 1963, 18: 358–371

    Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to XinXin Zuo.

Additional information

This article is published with open access at

Rights and permissions

This article is published under an open access license. Please check the 'Copyright Information' section either on this page or in the PDF for details of this license and what re-use is permitted. If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and re-use information, please contact the Rights and Permissions team.

About this article

Cite this article

Zuo, X., Lü, H. Carbon sequestration within millet phytoliths from dry-farming of crops in China. Chin. Sci. Bull. 56, 3451–3456 (2011).

Download citation


  • phytoliths
  • carbon sequestration
  • dry-farming
  • phytolith occluded carbon
  • PhytOC