Rhizosphere carbon flow

S. J. Grayston, D. Vaughan, D. Jones. Rhizosphere carbon flow in trees, in comparison with annual plants the importance of root exudation and its impact on microbial activity and nutrient availability. Appl. Soil Ecol. 5 29 (1996). 

A. A. Meharg, A critical review of labelling techniques used to quantify rhizosphere carbon flow. Plant and Soil 166 55 (1994). 

A. A. Meharg and K. Killham, The effect of. soil pH on rhizosphere carbon flow of Lolium perenne. Plant and Soil 123 1 (1990). 

E. Paterson, J. M. Hall, E, A. S. Rattray, B. S. Griffiths, K. Ritz, and K. Killham, Effect of elevated COj on rhizosphere carbon flow and soil microbial processes. Glob. Change Biol. 5 363 (1997). 

Methodological Approaches to the Study of Rhizosphere Carbon Flow and Microbial Population Dynamics... 

Toal, M. E., Yeomans, C., Killham, K. Meharg, A. A. (2000). A review of rhizosphere carbon flow modelling. Plant and Soil, 222, 263-81. 

Killham, K. and C. Yeomans. 2001. Rhizosphere carbon flow measurement and implications from isotopes to reporter genes. Plant Soil 232 (l-2) 91-96. 

Recurrent is the lack of adequate techniques to assess carbon flows through the plants and microbes into soil organic matter (151). Most important is the development of techniques and protocols to separate rhizosphere from nonrhizosphere soil as well as possibly to facilitate analyses of soil carbon dynamics. The use of carbon isotopes, and, where possible, application of double labeling with C and C, seems inevitable in order to separate the contribution of different substrates to the formation of the soil organic matter pool and to get to an understanding of the ecological advantage of exudates and rhizodeposits. 

W. Cheng, D. C. Coleman, C. R. Carroll, and C. A. Hoffman, Investigating shortterm carbon flows in the rhizosphere of different plant species using isotopic trapping. Ai>ron. J. 86 782 (1994). 

Such differences in the amount and type of rhizodeposition that occur on the root with time result in concomitant variations in microbial populations in the rhizosphere, both within the root (endorhizosphere), on the surface of the root (rhizoplane), and in the soil adjacent to the root (ectorhizosphere). The general microbial population changes and specific interaction of individual compounds from specific plants or groups of plants with individual microbial species are covered in detail elsewhere (Chap. 4). Consequently, this chapter is restricted to consideration of methodologies used to study carbon flow and microbial population dynamics in the rhizosphere, drawing on specific plant-microbe examples only when required. 

J. M. Norton, J. L. Smith, and M. K. Firestone, Carbon flow in the rhizosphere of ponderosa pine seedlings. Soil Biol. Biochem. 22 449 (1990). 

Cheng, W., Coleman, D. C., Carroll, C. R., and Hoffman, C. A. (1994). Investigating short-term carbon flows in the rhizospheres of different species, using isotopic trapping. Agron. J. 86, 782-788. 

Rhizosphere modeling remains difficult and complex, as it combines technical know-how from several fields such as plant physiology, soil physics, soil chemistry and mathematics. Mechanistic rhizosphere models do not always operate with adequate precision (Rengel, 1993 Darrah and Roose, 2001). Two main fields of application of mechanistic rhizosphere models are carbon flow in the rhizosphere and nutrient uptake by plants. While carbon flow models study the exudation of carbon compounds into the soil and its consequences on the microbial population, uptake models focus on the transport and uptake of ions by roots. In the following sections, we will concentrate on uptake models on the single root scale. 

Jones, D.L., Nguyen, C., Finlay, R.D. (2009). Carbon Flow in the Rhizosphere Carbon Trading at the Soil-Root Interface. Plant and Soil, Vol. 321, No. 1-2, (August 2009), pp. 5-33, ISSN 1573-5036... 

The rhizosphere is complex and heterogeneous. It contains exudates, lysates, mucilage, secretions, dead cell material and carbon dioxide all of which affect substrate flow to the root (Lynch and Whipps, 1991). Moreover, certain soil micro-... 

---