Soil plant atmosphere continuum

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The Soil-Plant-Atmosphere Continuum (SPAC) is the pathway for water moving from soil through plants to the atmosphere.


The transport of water along this pathway occurs in components, variously defined among scientific disciplines:

SPAC integrates these components and is defined as a:

...concept recognising that the field with all its components (soil, plant, animals and the ambient atmosphere taken together) constitutes a physically integrated, dynamic system in which the various flow processes involving energy and matter occur simultaneously and independently like links in the chain. [1]

This characterises the state of water in different components of the SPAC as expressions of the energy level or water potential of each. Modelling of water transport between components relies on SPAC, as do studies of water potential gradients between segments.

See also[edit]


  1. ^ John R. Philip (1966). Plant water relations: some physical aspects. Annu. Rev. Plant Physiol. 17, 245–268.